Atomic layer etching (ALE) is a multistep process used for removing ultrathin layers of the material. The removal step can be driven by ion bombardment, typically with energies of <100 eV and step times of >1 s. Previously, we reported a new ALE operating regime where exposures to ion energies were >500 eV and step times were <1 s. This paper provides a simple theoretical basis for unifying the low

In this special issue honoring Professor Arthur Gossard, I am delighted to be able to review a small segment of the work he has enabled while at UCSB on the subject of the title, but further limited to devices grown all-epitaxially. When he arrived in 1987 from Bell Labs, he had already been consulting on the installation of our new Gen-II MBE that we intended to use for vertical-cavity Fabry–Pérot

We present an overview of techniques used to pattern the epitaxial growth of quantum dots. Subsequent growth, morphology, and optical characterization are also discussed. The guided assembly of epitaxially grown quantum dots is a research area of great interest in order to enable their use for scalable device applications. The techniques discussed in this review include methods of fabrication and growth

Acquisition and analysis are described for scanning tunneling spectroscopy data acquired from a monolayer of WSe2 grown on epitaxial graphene on SiC. Curve fitting of the data is performed, in order to deduce band edge energies. In addition to describing the details of the theoretical curves used for the fitting, the acquisition and analysis methods are also discussed within the larger context of the

This guide is intended for both the novice in x-ray photoelectron spectroscopy (XPS) as well as users with some experience. XPS is one of the most widely used methods to characterize surface nanostructured samples, and XPS is now also commonly accessible to most material scientists through XPS facility centers. It is, therefore, increasingly used as a routine analysis technique to complement other

Two-dimensional transition metal carbides are promising materials because of their potential for combining the favorable properties of transition metal carbides with the high aspect ratio of two-dimensional materials. Though commonly produced by top-down wet-chemical synthesis methods, synthesis by chemical vapor deposition is being considered because of its ability to achieve large areas, controlled

Interface characteristics of frequency dispersion, flatband voltage (Vfb) shift, fixed charge (QIL), and interface state density (Dit) in β-Ga2O3/Al2O3/Pt capacitors were investigated after postmetallization annealing (PMA) at 300 °C in N2 using a conductance method and a photo-assisted capacitance-voltage technique. After PMA, no frequency dispersion was observed, and the QIL and Dit values related

As the semiconductor industry progresses toward more complex multilayered devices with ever smaller features, accurately aligning these layers with respect to each other has become a bottleneck in the advancement to smaller transistor nodes. To avoid alignment issues, area-selective atomic layer deposition (ALD) can be employed to deposit material in a self-aligned fashion. Previously, we demonstrated

Low volatility precursors are widely utilized in chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes. Compared to gases and high volatility liquid precursors, delivery of low volatility liquid and solid precursors can be problematic, with solid precursors being particularly so. To investigate some of these delivery issues, the performance of a vapor draw vessel was characterized

Selective growth of metal oxides on metal via atomic layer deposition (ALD) has attracted great interest due to their potential applications in the semiconductor industry, as well as energy and environment fields. In this work, the influence of an oxidizing coreactant and the reaction temperature on the selective growth of FeOx on the facets of Pt nanoparticles and low coordination edge sites are studied

The rise of low-temperature atomic layer deposition (ALD) has made it very attractive to produce high- κ dielectric for flexible electronic devices. Similarly, selective deposition of ALD films is of great relevance for circuitry. We demonstrated a simple method of using a physical mask to block the film’s growth in selected polymeric and flexible substrate areas during a low-pressure ALD process.

Atomic layer deposition (ALD) is a technique capable of depositing conformal coatings in highly tortuous 3D nanostructures. One configuration that has attracted attention is nanocrystal (NC) based nanocomposite films, whereby a 3D network of randomly packed nanocrystals is infilled via ALD to yield a dense nanocomposite. In this work, we demonstrate criteria for predicting three important thermal ALD

As part of improving the tribological properties of TiN-based coatings, researchers have introduced additional elements to the binary TiN system. Addition of a self-lubricating and oxide-forming substitutional element such as Mo to the rock salt TiN system deposited by sputtering has been widely studied. But, the TiN-MoN solid solution system grown by atomic layer deposition (ALD) is yet to be reported

