Magnetotransport studies of high-mobility metamorphic heterostructures containing InxGax -1As quantum well (QW) with a high InAs content (x >= 0.85) have been carried out. The scattering rate can be effectively controlled by adjusting the spacer thickness between the QW and the delta-doping layer. By analyzing the temperature and angle dependences of the Shubnikov-de Haas oscillations, the effective mass m(& lowast;) , the quantum lifetime tau(q) , the effective g(& lowast;) -factor, and the nature of the scattering potential were determined. Estimates were also carried out within the framework of the kp Kane model, which confirm a significant manifestation of nonparabolicity in the measured values of m(& lowast;).

Photoconductive antennas based on low-temperature gallium arsenide (LT-GaAs) with a gold plasmonic-gold grating made of nanorods and nanoislands have been developed and fabricated. The antennas were produced using molecular beam epitaxy and electron-beam nanolithography. LT-GaAs samples with a high annealing temperature of 943 K were employed in the fabrication process. It has been demonstrated that plasmonic nanostructures significantly enhance the efficiency of light-to-terahertz radiation conversion by photoconductive antennas.

The paper presents experimental results of the appearance of a voltage at the potential contacts in the absence of an external current through a sample in the plateau region of the quantum Hall effect in a heterostructure with an InGaAs/InAlAs quantum well. The occurrence of a voltage is associated with the nonequivalence of the edge current in the potential contact areas in a magnetic field in a system with a two-dimensional electron gas.

Oxides and their heterostructures exhibit a plethora of functional properties with a potential for new device concepts. That makes the basis for oxide electronics which, however, stands aside from the currently dominant semiconductor electronics. To bridge the gap between oxide electronics and mainstream technologies, integration of oxides with the ubiquitous semiconductor platforms is necessary but highly challenging. An issue of a particular current interest is synthesis of magnetic oxide/semicnductor structures for applications in semiconductor spintronics. Here, we solve the long-standing problem of direct epitaxial integration of the paradigmatic ferromagnetic semiconductor EuO with GaAs, a workhorse of the modern electronics. We probe different synthetic routes, ranging from low-temperature tuning of reactant fluxes to high-temperature Eu distillation, explore protection of the GaAs surface by a Eu reconstruction. Weak distillation is established as the optimal synthesis route irrespective of the surface protection. The engineering of a direct contact between EuO and GaAs marks a significant progress over previous works employing buffer layers at the interface. It provides an opportunity for spin injection into GaAs within an all-semiconductor structure. More generally, the study makes a platform for direct epitaxial integration of functional oxides with GaAs.

n Erratum to this paper has been published: https://doi.org/10.1134/S1063739723900043

Silicon doped indium arsenide polycrystalline thin films grown on c-oriented alpha-sapphire substrates by molecular beam epitaxy are explored. Structural and transport properties of the films are reported, with electron mobility of similar to 600 cm(2)/VGreek ano teleias achieved at room temperature and excellent temperature stability of electrophysical properties in the range of 80-320 K. It is found that the use of the InAlAs seed layer at the initial stage of growth leads to a decrease in the roughness of the n-InAs films and a decrease in the width of the X-ray rocking curves. This demonstrates the potential for realization of InAs-based temperature stable Hall effect magnetic field sensors.

This paper studies the design of a nonlinear model of AlGaAs/InGaAs/GaAs рHEMT microwave-frequency range transistors with a gate length of 0.15 µm using parametric analysis methods. In the calculations, not only nonlinear current sources but also the dependences of the nonlinear gate-source and gate-drain capacitances on voltages are studied. It is shown that the proposed model makes it possible to describe the IV characteristics of the studied device adequately in the range of drain currents from 0 to 100 mA and the frequency range from 5 to 45 GHz. The error of the model does not exceed 3%.

The study represents the light and current parameters of an InGaAs/AlGaAs/GaAs double heterostructure, the layers of which were simultaneously subjected to doping and intermixing by rapid thermal annealing of zinc from a metal layer with a SiO2 coating at different temperatures and firing times: 1) 700 °C, 5 min; 2) 650 °C, 5 min; 3) 650 °C, 15 min. A comparison of samples with different temperatures and times of zinc annealing showed that an increase in the time and temperature of the process increases the shift of the luminescence maximum peak to the short-wavelength region. The best shift was 87 nm.

