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  • Mechanism for generating interstitial atoms by thermal stress during silicon crystal growth
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2019-02-08
    Takao Abe, Toru Takahashi, Koun Shirai

    It has been known that, in growing silicon from melts, vacancies (Vs) predominantly exist in crystals obtained by high-rate growth, while interstitial atoms (Is) predominantly exist in crystals obtained by low-rate growth. To reveal the cause, the temperature distributions in growing crystal surfaces were measured. From this result, it was presumed that the high-rate growth causes a small temperature gradient between the growth interface and the interior of the crystal; in contrast, the low-rate growth causes a large temperature gradient between the growth interface and the interior of the crystal. However, this presumption is opposite to the commonly-accepted notion in melt growth. In order to experimentally demonstrate that the low-rate growth increases the temperature gradient and consequently generates Is, crystals were filled with vacancies by the high-rate growth, and then the pulling was stopped as the extreme condition of the low-rate growth. Nevertheless, the crystals continued to grow spontaneously after the pulling was stopped. Hence, simultaneously with the pulling-stop, the temperature of the melts was increased to melt the spontaneously grown portions, so that the diameters were restored to sizes at the moment of pulling-stop. Then, the crystals were cooled as the cooling time elapsed, and the temperature gradient in the crystals was increased. By using X-ray topographs before and after oxygen precipitation in combination with a minority carrier lifetime distribution, a time-dependent change in the defect type distribution was successfully observed in a three-dimensional manner from the growth interface to the low-temperature portion where the cooling progressed. This result revealed that Vs are uniformly introduced in a grown crystal regardless of the pulling rate as long as the growth continues, and the Vs agglomerate as a void and remain in the crystal, unless recombined with Is. On the other hand, Is are generated only in a region where the temperature gradient is large by low-rate growth. In particular, the generation starts near the peripheral portion in the vicinity of the solid–liquid interface. First, the generated Is are recombined with Vs introduced into the growth interface, so that a recombination region is always formed which is regarded as substantially defect free. Excessively generated Is after the recombination agglomerate and form a dislocation loop region. Unlike conventional Voronkov's diffusion model, Is hardly diffuse over a long distance. Is are generated by re-heating after growth.[In a steady state, the crystal growth rate is synonymous with the pulling rate. Meanwhile, when an atypical operation is performed, the pulling rate is specifically used.]This review on point defects formation intends to contribute further silicon crystals development, because electronic devices are aimed to have finer structures, and there is a demand for more perfect crystals with controlled point defects.

  • FIBSIMS: A review of secondary ion mass spectrometry for analytical dual beam focussed ion beam instruments
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-12-18
    Lex Pillatsch, Fredrik Östlund, Johann Michler

    Secondary ion mass spectrometry (SIMS) is a well-known technique for 3D chemical mapping at the nanoscale, with detection sensitivity in the range of ppm or even ppb. Energy dispersive X-ray spectroscopy (EDS) is the standard chemical analysis and imaging technique in modern scanning electron microscopes (SEM), and related dual-beam focussed ion beam (FIBSEM) instruments. Contrary to the use of an electron beam, in the past the ion beam in FIBSEMs has predominantly been used for local milling or deposition of material. Here, we review the emerging FIBSIMS technique which exploits the focused ion beam as an analytical probe, providing the capability to perform secondary ion mass spectrometry measurements on FIBSEM instruments: secondary ions, sputtered by the FIB, are collected and selected according to their mass by a mass spectrometer. In this way a complete 3D chemical analysis with high lateral resolution < 50 nm and a depth resolution < 10 nm is attainable. We first report on the historical developments of both SIMS and FIB techniques and review recent developments in both instruments. We then review the physics of interaction for incident particles using Monte Carlo simulations. Next, the components of modern FIBSIMS instruments, from the primary ion generation in the liquid metal source in the FIB column, the focussing optics, the sputtered ion extraction optics, to the different mass spectrometer types are all detailed. The advantages and disadvantages of parallel and serial mass selection in terms of data acquisition and interpretation are highlighted, while the effects of pressure in the FIBSEM, acceleration voltage, ion take-off angles and charge compensation techniques on the analysis results are then discussed. The capabilities of FIBSIMS in terms of sensitivity, lateral and depth resolution and mass resolution are reviewed. Different data acquisition strategies related to dwell time, binning and beam control strategies as well as roughness and edge effects are discussed. Data analysis routines for mass identification based on isotope ratios and molecular fragments are outlined. Application examples are then presented for the fields of thin films, polycrystalline metals, batteries, cultural heritage materials, isotope labelling, and geological materials. Finally, FIBSIMS is compared to EDS, and the potential of the technique for correlative microscopy with other FIBSEM based imaging techniques is discussed.

  • Metamorphic InAs(Sb)/InGaAs/InAlAs nanoheterostructures grown on GaAs for efficient mid-IR emitters
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-12-12
    S.V. Ivanov, M.Yu. Chernov, V.A. Solov'ev, P.N. Brunkov, D.D. Firsov, O.S. Komkov