The plasma enhanced atomic layer deposition (PEALD) process for MnO2 was demonstrated, exhibiting self-limiting growth as well as stable composition and stable growth rate over a temperature window of 205–265 °C. The PEALD process for MnO2 was combined with the thermal ALD process for LiOH to synthesize Li1+xMn2−xO4 thin film cathodes, where the stoichiometry was effectively controlled to allow for

In this study, we report on the passivation quality of atomic layer deposition grown ultra-thin Al2O3 and Al2O3 capped with plasma-enhanced chemical vapor deposition deposited SiNx on Cz p-type wafers for the rear side of a passivated emitter and rear cell (PERC). Different activation recipes using N2, forming gas (FG), and two-step annealing for different durations are investigated before SiNx deposition

Deposition of titanium nitride thin films by plasma enhanced atomic layer deposition has been realized on thermal silicon oxide substrates in an inductively coupled plasma reactor. The plasma step involves a H2 (40 sccm)/N2 (5 sccm)/Ar (10 sccm) gas mixture, and growth has been followed by in situ ellipsometric measurements. A tunable substrate bias voltage has been applied in the vicinity of the substrate

Gallium nitride (GaN) is one of the most important semiconductor materials in modern electronics. While GaN films are routinely deposited by chemical vapor deposition at around 1000 °C, low-temperature routes for GaN deposition need to be better understood. Herein, we present an atomic layer deposition (ALD) process for GaN-based on triethyl gallium (TEG) and ammonia plasma and show that the process

Vacuum ultraviolet (VUV) enhanced atomic layer etching (ALE) of thin (∼8 nm) Ru films is demonstrated. Oxidation half-cycles of 2–5 min VUV/O2 co-exposure are used to oxidize near-surface Ru to RuO2 at 1 Torr O2 and 100–150 °C. In situ x-ray photoelectron spectroscopy measurements indicate that RuO2 formation saturates after ∼5 min of VUV/O2 exposure at 100 and 150 °C. The depth of Ru oxidation is

The influence of the nitrogen gas ratio on the gallium nitride (GaN) film growth has been investigated using a high-density convergent plasma sputtering device at room temperature. To obtain a highly reactive environment for GaN film growth, the convergent magnetic field lines assist the high-density plasma transport near the target surface. An orthogonal array in the design of experiments was used

The calcium aluminate electride [ Ca 24 Al 28 O 64 ] 4 + ( e − ) 4 (C12A7: e −) is chemically and thermally stable in ambient atmosphere, offers strong electron donating capabilities and exhibits an intrinsic work function of 2.4 eV. Thus, it is an attractive material for electron emitter and low work function applications. For an implementation in negative hydrogen ion sources, where the electride

Plasma-enhanced chemical vapor deposition of silicon from a SiF4/H2/Ar gas mixture is observed on a SiOxNy surface, while under the same plasma conditions, silicon films do not grow on AlOx or on Al surfaces. Transmission electron microscopy confirms that the silicon deposited on SiOxNy has a microcrystalline structure. After the plasma process, fluorine is detected in abundance on the AlOx surface

Although precision in XPS can be excellent, allowing small changes to be easily observed, obtaining an accurate absolute elemental composition of a solid material from relative peak intensities is generally much more problematical, involving many factors such as background removal, differing analysis depths at different photoelectron kinetic energies, possible angular distribution effects, calibration

Plasma-etched micropillars in 4H-SiC were etched in forming gas (4% H2, 96% N2) at 1500, 1550, and 1600 °C at 2.4 and 9.4 standard liters per min (slm). At 2.4 slm, oxygen from the aluminum oxide components of the tube furnace oxidized the SiC surface, and the pillars etched isotropically. At 9.4 slm, the pillars etched crystallographically at 1500 and 1550 °C, and sharp 4H-SiC needless with tips as

The carbon 1s photoelectron spectrum is the most widely fit and analyzed narrow scan in the x-ray photoelectron spectroscopy (XPS) literature. It is, therefore, critically important to adopt well-established protocols based on best practices for its analysis, since results of these efforts affect research outcomes in a wide range of different application areas across materials science. Unfortunately

In this work, a process condition was created to deposit a thin film of diamond on AISI O1 steel in a hot filament chemical vapor deposition (CVD) reactor. The main drawbacks to overcome are the diamond film high residual stresses caused by the difference between the coefficient of thermal expansion (CTE) of steel (∼12 × 10−6 K−1) and diamond (0.8 × 10−6 K−1). Our group proposed a diffusion vanadium

