Abstract The value of exchange energy for near-surface double-donor and double-quantum dot structures under the effect of external electric field has been calculated using unrestricted Hartree–Fock method. The dependences of exchange energy on geometric parameters have been obtained. It has been found that the location of donor centers near the surface of the semiconductor leads to an increase in the

Abstract The electron spectrum in a uniform nanowire with a hexagonal cross-section is calculated by means of a numerical diagonalization of the effective-mass Hamiltonian. Two basis sets are utilized. The wave-functions of low-lying states are calculated and visualized. The approach has an advantage over mesh methods based on finite-differences (or finite-elements) schemes: non-physical solutions

Abstract In this work, we applied automatic design generation techniques to obtain the most efficient quantum cascade laser (QCL) structures for the mid-infrared range. For simulations, the transfer matrix, ensemble Monte Carlo and density matrix techniques, accelerated with CUDA computation technology, were utilized. As a result, several designs were created using the modification of the genetic algorithm

Abstract It is shown theoretically, that the phenomenon of radiation focusing in a small region of the near zone inside a dielectric film can present due to electromagnetic wave transmission through sub-wavelength nanoapertures. The confirmation is based on the rigorous theory of plane wave diffraction by a slot in a perfectly conducting screen of finite thickness in the presence of a plane dielectric

Abstract During the self-catalyzed GaAs nanowire growth formation of parasitic GaAs crystallites is observed. The reasons for crystallite formation are explained on the base of Monte Carlo simulation results. During simultaneous deposition of gallium and arsenic on the GaAs(111)B substrate coated by a silicon oxide film, liquid gallium droplets nucleate on the oxide surface. After nucleation, droplets

Abstract Investigation of GaN epitaxial layers on silicon substrates is driven by high potential for fabrication of high efficiency and relatively low-cost electronic devises. Growth process of GaN layers on Si by molecular-beam epitaxy is complicated by mutual diffusion of Si and Ga and differences in thermal expansion coefficients and lattice parameters causing large number of defects. To improve

Abstract In this work, a versatile method to increase the optical response of oxide nanostructures is described. Thin TiO2 films with buried gold nanoparticles (TiO2-AuNP) were synthesized on a crystalline Si surface. The localized surface plasmon resonance reflection maximum is formed around 720–750 nm. Current-voltage characteristics of planar structures formed by use of different contact materials

Abstract The Ag/Ge/Si(001) stacks with threading dislocations growing through the Ge epitaxial layers (ELs) manifested bipolar resistive switching (RS) between two metastable resistance states. Scanning transmission electron microscopy (STEM) provided a direct evidenced the RS mechanism to consist in the electrodiffusion of Ag+ ions along the dislocations in the Ge ELs. Also, STEM revealed multiple

Abstract Passivation of the n-InP(100) surface with sodium sulfide (Na2S) aqueous solution is analyzed by photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). The room-temperature PL intensity increases essentially even after short treatment with sulfide solution for 1 min. The enhancement in the room-temperature PL intensity after passivation decreases with the increase in the bulk doping

Abstract The structural and magnetic properties of FeCo–C films produced by electroless plating with different carbohydrates as reducing agents have been investigated. The surface morphology and coercivities of FeCo–C films are dependent on the iron content and type of reducing agent. The local magnetic anisotropy field value increases with a decrease in Fe content. For all systems, deposits with good

Abstract The feature of the promising tool of lithographic nanostructuring based on selective exposure of polymer resist by ion beam is very compact (of about tens of nanometers) beam interaction volume. Herewith the main part of beam energy is deposited in the resist and is spent to its modification. It causes the set of advantages specific for this method: sub-10 nanometer resolution achievable,

Purpose The purpose of this study is the design, fabrication and evaluation of a miniature ozone generator using the principle of electric discharge are presented. Design/methodology/approach The device was fabricated using a low-temperature co-fired ceramics (LTCC) technology, by which a multilayered ceramic structure with integrated electrodes, buried channels and cavities in micro and millimeter