    High-efficiency semiconductor lasers and light-emitting diodes operating in the 3–5 μm mid-infrared (mid-IR) spectral range are currently of great demand for a wide variety of applications, in particular, gas sensing, noninvasive medical tests, IR spectroscopy etc. III-V compounds with a lattice constant of about 6.1 Å are traditionally used for this spectral range. The attractive idea to fabricate such emitters on GaAs substrates by using In(Ga,Al)As compounds is restricted by either the minimum operating wavelength of ∼8 μm in case of pseudomorphic AlGaAs-based quantum cascade lasers or requires utilization of thick metamorphic InxAl1-xAs buffer layers (MBLs) playing a key role in reducing the density of threading dislocations (TDs) in an active region, which otherwise result in a strong decay of the quantum efficiency of such mid-IR emitters. In this review we present the results of careful investigations of employing the convex-graded InxAl1-xAs MBLs for fabrication by molecular beam epitaxy on GaAs (001) substrates of In(Ga,Al)As heterostructures with a combined type-II/type-I InSb/InAs/InGaAs quantum well (QW) for efficient mid-IR emitters (3–3.6 μm). The issues of strain relaxation, elastic stress balance, efficiency of radiative and non-radiative recombination at T = 10–300 K are discussed in relation to molecular beam epitaxy (MBE) growth conditions and designs of the structures. A wide complex of techniques including in-situ reflection high-energy electron diffraction, atomic force microscopy (AFM), scanning and transmission electron microscopies, X-ray diffractometry, reciprocal space mapping, selective area electron diffraction, as well as photoluminescence (PL) and Fourier-transformed infrared spectroscopy was used to study in detail structural and optical properties of the metamorphic QW structures. Optimization of the growth conditions (the substrate temperature, the As4/III ratio) and elastic strain profiles governed by variation of an inverse step in the In content profile between the MBL and the InAlAs virtual substrate results in decrease in the TD density (down to 3 × 107 cm−2), increase of the thickness of the low-TD-density near-surface MBL region to 250–300 nm, the extremely low surface roughness with the RMS value of 1.6–2.4 nm, measured by AFM, as well as rather high 3.5 μm-PL intensity at temperatures up to 300 K in such structures. The obtained results indicate that the metamorphic InSb/In(Ga,Al)As QW heterostructures of proper design, grown under the optimum MBE conditions, are very promising for fabricating the efficient mid-IR emitters on a GaAs platform.

  • Sapphire shaped crystals for waveguiding, sensing and exposure applications
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-11-28
    G.M. Katyba, K.I. Zaytsev, I.N. Dolganova, I.A. Shikunova, N.V. Chernomyrdin, S.O. Yurchenko, G.A. Komandin, I.V. Reshetov, V.V. Nesvizhevsky, V.N. Kurlov

    Second half of the XX century was marked by a rapid development of sapphire shaped crystal growth technologies, driven by the demands for fast, low-cost, and technologically reliable methods of producing sapphire crystals of complex shape. Numerous techniques of shaped crystal growth from a melt have been proposed relying on the Stepanov concept of crystal shaping. In this review, we briefly describe the development of growth techniques, with a strong emphasize on those that yield sapphire crystals featuring high volumetric and surface quality. A favorable combination of physical properties of sapphire (superior hardness and tensile strength, impressive thermal conductivity and chemical inertness, high melting point and thermal shock resistance, transparency to electromagnetic waves in a wide spectral range) with advantages of shaped crystal growth techniques (primarily, an ability to produce sapphire crystals with a complex geometry of cross-section, along with high volumetric and surface quality) allows fabricating various instruments for waveguiding, sensing, and exposure technologies. We discuss recent developments of high-tech instruments, which are based on sapphire shaped crystals and vigorously employed in biomedical and material sciences, optics and photonics, nuclear physics and plasma sciences.

  • Surface modification and grafting of carbon fibers: A route to better interface
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-07-25
    Nischith Raphael, K. Namratha, B.N. Chandrashekar, Kishor Kumar Sadasivuni, Deepalekshmi Ponnamma, A.S. Smitha, S. Krishnaveni, Chun Cheng, K. Byrappa

    This review is an audit of various Carbon fibers (CF) surface modification techniques that have been attempted and which produced results with an enhancement in the interfacial characteristics of CFRP systems. An introduction to the CF surface morphology, various techniques of modifications, their results and challenges are discussed here. CFs are emerging as the most promising materials for designing many technologically significant materials for current and future generations. In order to extract all the physic-mechanical properties of CF, it is essential to modulate a suitable environment through which good interfacial relation is achieved between the CF and the matrix. The interface has the utmost significance in composites and hybrid materials since tension at the interface can result in a deterioration of the fundamental properties. This review is aimed to provide a detailed understanding of the CF structure, its possible ways of modification, and the influence of interfacial compatibility in physic-mechanical and tribological properties. Both physical and chemical modifications are illustrated with specific examples, in addition to the characterization methods. Overall, this article provides key information about the CF based composite fabrication and their many applications in aerospace and electronics- where light weight and excellent mechanical strength are required.

  • Basic ammonothermal growth of Gallium Nitride – State of the art, challenges, perspectives
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-06-02
    M. Zajac, R. Kucharski, K. Grabianska, A. Gwardys-Bak, A. Puchalski, D. Wasik, E. Litwin-Staszewska, R. Piotrzkowski, J. Z Domagala, M. Bockowski

    Recent progress in ammonothermal technology of bulk GaN growth in basic environment is presented and discussed in this paper. This method enables growth of two-inch in diameter crystals of outstanding structural properties, with radius of curvature above tens of meters and low threading dislocation density of the order of 5 × 104 cm−2. Crystals with different types of conductivity, n-type with free electron concentration up to 1019 cm−3, p-type with free hole concentration of 1016 cm−3, and semi-insulating with resistivity exceeding 1011 Ω cm, can be obtained. Ammonothermal GaN of various electrical properties is described in terms of point defects present in the material. Potential applications of high-quality GaN substrates are also briefly shown.