Three-dimensional nanodevice architectures require the coating and filling of deep vias and trenches, leading to an ongoing demand for dry processes with step coverages equal to or greater than one. We describe a new superconformal chemical vapor deposition process based on the use of two precursors: The first precursor readily deposits to afford film growth, but it cannot fill trenches when used alone

The reduction of copper oxide by isopropyl alcohol (IPA) gas and its mechanism were investigated toward the selective process of copper (Cu) wiring. Also, the decomposition behavior of IPA gas and surface modification during the IPA treatment on Cu and copper oxide surfaces were studied. Two samples were measured: Cu surface having native oxide film and a metal Cu surface after a hydrogen reduction

Direct growth of III–V semiconductors on Si promises to combine the superior optoelectronic properties of III–Vs with the existing large-scale fabrication capabilities for Si. Vapor-liquid-solid-based growth techniques have previously been used to grow optoelectronic-quality III–Vs in polycrystalline films and various photolithography-defined features. We show that templated vapor-liquid-solid growth

Epitaxial rhombohedral boron nitride (r-BN) films were deposited on ZrB2(0001)/4H-SiC(0001) by chemical vapor deposition at 1485 °C from the reaction of triethylboron and ammonia and with a minute amount of silane (SiH4). X-ray diffraction (XRD) φ-scans yield the epitaxial relationships of r - BN ( 0001 ) ∥ Zr B 2 ( 0001 ) out-of-plane and r - BN [ 11 2 ¯ 0 ] ∥ Zr B 2 [ 11 2 ¯ 0 ] in-plane. Cross-sectional

The high breakdown voltage and low on-state resistance of Schottky rectifiers fabricated on β-Ga2O3 leads to low switching losses, making them attractive for power inverters. One of the main goals is to achieve high forward currents, requiring the fabrication of large area (>1 cm2) devices in order to keep the current density below the threshold for thermally driven failure. A problem encountered during

In this work, we demonstrate controlled area-selective deposition of aluminum oxide phosphate (AlPO) at room temperature and near atmospheric pressure using a potentially zero-waste aerosol jet fog (ajFOG) deposition system. Octyl-trichlorosilane (OTS-8) self-assembled monolayers (SAMs) are coated on SiO2/Si substrates to form a blanket hydrophobic functionalization. Next, ultraviolet/ozone exposure

Recent breakthroughs in bulk crystal growth of the thermodynamically stable beta phase of gallium oxide (β-Ga2O3) have led to the commercialization of large-area β-Ga2O3 substrates with subsequent epitaxy on (010) substrates producing high-quality films. Still, metalorganic chemical vapor deposition, molecular beam epitaxy, and processing of the (010) β-Ga2O3 surface are known to form subnanometer-scale

In cesium bismuth bromides comprising [BiBr6]3− octahedra, the octahedra behave as quantum dots and their interactions can be manipulated by tailoring their connectedness (e.g., corner-sharing, edge-sharing, or unconnected). Of the four compounds reported, CsBi2Br7, CsBiBr4, Cs3Bi2Br9, and Cs3BiBr6, there is only one publication each on CsBi2Br7 and CsBiBr4. Here, we synthesize CsBi2Br7 and attempt

Single-crystalline aluminum (Al) films are grown on GaAs (100) substrates by molecular beam epitaxy. The Al/GaAs interface is modified by ErAs insertion, and the Al quality is further improved. The full-width at half-maximum for Al (111) diffraction peak is 0.06°, and the root-mean-square surface roughness is 0.69 nm. In addition, the Al growth orientation can be tuned by ErAs insertion, which is attributed

As one of the most attractive transition metal dichalcogenides (TMDs), the growth of molybdenum disulfide (MoS2) with industrial compatibility is of great importance. Atomic layer deposition (ALD) has been shown to be a promising method to achieve the growth of high-quality TMD materials. However, MoS2 films deposited by ALD often are amorphous with nonideal stoichiometry and require high-temperature