Abstract—The influence of the supply voltage and temperature on the characteristics of the photoresponse of silicon photoelectric multipliers has not been adequately studied. In this study, the influence of these factors on the time characteristics of the photoresponse of silicon photoelectric multipliers is investigated. A block diagram of the experimental system is presented. In the system, the optical

Spin-devices are switched by flipping spins without moving charge in space and this can lead to ultra-low-energy switching replacing traditional transistors in beyond Moore’s law era. In particular, the electric field-induced magnetization switching has emerged to be an energy-efficient paradigm. Here, we review the recent developments on ultra-low-energy, area-efficient, and fast spin-devices using

The continuous downscaling in CMOS devices has increased leakage power and limited the performance to a few GHz. The research goal has diverted from operating at high frequencies to deliver higher performance in essence with lower power. CMOS based on-chip memories consumes significant fraction of power in modern processors. This paper aims to explore the suitability of beyond CMOS, emerging magnetic

The magnetic properties of amorphous Co100−xZrx films prepared by co-evaporation have been studied by means of vibrating sample magnetometry and ferromagnetic resonance. The temperature dependence of spontaneous magnetization Ms in the low temperature range can be described using Bloch’s law. In addition, the spin wave stiffness constant, the distance between nearest magnetic atoms and the exchange

Research Highlights • Electronic, magnetic, elastic and thermoelectric properties of RbCrC alloy are investigated. • Material is half-metallic, ductile and anisotropic in nature. • The total magnetic moment (3μB) obeys the Slater–Pauling rule. • The HM RbCrC compound is identified as potential candidate for spintronic applications. • ZT calculated values of 0.89 and 0.94 make RbCrC a promising thermoelectric

The influence of mild thermal annealing and nickel addition on the magnetic properties of Co–CoO multilayers is investigated. Co–CoO and CoNi–CoNiO multilayers were fabricated by radio-frequency magnetron sputtering and natural oxidation. Their magnetic properties have been studied via the magneto-optical Kerr effect and a vector network analyzer ferromagnetic resonance setup. The Co–CoO multilayers

The structural, elastic, electronic and magnetic properties of quaternary OsCrMnSb and IrCrMnSb Heusler alloys are performed employing ab initio electronic structure calculations. It has been identified that the YI type is the most stable structure among the three configurations for both OsCrMnSb and IrCrMnSb alloys in the magnetic state. The calculated cubic elastic constants show that these alloys

Purpose Optimization of light-emitting diodes’ (LEDs’) design together with long-term reliability is directly correlated with their photometric, electric and thermal characteristics. For a given thermal layout of the LED system, the maximum luminous flux occurs at an optimal electrical input power and can be determined using a photo-electro-thermal (PET) theory. The purpose of this study is to extend

We investigate the hot carrier injection effect (HCI) and how X-ray radiation impacts the HCI of 22-nm nFinFETs as a function of device geometry and irradiation bias conditions in this paper. In the HCI test, the degradation of threshold voltage and saturation current decreases with the increase of fin number, which means that HCI weakens when the fin number increases. The reason is attributed to the

The radio-frequency (RF) performance of the p-type NiO-pocket based β -Ga 2 O 3 /black phosphorous heterostructure MOSFET has been evaluated. The key figure of merits (FOMs) for device performance evaluation include the transconductance ( g m ) gate dependent intrinsic-capacitances ( C gd and C gs ), cutoff frequency ( f T ), gain bandwidth (GBW) product and output-conductance ( g d ). Similarly, power-gain

High-quality AlN/sapphire templates were fabricated by the combination of sputtering and high-temperature (HT) annealing. The influence of sputtering parameters including nitrogen flux, radio frequency power, and substrate temperature on the crystalline quality and surface morphology of annealed AlN films were investigated. With lower substrate temperature, lower power, and lower N 2 flux, the full

Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation. The activation rate refers to the ratio of activated impurity number to the total impurity number in the sample. After injecting phosphorus with the dose and energy (energy = 55 keV, dose = 3 × 10 15 cm –2 ), the samples were annealed at different temperatures, and laser irradiation

In this paper, a 16-bit 1MSPS foreground calibration successive approximation register analog-to-digital converter (SAR ADC) is developed by the CMOS 0.25 μ m process. An on-chip all-digital foreground weights calibration technique integrating self-calibration weight measurement with PN port auto-balance technique is designed to improve the performance and lower the costs of the developed SAR ADC.