  • Solution combustion synthesis, energy and environment: Best parameters for better materials
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-05-18
    Francesca Deganello, Avesh Kumar Tyagi

    Solution combustion synthesis (SCS) is a worldwide used methodology for the preparation of inorganic ceramic and composite materials with controlled properties for a wide number of applications, from catalysis to photocatalysis and electrocatalysis, from heavy metal removal to sensoristics and electronics. The high versatility and efficiency of this technique have led to the introduction of many variants, which allowed important optimization to the prepared materials. Moreover, its ecofriendly nature encouraged further studies about the use of sustainable precursors for the preparation of nanomaterials for energy and environment, according to the concept of circular economy. On the other hand, the large variety of expressions to define SCS and the often-contradictory definitions of the SCS parameters witnessed a scarce consciousness of the potentiality of this methodology. In this review article, the most important findings about SCS and the selection criteria for its main parameters are critically reviewed, in order to give useful guidelines to those scientists who want to use this methodology for preparing materials with improved or new functional properties. This review aims as well (i) to bring more clarity in the SCS terminology (ii) to increase the awareness of the SCS as a convenient tool for the synthesis of materials and (iii) to propose a new perspective in the SCS, with special attention to the use of ecofriendly procedures. Part of the review is also dedicated to precautions and limitations of this powerful methodology.

  • Metalorganic vapor phase epitaxy of III–V-on-silicon: Experiment and theory
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2018-11-13
    Oliver Supplie, Oleksandr Romanyuk, Christian Koppka, Matthias Steidl, Andreas Nägelein, Agnieszka Paszuk, Lars Winterfeld, Anja Dobrich, Peter Kleinschmidt, Erich Runge, Thomas Hannappel

    The integration of III–V semiconductors with Si has been pursued for more than 25 years since it is strongly desired in various high-efficiency applications ranging from microelectronics to energy conversion. In the last decade, there have been tremendous advances in Si preparation in hydrogen-based metalorganic vapor phase epitaxy (MOVPE) environment, III–V nucleation and subsequent heteroepitaxial layer growth. Simultaneously, MOVPE itself took off in its triumphal course in solid state lighting production demonstrating its power as industrially relevant growth technique. Here, we review the recent progress in MOVPE growth of III–V-on-silicon heterostructures, preparation of the involved interfaces and fabrication of devices structures. We focus on a broad range of in situ, in system and ex situ characterization techniques. We highlight important contributions of density functional theory and kinetic growth simulations to a deeper understanding of growth phenomena and support of the experimental analysis. Besides new device concepts for planar heterostructures and the specific challenges of (001) interfaces, we also cover nano-dimensioned III–V structures, which are preferentially prepared on (111) surfaces and which emerged as veritable candidates for future optoelectronic devices.

  • 更新日期:2018-07-12
  • Epitaxial growth of highly mismatched III-V materials on (001) silicon for electronics and optoelectronics
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2017-11-14
    Qiang Li, Kei May Lau

    Monolithic integration of III-V on silicon has been a scientifically appealing concept for decades. Notable progress has recently been made in this research area, fueled by significant interests of the electronics industry in high-mobility channel transistors and the booming development of silicon photonics technology. In this review article, we outline the fundamental roadblocks for the epitaxial growth of highly mismatched III-V materials, including arsenides, phosphides, and antimonides, on (001) oriented silicon substrates. Advances in hetero-epitaxy and selective-area hetero-epitaxy from micro to nano length scales are discussed. Opportunities in emerging electronics and integrated photonics are also presented.

  • 更新日期:2018-06-03
  • 更新日期:2018-06-03
  • Germanium based photonic components toward a full silicon/germanium photonic platform
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2017-05-20
    V. Reboud, A. Gassenq, J.M. Hartmann, J. Widiez, L. Virot, J. Aubin, K. Guilloy, S. Tardif, J.M. Fédéli, N. Pauc, A. Chelnokov, V. Calvo

    Lately, germanium based materials attract a lot of interest as they can overcome some limits inherent to standard Silicon Photonics devices and can be used notably in Mid-Infra-Red sensing applications. The quality of epitaxially grown intrinsic and doped materials is critical to reach the targeted performances. One of the main challenges in the field remains the fabrication of efficient group-IV laser sources compatible with the microelectronics industry, seen as an alternative to the complexity of integration of III-V lasers on Si. The difficulties come from the fact that the group-IV semiconductor bandgap has to be transformed from indirect to direct, using high tensile strains or by alloying germanium with tin. Here, we review recent progresses on critical germanium-based photonic components such as waveguides, photodiodes and modulators and discuss the latest advances towards germanium-based lasers. We show that novel optical germanium-On-Insulator (GeOI) substrates fabricated by the Smart Cut™ technology is a key feature for future Si - Complementary Metal Oxide Semiconductor (CMOS) - compatible laser demonstration. This review hints at a future photonics platform based on germanium and Silicon.