Next-generation, energy-dense, rechargeable lithium batteries require Li metal anodes that provide ten times the specific capacity of state-of-the-art graphite anodes. But, there are many challenges to the successful utilization of Li anodes, including high chemical reactivity and the propensity to deposit into non-dense, high surface area morphologies, which can result in dendritic growth and significant

This review discusses critical aspects of patterning phase change materials (PCMs), including dry etching, wet clean, and encapsulation, as they dictate the reliability and functionality of the phase change random access memory devices. Specifically, alloys of germanium–antimony–tellurium are used as a model system, and the importance of PCM composition control, critical dimension control, high fidelity

This review focuses on the physical and chemical vapor deposition methods applied to the preparation of all-inorganic metal halide perovskites. Particular emphasis is devoted to the specific characteristic of the available approaches explored in the current literature for lead-based and lead-free films with also examples of the preparation of microstructure and nanostructure for applications beyond

Alkali metal containing materials have become increasingly attractive in a world hunting for sustainable energy materials and green functional devices. Lithium- and sodium battery technology, lead-free piezo- and ferroelectric devices, and record-breaking alkali doped tandem perovskite solar cells are among the applications where alkali metal-containing thin films get increasing attention. Atomic layer

Magnetron sputtering developed rapidly in the 1980s for semiconductor, hard coating, and architectural glass applications. While the general operating principles were well known, subtle issues relating to cathode material, operating parameters, and deposition processes were only empirically understood. A sequence of magnetron measurements is described, which helps develop a more general understanding

XPS is an important characterization method for epitaxial films and heterostructures. Although standard approaches for XPS data collection and analysis provide useful information such as average composition and the presence of contaminants, more in-depth analyses provide information about the film structure, surface termination, built-in electric potentials, and band offsets. The high degree of structural

Scanning probe microscopes are notoriously sensitive to many types of external and internal interferences including electrical, mechanical, and acoustic noise. Sometimes noise can even be misinterpreted as real features in the images. Therefore, quantification of frequency and magnitude of any noise is the key to discover the source and eliminate it from the system. While commercial spectrum analyzers

The use of peak fitting to extract information from x-ray photoelectron spectroscopy (XPS) data is of growing use and importance. Due to increased instrument accessibility and reliability, the use of XPS instrumentation has significantly increased around the world. However, the increased use has not been matched by the expertise of the new users, and the erroneous application of curve fitting has contributed

This study was undertaken to understand the extent and nature of problems in x-ray photoelectron spectroscopy (XPS) data reported in the literature. It first presents an assessment of the XPS data in three high-quality journals over a six-month period. This analysis of 409 publications showing XPS spectra provides insight into how XPS is being used, identifies the common mistakes or errors in XPS analysis

Transition metal dichalcogenides (TMDs) are promising electrocatalysts for the hydrogen evolution reaction (HER). Several approaches have been adopted to increase the density of the catalytically active edge-sites of TMDs including the use of high surface area 3D templates. In this work, we report the implementation of a high surface area WS2 framework grown using plasma-enhanced atomic layer deposition

Using the first-principles calculations and combining with the phonon Boltzmann transport equation, we systematically investigated the phonon thermal transport properties of II–VI group graphenelike materials (BeO, MgO, CaO, SrS, and SrSe). The lattice thermal conductivities κ L’s of 118.68, 42.48, 11.13, 3.33, and 3.09 W/mK are obtained at 300 K in BeO, MgO, CaO, SrS, and SrSe, respectively, which

Atomic layer deposition (ALD) of ruthenium is of interest for various applications in nanoelectronics and is currently gaining attention for its potential role in interconnect technology in future technology nodes. This work provides insights into the influence of the O2 pulse time on the film nucleation on SiO2 and on the resulting material properties. Ru thin films were deposited using a three-step

Aluminum oxide films deposited by spatial atomic layer deposition have been used for thin-film encapsulation of organic light-emitting diodes. In this study, a multidensity layer structure consisting of two Al2O3 layers of different densities was deposited at varying ozone flow rates. The structure improved moisture permeation barrier characteristics, as confirmed by the water vapor transmission rate

Atomic layer deposition (ALD) is used to systematically vary the composition of TiSixN films by modulating the ratio of Ti and Si precursors with NH3 as a coreactant. The as-synthesized films have varying atomic (at.) % Si (0 ≤ x ≤ 24.2) to provide both metallic (i.e., TiN) and insulating (i.e., Si3N4) behavior. The competing material properties reduce the temperature coefficient of resistivity (TCR)

