GaAs Semiconductor Research Articles

Remarks on the Study of the Electronic Properties and Photoionization Process in Rotating 2D Quantum Rings

The electronic and optical properties of a mesoscopic heterostructure of a two-dimensional quantum ring composed of Gallium Arsenide (GaAs) semiconductors are investigated. Using the confinement potential proposed by Tan and Inkson to describe the system under analysis, we conducted a numerical study of the photoionization cross-section for a 2D quantum ring with and without rotation effects. The interior of the quantum ring is traversed by an Aharonov–Bohm (AB) flux. Our research aims to investigate how this mesoscopic structure’s electronic and optical properties respond to variations in the following parameters: average radius, AB flux, angular velocity, and incident photon energy. Under these conditions, we establish that optical transitions occur from the ground state to the next excited state in the conduction subband, following a specific selection rule. One of the fundamental objectives of this study is to analyze how these rules can influence the general properties of two-dimensional quantum rings. To clarify the influence of rotation on the photoionization process within the system, we offer findings that illuminate the effects of the pertinent physical parameters within the described model. We emphasize that, although this is a review, it provides critical commentary, analysis, and new perspectives on existing research. Some results presented in this paper can be compared with those in the literature; however, new physical parameters and quantum ring configurations are used.

First-principles investigation of electronic, magnetic, and optical properties of FeMnSb/GaZ (Z = As or P) interfaces

We systematically investigated the electronic, magnetic, and optical properties of the FeMnSb half-Heusler alloy, its (001) surface, and its interfaces with GaAs and GaP semiconductors by using first-principles calculations based on density functional theory. The bulk FeMnSb reveals its half-metallic ferrimagnetism with 100% spin-polarization. Extending this study to the (001) surface, we uncover distinct electronic and magnetic behaviors for Fe- and MnSb-terminated surfaces, the MnSb-terminated surface preserving the half-metallicity observed in the bulk material. Our evaluation of the interfaces exhibits positive work of separation, indicating that these interfaces are energetically favorable. The density of states analysis reveals that all interfaces exhibit a metallic nature. High spin-polarization values, particularly 97.316% for the Fe-Ga interface, suggest a substantial degree of spin-polarized current. Notably, the absorption coefficient peaks shift from the ultraviolet (UV) region in the bulk alloy to the visible region at the (001) surfaces. However, at the FeMnSb/GaAs and FeMnSb/GaP interfaces, the highest absorption peaks revert to the UV region, highlighting strong interfacial coupling effects. These results suggest the tunability of FeMnSb optical properties via surface termination and interface engineering, making it a promising candidate for spintronic and optoelectronic applications.

LSTM-based framework for predicting point defect percentage in semiconductor materials using simulated XRD patterns

In this paper, we present a machine learning-based approach that leverages Long Short-Term Memory (LSTM) networks combined with a sliding window technique for feature extraction, aimed at accurately predicting point defect percentages in semiconductor materials based on simulated X-ray Diffraction (XRD) data. The model was initially trained on silicon-simulated XRD data with defect percentages ranging from 1 to 5%, enabling it to predict defect percentages from 0 to 10% in silicon and other semiconductor materials, including AlAs, CdS, GaAs, Ge, and ZnS. Through extensive experimentation, we explored different sequence lengths and LSTM units, identifying the optimal configuration as a sequence length of 3501 and 4500 units, which yielded the best results. The model’s mean absolute error at 4500 units was 0.021, the lowest among the LSTM configurations tested. The sliding window technique plays a crucial role in capturing temporal dependencies within the XRD data, allowing the model to generalize to other semiconductor materials. Additionally, we observed that increasing defect percentages consistently led to a rise in background intensity. We further examined the relationship between crystal structure and defect precentage predictions, uncovering consistent trends for materials with Diamond Cubic and Zinc Blende structures. This LSTM-based method offers a novel approach to predicting defect percentages using simulated XRD patterns of materials.

Tailoring electronic structure and thermodynamic stability of (Al, In)-substituted GaAs: Ab-initio insights into bulk and (001) surfaces

Ab-initio calculations are conducted to investigate the structural properties, electronic structure, and thermodynamic stabilities of bulk and (001) surface systems of the GaAs semiconductor in its zinc-blende crystal phase. For the bulk case, we focus on the impact of substituting gallium atoms with M atoms (M = Al, In) at various concentrations (5.55 %, 11 %, and 22 %). We present the resulting structural parameters, along with the formation and substitutional energies associated with these substitutions. For surface systems, we explore indium (In) or aluminum (Al) substitutions at coverages of 0.25, 0.50, and 1.0 monolayers. This includes investigating the effects of substituting M atoms within the first atomic layer of the slabs. Ab-initio thermodynamic calculations reveal that high Al substitutions, in both bulk and surface, result in more favorable formation and surface energies. In contrast, In substitutions exhibit the opposite behavior, with increasing In content leading to less favorable energetics. Moreover, density of states analysis reveals that bulk systems maintained a semiconducting character, while all studied surface configurations exhibited a metallic electronic behavior. This study provides valuable insights into the influence of Al and In substitutions on the structural, electronic, and thermodynamic properties of GaAs, both in bulk and on the (001) surface.