  • Molecular beam epitaxy as a growth technique for achieving free-standing zinc-blende GaN and wurtzite AlxGa1-xN
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2017-04-25
    S.V. Novikov, A.J. Kent, C.T. Foxon

    Currently there is a high level of interest in the development of ultraviolet (UV) light sources for solid-state lighting, optical sensors, surface decontamination and water purification. III-V semiconductor UV LEDs are now successfully manufactured using the AlGaN material system; however, their efficiency is still low. The majority of UV LEDs require AlxGa1-xN layers with compositions in the mid-range between AlN and GaN. Because there is a significant difference in the lattice parameters of GaN and AlN, AlxGa1-xN substrates would be preferable to those of either GaN or AlN for many ultraviolet device applications. However, the growth of AlxGa1-xN bulk crystals by any standard bulk growth techniques has not been developed so far. There are very strong electric polarization fields inside the wurtzite (hexagonal) group III-nitride structures. The charge separation within quantum wells leads to a significant reduction in the efficiency of optoelectronic device structures. Therefore, the growth of non-polar and semi-polar group III-nitride structures has been the subject of considerable interest recently. A direct way to eliminate polarization effects is to use non-polar (001) zinc-blende (cubic) III-nitride layers. However, attempts to grow zinc-blende GaN bulk crystals by any standard bulk growth techniques were not successful. Molecular beam epitaxy (MBE) is normally regarded as an epitaxial technique for the growth of very thin layers with monolayer control of their thickness. In this study we have used plasma-assisted molecular beam epitaxy (PA-MBE) and have produced for the first time free-standing layers of zinc-blende GaN up to 100 μm in thickness and up to 3-inch in diameter. We have shown that our newly developed PA-MBE process for the growth of zinc-blende GaN layers can also be used to achieve free-standing wurtzite AlxGa1-xN wafers. Zinc-blende and wurtzite AlxGa1-xN polytypes can be grown on different orientations of GaAs substrates - (001) and (111)B respectively. We have subsequently removed the GaAs using a chemical etch in order to produce free-standing GaN and AlxGa1-xN wafers. At a thickness of ∼30 µm, free-standing GaN and AlxGa1-xN wafers can easily be handled without cracking. Therefore, free-standing GaN and AlxGa1-xN wafers with thicknesses in the 30–100 μm range may be used as substrates for further growth of GaN and AlxGa1-xN-based structures and devices. We have compared different RF nitrogen plasma sources for the growth of thick nitride AlxGa1-xN films including a standard HD25 source from Oxford Applied Research and a novel high efficiency source from Riber. We have investigated a wide range of the growth rates from 0.2 to 3 µm/h. The use of highly efficient nitrogen RF plasma sources makes PA-MBE a potentially viable commercial process, since free-standing films can be achieved in a single day. Our results have demonstrated that MBE may be competitive with the other group III-nitrides bulk growth techniques in several important areas including production of free-standing zinc-blende (cubic) (Al)GaN and of free-standing wurtzite (hexagonal) AlGaN.

  • 更新日期:2018-06-03
  • Spray pyrolysis deposition of undoped SnO2 and In2O3 films and their structural properties
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2017-01-12
    G. Korotcenkov, B.K. Cho

    In this paper the results of structural analysis of the SnO2 and In2O3 films deposited by spray pyrolysis are presented. The main goals of this analysis are summarizing the results obtained in this field, highlighting a correlation between parameters of film deposition and the material structure and formulating some general regularities, typical for metal oxides. Peculiarities and mechanisms of pyrosol deposition as well as advantages and disadvantages of this technology for deposition of the films with required parameters were also discussed. It is shown that this technology has great potential for controlling structural parameters of metal oxides such as thickness, the grain size, texturing, roughness, the grain faceting and the porosity.

  • Atomic layer deposition of high-k dielectrics on III–V semiconductor surfaces
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-12-02
    Theodosia Gougousi

    The goal of this article is to provide an overview of the state of knowledge regarding the Atomic Layer Deposition (ALD) of metal oxides on III–V semiconductor surfaces. An introduction to ALD, the band structure, various defects present on the III–V surface and how they relate to Fermi level pinning are discussed. Surface passivation approaches are examined in detail in conjunction with experimental and computational results. The “interface clean-up” reaction that leads to the formation of a sharp gate oxide/semiconductor interface is related to the surface chemistry and the transport of the surface oxides through the growing dielectric film. Finally, the deposition of metal oxides on semiconductors is discussed in the context of interface quality and some examples of devices using III–V channels and ALD metal oxides are given.

  • Single crystal growth by the traveling solvent technique: A review
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-05-06
    S.M. Koohpayeh

    A description is given of the traveling solvent technique, which has been used for the crystal growth of both congruently and incongruently melting materials of many classes of intermetallic, chalcogenide, semiconductor and oxide materials. The use of a solvent, growth at lower temperatures and the zoning process, that are inherent ingredients of the method, can help to grow large, high structural quality, high purity crystals. In order to optimize this process, careful control of the various growth variables is imperative; however, this can be difficult to achieve due to the large number of independent experimental parameters that can be grouped under the broad headings ‘growth conditions’, ‘characteristics of the material being grown’, and ‘experimental configuration, setup and design’. This review attempts to describe the principles behind the traveling solvent technique and the various experimental variables. Guidelines are detailed to provide the information necessary to allow closer control of the crystal growth process through a systematic approach. Comparison is made between the traveling solvent technique and other crystal growth methods, in particular the more conventional stationary flux method. The use of optical heating is described in detail and successful traveling solvent growth by optical heating is reported for the first time for crystals of Tl5Te3, Cd3As2, and FeSc2S4 (using Te, Cd and FeS fluxes, respectively).