Room temperature evaporation of titanium isopropoxide [Ti[OCH(CH3)2]4, TTIP] precursor was performed using ultrasonic atomization for TiO2 atomic layer deposition (ALD). Quartz crystal microbalance data show comparable results between room temperature TTIP ultrasonic atomization and conventional thermal evaporation. The TiO2 ALD saturation window is established for room temperature atomized TTIP exposure

Self-limiting character of the involved surface reactions is essential for highly uniform and conformal growth in atomic layer deposition (ALD). However, the poor conformal coverage (<75%) that is often reported with silicon nitride (SiNx) plasma enhanced ALD (PEALD) processes using metalorganic Si-precursors is confounding. In this article, we report our study of the SiNx PEALD process using the tris-dimethylamino

In this work, we have studied the influence of N2/H2 plasma gas flow rates on the hollow-cathode plasma-assisted atomic layer deposition (HCPA-ALD) growth of indium nitride (InN) films. The influence of N2/H2 plasma gas flow rates on crystallinity, lattice distortion, phonon properties, and bandgap was analyzed. We found that the strain can be relieved fully or partially through the incorporation of

Ultrahigh purity (UHP) reactor conditions provide a process environment for growth of nitride thin films with low oxygen content by plasma-enhanced atomic layer deposition (PEALD). In particular, UHP conditions correspond to partial pressures below 10−8 Torr for impurities within the PEALD process environment to limit incorporation before, during, and after film growth. In this article, we identify

β-Ga2O3 films are deposited on (0001) sapphire substrates using triethylgallium (TEGa) and nitrous oxide (N2O) under high N2O/TEGa ratios by atomic layer deposition (ALD). Au-β-Ga2O3-Au metal/semiconductor/metal (MSM) solar-blind deep ultraviolet (DUV) photodetectors (PDs) are prepared using Au interdigitated electrodes deposited by thermal evaporation. The ALD-grown β-Ga2O3 films and Au-β-Ga2O3-Au

The initial growth of silicon nitride (SiN) thin films was studied during thermal atomic layer deposition (ALD) using silicon tetraiodide (SiI4) and ammonia (NH3) onto various oxide underlayers (native SiO2, sapphire, ALD Al2O3, and ALD ZrO2) at two deposition temperatures (200 and 350 °C). We found that the SiI4/NH3 process shows earlier nucleation on high-k oxide underlayers (sapphire, ALD Al2O3

In this work, we investigate the atomic layer deposition (ALD) of ZrO2 thin films on Cu and SiO2 substrates, using Zr[N(C2H5CH3)]4 as the thin-film precursor, and H2O or O2 as the coreactants. Here, we introduce 3-hexyne as a coadsorbate molecule during the thin-film precursor half-cycle and examine its effect on the selectivity of growth. We find that 3-hexyne strongly inhibits growth on Cu, while

There is presently a critical need for a viable approach to form ultrathin, high-quality layers of oxides such as Al2O3 on MoS2 and related two-dimensional transition-metal chalcogenides. Atomic layer deposition (ALD), which is, in principle, the most suitable technique, has been problematic in this case as a result of the low reactivity of these substrates when free of strain, impurities, and defects

Atomic layer etching (ALE) enables atomic-precision control of the surface reaction for device fabrication. In this study, we investigate SiN ALE with process optimization of the surface adsorption and desorption steps, and we clarify the rate fluctuation mechanism. When we attempted CH3F/Ar plasma adsorption followed by the subsequent Ar desorption step, an etch stop was observed owing to the excess

Nanorod arrays have become an attractive alternative to their thin film and bulk counterparts in photovoltaic and photoconductivity research. This is mainly attributed to their superior optical and electrical properties. Light trapping and unique bandgap geometries in vertically aligned nanostructures result in high optical absorption and provide enhanced carrier collection by utilizing a fully depleted

In this work, the optical response of the gold nanoparticles is used for low-damage nitridation of graphene over a graphite substrate. Nitrogen-doped graphene with high two-dimensional crystallinity is successfully formed via radicals and light from a low-temperature, low-pressure, inductively coupled argon-diluted ammonia plasma. The graphene over a graphite substrate is covered with gold nanoparticles