A study on develop the High-Performance Wide - Band LNA for use with IEEE frequency

In this research, a low-noise amplifier (LNA) with uniform growth, silent operation, and absolutely brilliant uniformity is suggested to be utilized in bandwidth transmitters, with a comparative channel capacity (RBW) of 110%. To enhance extended the reach, researchers present a cascode with dual feedbacks and a wide bandpass (BPDWB) matching network formed from bias and parasitic characteristics. The techniques for constructing a corresponding networking are also shown, and measurements indicate that the channel's resonance frequency is a great pairing for the required resistance in the range from through 3.5 GHz. Resistance matched precision and efficiency in prediction are both boosted by the envisaged BPDWB networks. Paper presents a low amplifiers (LNA) in 0.25 m GaAs father made high mobility electrons semiconductor (GaAs pHEMT) developers and researchers NF0.55 at mhz. Additionally, for the range of frequency of 8.5-20 MHz, overall bit error rate (NF) is somewhere between 2.19 to 3.23 dB, while another NF maximum (vase: internet: mia2bf00852: mia2bf00852-math-0012) varied between 1.55 - 2.91 db. At top of just that, a two-tone test with a frequency separation of 50 MHz demonstrates that the suggested LNA may accomplish high IIP3 of 0.96 frequency range.

HYBRID METAL-SEMICONDUCTOR STRUCTURES BASED ON InP AND GaAs NANOTEMPLATES FOR ELECTRONIC AND PHOTONIC APPLICATIONS

In this scientific work are presented the results that contribute to solving an important scientific problem related to obtaining of porous templates with controlled morphology and design by replacing acidic and alkaline electrolytes, the use of which presents a danger for the environment, with neutral electrolyte (NaCl) as well as obtaining of the metal-semiconductor hybrid structures using pulsed electrodeposition that offers additional possibilities to control the localized deposition in certain portions of the porous template and allows the controlled fabrication of nanodots, nanowires, nanotubes and perforated metal nanomembranes. Mechanisms of pore propagation in InP and GaAs semiconductor substrates and electrochemical deposition of metals in the produced porous templates are identified and discussed, which allowed to control the direction of pore growth, including those parallel to the substrate surface as well as localized Au deposition.

Real, imaginary and complex branches of Lamb waves in p-type piezoelectric semiconductor GaAs plate: Numerical and experimental investigation

First, we experimentally measure the concentration of holes of the piezoelectric semiconductor (PSC) Gallium arsenide (GaAs) material based on the Hall effect measurement. We then numerically calculate the Lamb wave characteristics in a p-type PSC GaAs plate using this measured value of the concentration of holes (estimated at approximately p0=3.5431×1025m−3). To guarantee the coupling effect that makes the Lamb wave a piezo-active wave, the GaAs crystal is oriented in a specific orientation of (110) plane. Ordinary differential equation (ODE) method is employed to calculate the dispersion curves, 3D view of the mechanical displacements, 3D view of the electric potential and 3D view of the concentrations of holes. Results show that the appearance of the complex branches of the Lamb modes coincides with the vanishing of the imaginary part of the wavevector (Im(k1)) to zero, which is a very remarkable finding that has not been discussed in previous studies. Meanwhile, these complex branches start exactly at the point of Zero-group-velocity (ZGV). Moreover, the present work highlights the hole drift characteristics of PSC GaAs and provides a critical comparative discussion with those published by (Zhu et al., 2018) for the PSC ZnO plate. Accordingly, the “Screening effect” phenomenon that is based on the positive holes in the negative electric potential region is discussed. The present results provide a theoretical and fundamental guidance on the development of smart devices based on the PSC GaAs material.