Three small molecule (SM) donors, namely B-T-CN, B-TT-CN and B-DTT-CN, with different π conjugated bridges were synthesized in this research. Interestingly, with the conjugated fused rings of the π linking bridge increasing, the SM HOMO levels exhibit a decline tendency with –5.27 eV for B-T-CN, –5.31 eV for B-TT-CN and –5.40 eV for B-DTT-CN. After blending the SM donors with the fullerene acceptor

Compared to the conventional phase change materials, the new phase change material Ta-Sb 2 Te 3 has the advantages of excellent data retention and good material stability. In this letter, the etching characteristics of Ta-Sb 2 Te 3 were studied by using CF 4 /Ar. The results showed that when CF 4 /Ar = 25/25, the etching power was 600 W and the etching pressure was 2.5 Pa, the etching speed was up

Abstract One of the most promising platforms to implement quantum technologies are coupled electron-nuclear spins in diamond in which the electrons of paramagnetic color centers play a role of “fast” qubits, while nuclear spins of nearby 13C atoms can store quantum information for a very long time due to their exceptionally high isolation from the environment. Essential prerequisite for a high-fidelity

Abstract In this paper, we investigate the features of reflection of a plane elliptically polarized electromagnetic wave fallen from isotropic transparent dielectric on a layer of hyperbolic metamaterial with optical axis in an interface and main effective dielectric permittivities less than the permittivity of dielectric. The cases are analyzed when one (ordinary or extraordinary) wave or two waves

Abstract Using the semi-empirical quantum chemical PM3 method the energies of carbon nanoscrolls formed from flat zigzag graphene nanoribbons 46zGNR and 70zGNR are calculated. For this purpose a simple algorithm to define the Cartesian coordinates of the atoms of a carbon nanoscroll is proposed. The dependences of the energy of the nanoscrolls relative to the energy of the corresponding flat nanoribbon

Abstract We predict the characteristics of hyperfine interactions (hfi) for a number of electron-nuclear spin systems NV-13C in diamonds grown by seeding approach from the specific isotopic aza-adamantane or methyl-aza-adamantane molecules differing in 13C position in the precursor as well as in the orientation of the NV center in the post-obtained diamond. For the purpose we have used the spatial

Abstract A new approach for calculating the ion dose spatial distribution of the focused ion beam is proposed. The approach is based on the analysis of the secondary electron microscopy image of the area irradiated by the focused ion beam.

Abstract Magnetostatic surface waves (MSSW) propagation and electromotive force (EMF) generation effects in 14.6 µm-thick yttrium iron garnet (YIG) film covered by 8 nm-thick Pt layer was studied. It was found that MSSW dispersion k = k(f) and transmission S21(f) characteristics in the YIG/Pt structure are very similar to that of the free YIG film. For YIG/Pt structure, we show that EMF (U) demonstrates

Abstract Electronic structure of molybdenum oxides obtained by the oxidation of molybdenum at an oxygen pressure of 1 Torr (thin film) and air (thick film) was studied. It was shown that a thick oxide film is formed from MoO3 oxide, and a thin film from a mixture of MoO3 and MoO2 oxides, which is reflected in the form of valence band spectra. Oxygen on the surface belongs both in molybdenum oxide and

Abstract The structural and some other characteristics of quasi-freestanding single-layer graphene obtained by annealing of the buffer layer in the flow of hydrogen are studied in comparison with those of conventional epitaxial graphene. The high structural quality and good lateral uniformity of the thus-obtained graphene film are checked and confirmed by the use of such techniques as Raman spectroscopy