  • Spring and parachute: How cocrystals enhance solubility
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-08-04
    Dhara D. Bavishi, Chetan H. Borkhataria

    This article is intended to combine literature on cocrystallization – a tool for enhancing the solubility and for improving the physicochemical properties of an API (an API is the molecule which is responsible for providing the therapeutic effect) with special emphasis on the mechanism responsible for the same. The pharmaceutical industries are witnessing a developing crisis in the process of drug development due to the increasing cost of their R&D departments, the failure of some blockbuster drug candidates exhibiting poor aqueous solubility and the unavailability of newer molecules because of patent limitations. Cocrystallization is an emerging approach to improve solubility, dissolution profile, bioavailability, and other physicochemical and mechanical properties of an API. A pharmaceutical cocrystal is now a new epitome which enables the use of a wide range of active pharmaceutical ingredients without the need to form or break the covalent bonds. The prime focus of this review article is the mechanism on how cocrystals have a solubility advantage over the amorphous form. This review also provides a brief introduction to the nature of cocrystals, their role, principles of crystal engineering and also highlights the nature of supramolecular synthons which are present in cocrystals.

  • Recent progress in chemical vapor deposition growth of two-dimensional transition metal dichalcogenides
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-07-28
    Swee Liang Wong, Hongfei Liu, Dongzhi Chi

    Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have received significant attention recently due to their unique properties such as a transition from indirect to direct band gap when thinned down to a monolayer and also valley-dependent photoluminescence. In addition, being a semiconductor with considerable mobility, it has been touted as a candidate in next generation electronics. However, a major hurdle to its implementation is the difficulty in producing large areas of these 2D TMDCs with well-defined thicknesses. In this review, we will first introduce the basic properties as well as the various synthesis methods of 2D TMDCs. Focus will be placed on recent advances in chemical vapor deposition (CVD) growth as they currently yield the largest areas. Obstacles present in CVD growth will be presented and existing solutions to them will be discussed in tandem with current characterization methods for evaluation of crystal quality. Through our presentation on the latest approaches to issues in CVD growth, we hope to present the readers a perspective on recent developments as well as providing an outlook on the future of CVD growth of TMDCs.

  • Crystallization behavior of solid solutions from aqueous solutions: An environmental perspective
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-07-01
    Manuel Prieto, Frank Heberling, Rosa M. Rodríguez-Galán, Felix Brandt

    Aqueous–solid solution (AQ-SS) processes have garnered increasing attention from geochemists and environmental engineers because they play major roles in the fate and transport of elements in Earth surface environments. The reasons for this interest include: (i) the primary crystallization of minerals from multicomponent aqueous solutions leads to the formation of solid solutions in which different ions are substituted for one another in equivalent structural positions; (ii) the interaction between pre-existing minerals and water frequently yields surface precipitation and dissolution–recrystallization processes in which such substituting ions redistribute to adapt to new physicochemical conditions; (iii) the concentrations of specific minor elements in biogenic and abiogenic minerals have been shown to correlate with various parameters characterizing the growth environment (temperature, pH, nutrient levels, salinity, etc.) and the corresponding compositional signatures can be powerful tools in reconstructing the past from the sedimentary record; (iv) the aqueous concentration of heavy metals and other harmful ions can be significantly reduced by their incorporation into the structure of suitable host minerals and as such a ‘reduction of solubility’ can be exploited as a remediation strategy or used to design engineered barriers for the retention of metals, radionuclides, and other industrially generated inorganic wastes. In this review, the thermodynamics driving of AQ-SS processes is presented using examples of environmentally-relevant systems. The reaction pathways in AQ-SS processes depend not only on thermodynamic factors but also on kinetic and mechanistic effects, which operate at different scales in space and time. Examples of such effects include non-equilibrium ion partitioning, surface passivation, and compositional (sectorial, concentric, oscillatory) zoning. Finally, we discuss the contribution of both state-of-the-art characterization techniques and molecular simulation methods for the development of predictive models.

  • Thermodynamics -for understanding crystal growth-
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-07
    Tatau Nishinaga

    To understand what entropy is, thermodynamical entropy was derived from Boltzmann's entropy formula. After defining the Helmholtz and the Gibbs free energies, we calculated the formation Gibbs free energies of an equilibrium and a non-equilibrium nucleus following Toschev's approach taking a water droplet as an example. It is demonstrated that the Gibbs free energy for the formation of a cluster takes the maximum as the cluster radius is increased. The cluster at this maximum is called critical nucleus. Thermodynamics is also a useful tool to obtain the rate of crystal growth in a vapor phase. The partial pressures of all gaseous species are calculated by solving equations given by the law of mass action and the initial conditions. The mathematical formulas to give the growth rates in a closed tube and in a gas flow system are derived.

  • Introduction to the BCF theory
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-01
    Makio Uwaha

    Sixty-five years have passed since Burton, Cabrera and Frank (BCF) published the seminal paper (W. K. Burton, N. Cabrera and F. C. Frank, Phil. Trans. Royal Soc. London, 243 (1951), 299). Since then, the paper provided us the basic scheme of growth of crystals. In this lecture, the BCF theory is introduced for beginners as the basis of modern crystal growth study. The BCF theory explained the growth of facets with the help of screw dislocations. It introduced the concept of the roughening transition, which distinguishes the crucial difference of lateral growth of facets and normal growth of round surfaces.

  • In-situ liquid phase TEM observations of nucleation and growth processes
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-20
    James J. De Yoreo

    Nucleation and growth of crystals is a pervasive phenomenon in the synthesis of man-made materials, as well as mineral formation within geochemical and biological environments. Over the past two decades, numerous ex situ studies of crystallization have concluded that nucleation and growth pathways are more complex than envisioned within classical models. The recent development of in situ liquid phase TEM (LP-TEM) has led to new insights into such pathways by enabling direct, real-time observations of nucleation and growth events. Here we report results from LP-TEM studies of Au nanoparticle, CaCO3 and iron oxide formation. We show how these in situ data can be used to obtain direct evidence for the mechanisms underlying crystallization, as well as dynamic information that provides constraints on important kinetic and thermodynamic parameters not available through ex situ methods.