Spin-dependent interactions in orbital-density-dependent functionals: Noncollinear Koopmans spectral functionals

The presence of spin-orbit coupling or noncollinear magnetic spin states can have dramatic effects on the ground-state and spectral properties of materials, in particular on the band structure. Here, we develop noncollinear Koopmans-compliant functionals based on Wannier functions and density-functional perturbation theory, targeting accurate spectral properties in the quasiparticle approximation. Our noncollinear Koopmans-compliant theory involves functionals of four-component orbital densities that can be obtained from the charge and spin-vector densities of Wannier functions. We validate our approach on four emblematic nonmagnetic and magnetic semiconductors where the effect of spin-orbit coupling goes from small to very large: the III-IV semiconductor GaAs, the transition-metal dichalcogenide WSe2, the cubic perovskite CsPbBr3, and the ferromagnetic semiconductor CrI3. The predicted band gaps are comparable in accuracy to state-of-the-art many-body perturbation theory and include spin-dependent interactions and screening effects that are missing in standard diagrammatic approaches based on the random phase approximation. While the inclusion of orbital- and spin-dependent interactions in many-body perturbation theory requires self-screening or vertex corrections, they emerge naturally in the Koopmans-functionals framework. Published by the American Physical Society 2024

Preparation and Electrical Performance Analysis of a GaAs‐Based Tritium Battery

A nuclear battery is a promising candidate for small power supply sources in the military and commercial fields, but its output power and energy conversion efficiency need to be improved. This paper mainly describes a design, preparation, and electrical performance analysis of a GaAs-based tritium battery. The design of the tritium battery uses a multistage process with Monte Carlo and Matlab simulations. A titanium tritide source was prepared by a high-temperature tritium absorption device, and a GaAs semiconductor transducer was developed using a metal-organic chemical vapor deposition method. The D/Ti ratio and T/Ti ratio of the deuterium/tritium titanium films were 1.9 and 1.7, respectively. Two kinds of GaAs-based PIN junction semiconductor transducers were proposed and irradiated with the prepared tritium source. Their electrical properties were measured in situ and analyzed qualitatively. Under the irradiation of a 0.61-Ci tritium source, the short-circuit current of the device was 0.3 to 0.38 μA, the open-circuit voltage was 35 to 63 mV, the peak power was 2.8 to 6.4 nW, and the energy conversion efficiency of the GaAs semiconductor transducer was about 1.86%. It was found that an air gap between the GaAs semiconductor transducer and the radioactive source caused serious loss of beta particle energy, resulting in low output power and low energy conversion efficiency of the nuclear battery. The open-circuit voltage of the devices with a SiO2 passivation layer on the surface decreased both in a dark environment and in light illumination, but SiO2 passivation did not reduce surface recombination as expected. The research work in this paper will provide some valuable reference for the preparation and performance optimization of nuclear batteries.

Rapid oxidation of semiconductors at room temperature with a basic plasma cleaner

This paper shows how a simple modification of the electrodes in a basic commercial plasma cleaner allowed the oxidation of compound semiconductors (GaAs) and Si at room temperature. We explained the oxidation of the semiconductor surface by the participation of aluminum atoms evaporated from the electrode surface in the discharge, which resulting in additional ultraviolet (UV) radiation from the plasma. The UV radiation not only increases the decomposition of oxygen molecules adsorbed on the surface but also results in photoionization of GaAs with the formation of Ga and As ions at the oxide–GaAs interface. In addition to obtaining oxides on semiconductor surfaces, the modified device proved to be an effective tool for etching amorphous carbon films.

Phase shifter based on two-dimensional electron system on a dielectric substrate

We experimentally investigate phase shift gained by electromagnetic radiation transmitted through a two-dimensional electron system (2DES) on a dielectric substrate. We systematically examined the dependence of the phase shift on the radiation frequency and 2DES electron density for the GaAs semiconductor substrate. A theoretical approach was developed that found good agreement with experimental results. We demonstrate a practically achievable phase shift of 105°. Obtained findings pave the way for the design of terahertz devices that can manipulate the radiation phase in a controlled and precise manner.

The effect of pressure on the thermodynamic properties of hydrogenic impurity in the GaAs semiconductor quantum well

ABSTRACT Studying the thermodynamic properties of hydrogen impurity in low-dimensional nanostructures under high-pressure environment is crucial for understanding the optical property and thermal excitation behaviour of semiconductor material. Here, we extensively explore the effect of pressure on thermodynamic properties, specifically, the average energy, free energy, entropy, and heat capacity of one-dimensional (1-D) hydrogenic impurity in GaAs semiconductor quantum well. Our findings reveal some novel phenomenon in the thermodynamic properties of hydrogenic impurity as pressure increases in the GaAs quantum well. Remarkably, at a constant temperature, both the average energy and free energy of hydrogenic impurity decrease as pressure rises, while entropy increases with increasing pressure. Intriguingly, the heat capacity shows distinct behaviour with varying pressure for different sizes of the quantum well. For very small size of the quantum well, the heat capacity increases with increasing pressure. However, for larger size of the quantum wells, the variation of heat capacity with pressure becomes irregular, showing a changeover from an increase to a decrease in response to increasing pressure. This research presents a pioneering method that employs pressure as a versatile tool for modulating the thermodynamic properties of hydrogenic impurity states in the nanostructures, and has some guidance for the preparation and synthesis of semiconductor devices.