Abstract Ferromagnetic resonance was used to study three types of ferrihydrite nanoparticles: nanoparticles formed as a result of the cultivation of microorganisms Klebsiella oxytoca; chemically prepared ferrihydrite nanoparticles; chemically prepared ferrihydrite nanoparticles doped with Cu. It is established from the ferromagnetic resonance data that the frequency-field dependence (in the temperature

Abstract The “germanium-vacancy” (GeV) center in diamond can be used as Temperature Sensors. The idea of GeV-based thermometry is based on optical measurements of the spectral shift of the zero-phonon line and its spectral width as a function of temperature changes. At the same time optical characteristics of GeV center which is located near-surface could be modified by formation of defect states in

Abstract Polymer nanocomposites based on Cu(Cu2O)-LDPE with a volume fraction of 0.1–0.4 copper filler in the form of spherical nanoparticles with sizes from 10 to 25 nm were synthesized. The electrical conductivity of such composite nanomaterials was measured, which is 4.5–5 times higher than the electrical conductivity of a polyethylene matrix. To predict the electrical conductivity of such materials

Abstract We report the results of systematic experimental and theoretical studies of structural and dynamical properties of short-period GaN/AlN superlattices. The multilayer structures with the thicknesses of the constituent layers varying from two to several monolayers are grown using the submonolayer digital molecular beam epitaxy technique. In the framework of density functional theory, the lattice

Abstract Forward and reverse current–voltage characteristics of commercial rectifier diodes based on a Schottky barrier to 4H-SiC are studied in the temperature range 20–370°C at a maximum current of 10–20 mA and maximum voltage of 10–100V. It is found that the diodes can be considered nearly ideal with a Schottky-barrier height of ~1.5 eV, with the forward current over the entire temperature range

Abstract The magnetic moment of the unmodulated bilayer graphene is calculated in the presence of a perpendicular magnetic field B. The oscillatory character of the magnetic moment dependences on the magnetic field is investigated.

Abstract Recently Ma et al. (Nature Nanotech. 14, 145, 2019) reported an intrinsic photocurrent in graphene, which occurs as the authors believe “in a different parameter regime from all the previously observed photothermoelectric or photovoltaic photocurrents in graphene”. Here we present an alternative – obvious and transparent explanation of such experiments. We demonstrate that the photo effect

Abstract Raman spectroscopy is used to evaluate the structural perfection of epitaxial graphene films before and after deposition of a Ni layer to their surface by magnetron sputtering. Two deposition modes with different gas pressures and deposition times are investigated. It is found that Ni deposition under low pressure combined with long deposition time does not lead to the separation of graphene/Ni

Abstract A MoS2 sheet in its 1T ' phase is a two-dimensional topological insulator. It possesses highly conductive edge states which, due to topological protection, are insensitive to back scattering and are suitable for device channels. A transition between the topological and conventional insulator phases in a wide 1T '-MoS2 sheet is controlled by an electric field orthogonal to the sheet. In order

Abstract We consider the construction of exactly solvable models of twisted carbon nanotubes by applying Darboux transformation to the square of the Dirac-like Hamiltonian, describing the low-energy dynamics of charge carriers. It is shown that obtained two pseudo-Schrodinger expressions are intertwined, demonstrating supersymmetry structure. It is proved, that for the considered class of pseudo-scalar

Abstract We found bulk n-GaAs layers grown by liquid phase epitaxy to be irregularly stressed. Deformation created by this stress causes a small but detectable quadrupole splitting of Zeeman nuclear energy levels. In our work we detected a very weak quadrupole splitting for 69Ga and 75As isotopes in bulk n-GaAs and obtained the value of the sample deformation. To this end, we used a new method that

Abstract Applying the conventional Floquet theory of periodically driven quantum systems, we developed the theory of optical control of structures based on gapless semiconductors. It is demonstrated that electronic properties of the structures crucially depends on irradiation. Particularly, irradiation by a circularly polarized electromagnetic wave lifts spin degeneracy of electronic bands and induces

This paper proposes a technique that uses the number of oscillation cycles (NOC) of a VCO-based comparator to set multiple adaptive bypass windows in a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC). The analysis of the number of bit cycles, power and static performance shows that three adaptive bypass windows reduce power consumption, and decrease DNL and have similar