  • Fundamentals and engineering of defects
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-01
    Peter Rudolph

    An overview of the important defect types, their origins and interactions during the bulk crystal growth from the melt and selected epitaxial processes is given. The equilibrium and nonequilibrium thermodynamics, kinetics and interaction principles are considered as driving forces of defect generation, incorporation and assembling. Results of modeling and practical in situ control are presented. Strong emphasis is given to semiconductor crystal growth since it is from this class of materials that most has been first learned, the resulting knowledge then having been applied to other classes of material. The treatment starts with melt-structure considerations and zero-dimensional defect types, i.e. native and extrinsic point defects. Their generation and incorporation mechanisms are discussed. Micro- and macro-segregation phenomena – striations and the effect of constitutional supercooling – are added. Dislocations and their patterning are discussed next. The role of high-temperature dislocation dynamics for collective interactions, like cell structuring and bunching, is specified. Additionally, some features of epitaxial dislocation kinetics and engineering are illustrated. Next the grain boundary formation mechanisms, such as dynamic polygonization and interface instabilities, are discussed. The interplay between facets, inhomogeneous dopant incorporations and twinning is shown. Finally, second phase precipitation and inclusion trapping are discussed. The importance of in situ stoichiometry control is underlined. Generally, selected measures of defect engineering are given at the end of each sub-chapter.

  • In-situ observation of crystal growth and the mechanism
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-17
    Katsuo Tsukamoto

    The spatial and time resolution in the measurements of growth rates and the observation of surface morphologies and the associated transport phenomena reflecting their growth mechanism have been developed because advanced microscopes and interferometers have attained nano-scale resolution. The first part covers the historical background how in-situ observation of crystal growth at molecular-level by optical and other scanning methods had been developed for understanding of crystal growth by measuring crystal growth rates and by observing surface nano-topographies, such as growth steps and spiral hillocks, with the same vertical resolutions comparable to that of the scanning probe microscopic techniques. The potential of recently developed interferometric techniques, such as Phase-Shift Interferometry (PSI) is then reviewed with the principle of the optics. Capability of measuring growth rates of crystals as low as 10−5 nm/s (1 µm/year) is introduced. Second part of the article emphasizes basic interferometric technique for the understanding of crystal growth mechanism by measuring growth rate vs supersaturation. Utilization of these techniques not only in fundamental crystal growth fields but also in environmental sciences, space sciences and crystallization in microgravity would briefly be introduced. At the end, we select a few examples how growth mechanism was analyzed based on these kinetic measurements.

  • Development of GaN-based blue LEDs and metalorganic vapor phase epitaxy of GaN and related materials
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Hiroshi Amano

    This article combines two papers, “Nobel Lecture: Growth of GaN on sapphire via low-temperature deposited buffer layer and realization of p-type GaN by Mg doping followed by low-energy electron beam irradiation,” Rev. Mod. Phys., 87 (2015) 1133, and “MOCVD of nitrides,” Handbook of Crystal Growth Second Edition, Volume III, Part A, Chapter 16, Elsevier, 683–704, 2015. For more detailed information, please read the two original papers.

  • Nucleation of protein crystals
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Peter G. Vekilov

    Protein crystal nucleation is a central problem in biological crystallography and other areas of science, technology, and medicine. Recent studies have demonstrated that protein crystal nuclei form within crucial precursors. Data for several proteins provided by these methods have demonstrated that the nucleation precursors are clusters consisting of protein dense liquid, which are metastable with respect to the host protein solution. The clusters are several hundred nanometers in size, they occupy from 10−7 to 10−3 of the solution volume, and their properties in solutions supersaturated with respect to crystals are similar to those in homogeneous, i.e., undersaturated, solutions. The clusters exist due to the conformation flexibility of the protein molecules, leading to the exposure of hydrophobic surfaces and enhanced intermolecular binding. These results indicate that protein conformational flexibility might be the mechanism behind the metastable mesoscopic clusters and crystal nucleation. The investigations of the cluster properties are still in their infancy. Results on direct imaging of cluster behaviors and characterization of cluster mechanisms with a variety of proteins will soon lead to major breakthroughs in protein biophysics.

  • Growth and low-energy electron microscopy characterizations of graphene and hexagonal boron nitride
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-01
    H. Hibino, S. Wang, C.M. Orofeo, H. Kageshima

    Graphene and related two-dimensional (2D) materials are attracting huge attention due to their wide-range potential applications. Because large-scale, high-quality 2D crystals are prerequisites for many of the applications, crystal growth of 2D materials has been intensively studied. We have also been conducting research to understand the growth mechanism of 2D materials and have been developing growth techniques of high-quality materials based on the understandings, in which detailed structural characterizations using low-energy electron microscopy (LEEM) have played essential roles. In this paper, we explain the principles of obtaining various structural features using LEEM, and then we review the status of our current understanding on the growth of graphene and hexagonal boron nitride.

  • Solid-state wetting at the nanoscale
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Olivier Pierre-Louis

    The aim of this lecture is to provide an overview on solid-state wetting, starting from basic concepts, and introducing the useful mathematical paraphernalia. We review and discuss the similarities and the differences between liquid-state and solid-state wetting. Then, we show how wetting concepts provide tools to understand the morphology and stability of solid-state thin films and nano-islands.