Systematic study of FIB-induced damage for the high-quality TEM sample preparation

Nowadays, a focused Ga ion beam (FIB) with a scanning electron microscopy (SEM) system has been widely used to prepare the thin-foil sample for transmission electron microscopy (TEM) or scanning TEM (STEM) observation. An establishment of a solid strategy for a reproducible high-quality sample preparation process is essential to carry out high-quality (S)TEM analysis. In this work, the FIB damages introduced by Ga+ beam were investigated both experimentally and stopping and range of ions in matter (SRIM) simulation for silicon (Si), gallium nitride (GaN), indium phosphide (InP), and gallium arsenide (GaAs) semiconductors. It has been revealed that experimental investigations of the FIB-induced damage are in good agreement with SRIM simulation by defining the damage as not only “amorphization” but also “crystal distortion”. The systematic evaluation of FIB damages shown in this paper should be indispensable guidance for reliable (S)TEM sample preparation.

Nonlinear optical response of strain-mediated gallium arsenide microwire in the near-infrared region.

Gallium arsenide (GaAs) semiconductor wires have emerged as potent candidates for nonlinear optical devices, necessitating bandgap engineering for an expanded operational wavelength range. We report the successful growth of strain-mediated GaAs microwires (MWs) with an average diameter of 1.1 μm. The axial tensile strain in these wires, as measured by X-ray diffraction and Raman scattering, ranges from 1.61 % to 1.95 % and from 1.44 % to 2.03 %, respectively. This strain condition significantly reduces the bandgap of GaAs MWs compared to bulk GaAs, enabling a response wavelength extension up to 1.1 μm. Open aperture Z-scan measurements reveal a nonlinear absorption coefficient of -15.9 cm/MW and a third-order magnetic susceptibility of -2.8×10-8 esu at 800 nm for these MWs. I-scan measurements further show that the GaAs saturable absorber has a modulation depth of 7.9 % and a nonsaturation loss of 3.3 % at 1050 nm. In laser applications, GaAs MWs have been effectively used as saturable absorbers for achieving Q-switched and dual-wavelength synchronous mode-locking operations in Yb-bulk lasers. These results not only offer new insights into the use of large diameter semiconductor wires but also expand the potential for applications requiring bandgap tuning.

Dimensional quantization in InSb and GaAs in three-zone model

Various cases of size quantization in narrow-gap crystals of cubic or tetrahedral symmetry in the three-band Kane approximation are analyzed. Expressions for the energy spectrum depending on the two-dimensional wave vector are obtained for two different cases, differing in the range of current carrier energy values. The size-quantized energy spectrum of electrons in the conduction band and holes in the subband of light holes in InSb and GaAs semiconductors is analyzed in the three-band Kane model.

Combined effects of temperature and confinement on the Shannon entropy of two-dimensional hydrogenic impurity states in the GaAs semiconductor quantum well

Understanding the quantum properties of two-dimensional (2-D) hydrogenic impurity states in the GaAs quantum well is essential for their applications in the semiconductor devices. Here, we report the combined effects of temperature and quantum confienment on the Shannon entropy of 2-D hydrogenic impurity states in the GaAs quantum well. First, by calculating the position and momentum space Shannon entropy (Sr and Sp), as well as the Shannon entropy sum (St), for the hydrogenic impurity states in the GaAs quantum well at room temperature, we show fascinating quantum confinement properties in the two conjugated spaces. Then, the effects of temperature on the Shannon entropy for different hydrogenic impurity states are examined and compared. Intriguingly, we discover that the Shannon entropy sum exhibits the property of translation invariance under the influence of temperature. Finally, with the radius of the quantum well fixed at a constant, we observe that the value of the Shannon entropy for a given quantum state is highly sensitive to the variations in temperature. While the size of circular quantum well is constrained by design parameters, such as the fabrication process and intended application, temperature adjustment emerges as a viable means to control the quantum properties of 2-D hydrogenic impurities in the quantum well. This research presents a pioneering method that employs temperature as a versatile tool for modulating the Shannon entropy of hydrogenic impurity states in the quantum well, and has potential applications in the field of semiconductor physics, material physics, chemical physics, etc.