Realizing the layouts of analog/mixed-signal (AMS) integrated circuits (ICs) is a complicated task due to the high design flexibility and sensitive circuit performance. Compared with the advancements of digital IC layout automation, analog IC layout design is still heavily manual, which leads to a more time-consuming and error-prone process. In recent years, significant progress has been made in automated

FMCW radars with high resolution necessities the generation of highly linear, low phase noise, and low spur chirp signals with large bandwidth and a short modulation period. This paper reviews recent research progress on silicon-based FMCW signal generators, identifies advances in architecture, fundamental design, performance analysis, and applications of the FMCW synthesizer.

A 30 MHz voltage-mode controlled buck converter with fast transient responses is presented. An improved differential difference amplifier (DDA)-based Type-III compensator is proposed to reduce the settling times of the converter during load transients, and to achieve near-optimal transient responses with simple PWM control only. Moreover, a hybrid scheme using a digital linear regulator with automatic

Digital to analog converters (DAC) play an important role as a bridge connecting the analog world and the digital world. With the rapid development of wireless communication, wideband digital radar, and other emerging technologies, better performing high-speed high-resolution DACs are required. In those applications, signal bandwidth and high-frequency linearity often limited by data converters are

Granular power management in a power-efficient system on a chip (SoC) requires multiple integrated voltage regulators with a small area, process scalability, and low supply voltage. Conventional on-chip analog low-dropout regulators (ALDOs) can hardly meet these requirements, while digital LDOs (DLDOs) are good alternatives. However, the conventional DLDO, with synchronous control, has inherently slow

With the development of multi-band wireless communication and the increasing data transmission rate, the circulator as an antenna interface must be able to work in multiple frequency bands and provides large bandwidth. It presents a high challenge to the design of circulators, especially the active quasi-circulators. In this survey, we review the representative active quasi-circulators and summarize

The successive approximation register (SAR) is one of the most energy-efficient analog-to-digital converter (ADC) architecture for medium-resolution applications. However, its high energy efficiency quickly diminishes when the target resolution increases. This is because a SAR ADC suffers from several major error source, including the sampling kT / C noise, the comparator noise, and the DAC mismatch

CMOS analog and mixed-signal phase-locked loops (PLL) are widely used in varies of the system-on-chips (SoC) as the clock generator or frequency synthesizer. This paper presents an overview of the AMS-PLL, including: 1) a brief introduction of the basics of the charge-pump based PLL, which is the most widely used AMS-PLL architecture due to its simplicity and robustness; 2) a summary of the design

Abstact —We study spin-valley relaxation dynamics in two-dimensional MoxW1–xSe2/WSe2 heterobilayers with different relative Mo/W concentration x in the monolayer alloy. Three types of heterobilayers with x = 1.00, 0.50, 0.33 are studied in time-resolved Kerr rotation experiments for different wavelengths and temperatures. The spin-valley relaxation times are found to decrease from ~10 nanoseconds for

Abstract Theory of plasmon-exciton coupling is developed for a metal nanocylinder grating located in the vicinity of a semiconductor quantum well. In dipole approximation, the effective polarizability of cylinders is derived, taking into account generation of quantum-well excitons in the near field of surface plasmons. Given the polarizability, the spectra of reflection and absorption are calculated

Abstract Films of the composition Ba0.8Sr0.2TiO3 (BST 80/20) are synthesized on a silicon substrate by the method of the high-frequency sputtering of a polycrystalline target. The results of investigations of the film composition, the electrophysical properties of capacitor structures based on them, and the dependence of these properties on the material (Al, Cu, Ni, Cr) of the upper electrode are presented

Abstract In this work, drain current ID for 7-nm gate length dual-material (DM) cylindrical gate all around (CGAA) silicon nanowire (SiNW) has been studied and simulation results are reported using Silvaco ATLAS 3D TCAD. In this device, we consider the non-equilibrium Green’s function (NEGF) approach and self-consistent solution of Schrödinger's equation with Poisson’s equation. The splitting of conduction