  • The role of surface and interface structure in crystal growth
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-03
    Elias Vlieg

    Crystal growth occurs at the interface of a crystal and its growth medium. Due to the abrupt termination at the surface, at the interface the properties of the crystal will typically deviate from the bulk and this can affect the growth behaviour. Also the properties of the growth medium at the interface will typically differ from the bulk. In growth from solution, for example, the liquid will show ordering induced by the crystal surface or have a different composition. Here techniques to study such growth interfaces will be discussed together with examples of the effect that the properties of the interface can have on the growth.

  • Mesostructured crystals: Growth processes and features
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-20
    Hiroaki Imai

    Sophisticated architectures consisting of oriented small crystalline blocks are widely observed in biological and biomimetic minerals. Here, mesostructured crystals are categorized in a new family of crystalline states as intermediate between faceted single crystals and polycrystals that are random arrangements of small grains. A variety of hierarchical architectures, such as mesocrystals consisting of isolated nanoblocks, granular textures of biominerals, and helical crystals, are included in the mesostructured crystals. The formation routes of the mesostructured crystals are described on the basis of the specific interaction of crystals and organic molecules or matrices. Moreover, specific features of the particular crystalline states are shown with their unique functions originating from the hierarchical architectures.

  • Three study cases of growth morphology in minerals: Halite, calcite and gypsum
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-05-30
    Dino Aquilano, Fermín Otálora, Linda Pastero, Juan Manuel García-Ruiz

    Beyond fundamental aspects of crystal growth and morphology, the growth of minerals is a challenging subject because in most cases we face a problem with unknown growth conditions. Actually, in the field of geological studies, we have to decipher the growth conditions of a crystal using the information contained in the very crystal. One of these characteristics of crystals that contain information about their growth is their morphology and time evolution. In this article, we introduce the subject of crystal morphology by using three important minerals, calcite, halite and gypsum, as three didactic case studies to illustrate the application of the current knowledge in the field.

  • Selective nucleation and self-organized crystallization
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-29
    Fei Jia, Di Zhao, Mu Wang

    Nucleation is an important step in crystallization, and many self-organized patterns are determined in this process. In this study, after briefly reviewing the fundamentals of nucleation theory, we take a few examples to show the significance of concave-corner-mediated nucleation in both self-organized formation of long-range-ordered patterns and in self-assembly of metallic nano wire array. We show that successive concave-corner-mediated nucleation on the growth front is an important mechanism leading to many long-range ordering effects in crystallization. This mechanism can also be applied in fabricating metallic nano wires with specific geometry, including straight metallic wire array with tunable line width and nanowires with periodic structures.

  • Growth of semiconductor silicon crystals
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-05-30
    Koichi Kakimoto, Bing Gao, Xin Liu, Satoshi Nakano

    This paper focuses on the recent developments in Czochralski (CZ) crystal growth of silicon for large-scale integrated circuits (LSIs) and multi-crystalline silicon growth using a directional solidification method for solar cells. Growth of silicon crystals by the CZ method currently allows the growth of high-quality crystals that satisfy the device requirements of LSIs or power devices for electric cars. This paper covers how to obtain high-quality crystals with low impurity content and few point defects. It also covers the directional solidification method, which yields crystals with medium conversion efficiency for photovoltaic applications. We discuss the defects and impurities that degrade the efficiency and the steps to overcome these problems.

  • Fluid dynamics in crystal growth: The good, the bad, and the ugly
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-05-27
    Jeffrey J. Derby

    Fluid dynamics are important in processes that grow large crystals from a liquid phase. This paper presents a primer on fluid mechanics and convection, followed by a discussion of the physics and scaling of flows in such processes. Specific examples of fluid flows in crystal growth systems are presented and classified according to their impact on outcomes, good or bad. Turbulence in crystal growth is discussed within the limited extent of our understanding, which is incomplete, or ugly.

  • Microchannel epitaxy
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-11
    Shigeya Naritsuka

    Microchannel epitaxy (MCE) is an outstanding technique for dislocation reduction during heteroepitaxial growth when there is a large lattice mismatch. This paper describes the MCE mechanism in detail together with experimental results. Directional growth is a principal concern of MCE, and is enabled through the assessment and control of the elementary processes of crystal growth. Vertical microchannel epitaxy (V-MCE) involves perpendicular growth relative to a substrate, from microchannels established as openings in a mask, while horizontal microchannel epitaxy (H-MCE) is growth parallel to the substrate surface. Even if many dislocations are present in the microchannels, directional growth vastly reduces their number in the grown crystal. MCE is beneficial for the fabrication of devices, as well as the quantitative study of the fundamental processes involved in crystal growth. This paper quantitatively discusses the growth mechanism involved in H-MCE of GaAs in the thickness direction. Fitting the forms of spiral steps observed on flat surfaces at an atomic level enables the accurate derivation of surface supersaturation at the time of growth. Moreover, since a simple mechanism for controlling growth in the vertical direction can be established for H-MCE with a single step source, quantitative discussion of crystal-growth mechanisms is now possible.

  • Diamond epitaxy: Basics and applications
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Makoto Kasu

    Diamond has been used as cutting tools, and also has recently attracted extensive attention as a semiconductor. In the review, its properties and prospects of its electronic devices are shown. Then, principles of crystal growth methods, such as high-pressure, high-temperature (HPHT) and chemical vapor deposition (CVD) methods, are described. Next, current understanding of defects such as dislocations and stacking faults is described. Further, for the future electronic applications, the present status of wafer technology and impurity doping are described. Finally, the electronic devices made of diamond semiconductors are shown.