To the Theory of Dimensional Quantization in Narrow-Gap Crystals

This article discusses studies of size quantization phenomena in zero-, one-, and two-dimensional semiconductor structures. The main attention is paid to the mechanisms of photon-kinetic effects in these structures. Despite many studies of the physical properties of low-dimensional systems of current carriers, the size quantization of energy spectra in narrow-gap semiconductors and the associated photonic-kinetic effects are still insufficiently studied. Therefore, this study focuses on the quantum mechanical study of size quantization in certain cases using Kane's multiband model. The insolvability of the 8×8 matrix Schrödinger equation in the Kane model for a potential well of arbitrary shape is analyzed. The dependence of the energy spectrum on the two-dimensional wave vector is studied for various cases. In particular, the energy spectra for InSb and GaAs semiconductors are considered, depending on the band parameters and the size of the potential well. Conclusions are presented on the analysis of various cases of size quantization in narrow-gap crystals with cubic or tetrahedral symmetry in the three-band approximation. It is shown that the energy spectrum corresponds to a set of size-quantized levels that depend on the Rabi parameter, band gap, and well size. The size-quantized energy spectra of electrons and holes in InSb and GaAs semiconductors are analyzed in a multiband model.

Facile Synthesis and the Thermal Properties of Al/Si Composites Prepared via Fast Hot-Pressing Sintering

In this paper, a novel power sintering technique, named fast hot-pressing sintering (FHP), which is able to achieve an ultrahigh heating rate similar to the spark plasma sintering (SPS) technique, but at a much lower cost, was applied to prepare a series of Al/Si composites with different Si volume ratios (12 vol.% to 70 vol.%) to meet the requirements of advanced packaging materials for electronic devices. In contrast to SPS, the FHP oven possesses a safe and budget-friendly current power supply, rather than a complex and expensive pulse power supply, for its heating power. The optimized sintering parameters (temperature, pressure and holding time) of FHP for preparing Al/Si composites were investigated and determined as 470 °C, 300 MPa and 5 min, respectively. In order to characterize the potential of Al/Si composites as packaging materials, thermal conductivities and coefficients of thermal expansion were studied. The thermal conductivity of the Al-40Si composite sintered by the FHP method is higher than that of the conventional SPS method (139 to 107 W m−1 K−1). With the increase in Si, the thermal conductivities and coefficients of thermal expansion on both decreases. Furthermore, the thermal conductivities obey the Agari model, whereas the coefficient of thermal expansion and Si volume ratios obey additivity. The numeric modeling would help develop required packaging materials based on the thermal performances of the substrate materials, like Si or GaAs semiconductor devices.

Effects of electric field and device size on the electron velocity in p-i-n GaAs semiconductor

This paper introduces the investigation of the influence of electric field and device size on the drift velocity of electrons in GaAs semiconductor using ensemble Monte Carlo simulation method under limited size conditions. We employed a GaAs diode device model with p-i-n structure, consisting of p-type and n-type semiconductor layers with uniform size of 20 nm, and a variable-sized intrinsic (i) semiconductor layer in between. We show that in the absence of external electric field, the damped velocity will diminish as the size of the (i) layer ranges from 100 nm to 800 nm. And the damped oscillation period of the electron velocity is a linear function of the device size. Additionally, by examining the maximum value of electron velocity under the influence of an external electric field, our observed results are consistent with those reported by Saraniti et al. (2002) [22] in low electric field below 50 kV/cm; while at higher electric fields, the maximum velocity gradually increased to a saturation value. Furthermore, the maximum velocity vmax is found to follow a simple logarithmic law as a function of i-layer size S as vmax=aln⁡(bS). The coefficients of this relation equation were derived using least-square approximation technique yielding a high determination coefficient R2 up to 0.998.

Optical fractal in cryogenic environments based on distributed feedback Bragg photonic crystals.

We studied the optical fractal effect of the one-dimensional distributed feedback Bragg photonic crystals formed by semiconductor GaAs and dielectric TiO2. Light wave is transmitted in the intermediate dielectric slab and reflected back by the periodic photonic crystals at both ends, forming multiple fractal resonance output. The transmission channels expand exponentially by thickening the bulk in a cryogenic environment. The quality factor of each fractal resonant state improves with a greater periodic number of crystals. Furthermore, central wave of resonance has a blue-shift as the external pressure increases, while the influence of environment temperature on the fractal resonance could be ignored. It is hoped that our study can highlight the potential of these findings for designing multi-channel communication filters in cryogenic environments.