  • Bulk and epitaxial growth of silicon carbide
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-05-27
    Tsunenobu Kimoto

    Silicon carbide (SiC) is a wide bandgap semiconductor having high critical electric field strength, making it especially attractive for high-power and high-temperature devices. Recent development of SiC devices relies on rapid progress in bulk and epitaxial growth technology of high-quality SiC crystals. At present, the standard technique for SiC bulk growth is the seeded sublimation method. In spite of difficulties in the growth at very high temperature above 2300 °C, 150-mm-diameter SiC wafers are currently produced. Through extensive growth simulation studies and minimizing thermal stress during sublimation growth, the dislocation density of SiC wafers has been reduced to 3000–5000 cm−2 or lower. Homoepitaxial growth of SiC by chemical vapor deposition has shown remarkable progress, with polytype replication and wide range control of doping densities (1014–1019 cm−3) in both n- and p-type materials, which was achieved using step-flow growth and controlling the C/Si ratio, respectively. Types and structures of major extended and point defects in SiC epitaxial layers have been investigated, and basic phenomena of defect generation and reduction during SiC epitaxy have been clarified. In this paper, the fundamental aspects and technological developments involved in SiC bulk and homoepitaxial growth are reviewed.

  • III-V compound semiconductors: Growth and structures
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-06
    Thomas F. Kuech

    The semiconductors formed from group 13 metals and from group 15 anions, referred to as the III-V semiconductors, have found use in a broad range of technologies. Their versatility arises from the wide range of optical and electronic properties accessed through the formation of multi-component alloys. These alloys can be synthesized using the epitaxial growth techniques for devices consisting of several-to-hundreds of highly controlled individual layers monolithically formed into a nearly defect-free structure. This ability to design and fabricate such detailed structures, whose dimensions can be at the nanometer scale, has been driven by an understanding of the crystal growth and materials technology. The paper introduces key features of these materials, their materials science and crystal growth.

  • Heusler compounds and spintronics
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-30
    Chris J. Palmstrøm

    Heusler compounds are a large group of intermetallic compounds with over 1000 members with similar crystal structures having a vast array of tunable properties. These properties depend on the number of valence electrons per formula unit allowing tuning of properties through composition and alloying. The Heusler lattice parameters span many metal oxides and semiconductors and their crystal structures are closely related. For spintronic applications, the magnetic and half-metallic properties, in particular, are of great interest. In this paper the electronic and magnetic properties of Heusler compounds are discussed as well as the importance of composition and defect control on tailoring their properties. Examples of applications include the great success of Heusler magnetic tunnel junction in metallic spintronic devices. The potential of going beyond metallic spintronics to the integration of Heusler compounds with III–V semiconductors for semiconductor spintronics device physics and technology, the tuning of magnetic properties, and the fabrication of Heusler compound heterostructures and superlattices are also discussed.

  • Polymorphism of edible fat crystals
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Hironori Hondoh, Satoru Ueno

    The course focuses on the polymorphism and polymorphic transformation of edible fat crystals, such as chocolate. The morphology, crystallization behavior and polymorphic transformation will be observed under optical microscopy, and melting point of each polymorph will be determined.

  • Assembling interferometers and in-situ observation of ambient environments and solid–liquid interfaces
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Yuki Kimura, Kenta Murayama, Tomoya Yamazaki, Takao Maki

    The principle of interferometers and its applicability to our research on crystal growth can be understood through assembling interferometers. In particular, practical skills such as techniques for assembling interferometers and selecting optical components, which are not covered by general textbooks, can be learned.

  • Observing crystal growth processes in computer simulations
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-03
    Hiroki Nada, Hitoshi Miura, Jun Kawano, Toshiharu Irisawa

    This paper presents the outline of a practical course on computer simulation that will be given at the 16th International Summer School on Crystal Growth (ISSCG-16). The aim of this course is to understand crystal growth processes from the molecular level to the macroscopic level through computer simulations. We will mainly study molecular-scale crystal growth and nucleation processes by using molecular dynamics simulations and macroscopic growth processes at crystal surfaces by using phase field simulations.

  • In-situ observation of crystal surfaces by optical microscopy
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-03
    Gen Sazaki, Ken Nagashima, Ken-ichiro Murata, Yoshinori Furukawa

    In this experimental course, attendees will learn how to obtain useful information about growth processes of crystals using ordinary optical microscopes, which are usually available in laboratories. We will demonstrate how thicknesses of crystals can be estimated from interference colors. We will also show in-situ observations of spiral steps and strain distributions by differential interference contrast microscopy and polarizing microscopy, respectively.

  • In-situ observation of colloidal crystallization
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-06-02
    Junpei Yamanaka, Yoshihisa Suzuki, Jun Nozawa, Tsutomu Sawada
  • Si–Ge–Sn alloys: From growth to applications
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2016-01-18
    S. Wirths, D. Buca, S. Mantl
  • Modern chemical synthesis methods towards low-dimensional phase change structures in the Ge–Sb–Te material system
    Prog. Cryst. Growth Ch. Mater. (IF 3.147) Pub Date : 2015-11-14
    Hilde Hardtdegen, Martin Mikulics, Sally Rieß, Martin Schuck, Tobias Saltzmann, Ulrich Simon, Massimo Longo

    This report centers on different modern chemical synthesis methods suitable for production with which low-dimensional crystalline structures are attainable in the Ge–Sb–Te material system. The general characteristics of the methods are described first. The special challenges are discussed for the Ge–Sb–Te material system. Growth optimization is studied, and the resulting nanostructures are presented. At last a comparison of the methods is given with respect to research scale vapor transport approach on the one hand and the potential described for future application in technology on the other hand.

Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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