An algorithm for solving exciton Schrodinger equation in an arbitrary 2D multiple quantum well structure under applied electric field is proposed, allowing one to model both the absorption and refraction spectra consistently and efficiently. It gives much better quantitative results than variational approximation, while being faster than more advanced methods. The algorithm is implemented using R language and tested by comparing to other published results. Possible improvements are discussed.

A new structure for photoconductive antennas is proposed, which represents a multilayer epitaxial film grown on a GaAs(111)A substrate and consisting of alternating low-temperature grown undoped GaAs (LTG-GaAs) layers and GaAs layers formed in the standard high-temperature mode and doped with silicon (GaAs:Si). The As4 and Ga flow ratio γ is chosen such that the GaAs:Si layers have p-type conductivity. The LTG-GaAs layers are grown at a high γ value. A similar structure is grown on a (100) substrate as a reference. The structural properties of the samples are investigated: the phase composition is explored by high-resolution X-ray diffractometry; the surface relief, by atomic-force microscopy, and the Si-impurity thickness distribution, by secondary-ion mass spectrometry.

The design of a terahertz (THz) quantum cascade laser (QCL) with an active module based on three GaAs/Al0.18Ga0.82As quantum wells for high-temperature generation at a frequency of about 3.3 THz is optimized. A heterostructure based on the developed design with an active region thickness of 10 μm is grown by molecular-beam epitaxy with a deviation of the active-module thickness from the nominal of less than 1%. The fabricated THz QCLs with a double metal waveguide demonstrate lasing up to a temperature of 125 K. Investigations of the I–V characteristics, the dependences of the integrated emission on the current, and the lasing spectra show good agreement with the calculated characteristics.

The effect of 5 min high-temperature thermal annealing on InGaAs/GaAs strained superlattices and InGaAs/ AlGaAs PHEMT structures grown by molecular beam epitaxy was studied using the Hall measurements, pho-toluminescence spectroscopy, and high-resolution X-ray diffraction. InGaAs/GaAs superlattices are shown to undergo photoluminescence peak energy blueshift after 700 degrees C annealing and distinguishable heterointerface roughening after 800 degrees C annealing. The magnitude of quantum well smoothing, caused by annealing induced III-group atom interdiffusion, was estimated experimentally using secondary ion mass spectrometry and X-ray reflectivity, and calculated from the modelled electron energy spectra in the diffused wells. InGaAs/AlGaAs PHEMTs appear to be more sensitive to annealing, demonstrating optical and structural changes of a similar nature to InGaAs/GaAs heterostructures, as well as transport properties degradation, at a wider range of annealing temperatures starting 500 degrees C.

Semiconductor quantum dots (QDs) are known for their high capacity to nonlinear interaction with light via two-photon absorption (TPA). This allows them to absorb efficiently the infrared photons with energies lower than the bandgap energy. In addition, the TPA can be further enhanced due to interaction of QD excitons with plasmons of metal nanoparticles making it possible to design highly efficient optoelectronic devices with a nonlinear response to irradiation. To achieve this goal, we have fabricated the nonlinear photodetectors based on the QDs and silver nanoplates (SNPs) which combine both mentioned effects and demonstrate a highly efficient nonlinear photocurrent response at the excitation in the nearinfrared region of optical spectrum. In this study, we compared the photodetectors efficiency enhancement in hybrid devices based on the CdSe QDs and SNPs designed by the different ways. In one case, the SNPs were deposited on the top of 10 layers of QDs, and in the other, they were placed between these layers. We have demonstrated that both types of hybrid photodetectors operate in the two-photon regime. At the same time, we have found that the two-photon absorption efficiency was significantly higher in the sample where the SNPs were located between the QD-layers.

A highly accurate method for modeling InAlAs/InGaAs MHEMT transistors of the UHF frequency range with a gate length of 0.15 μm is considered. This method takes into account the nonlinear dependences of the internal parameters on the applied voltages. It is established that the maximal error of modeling is not larger than 1.5

A new lasing scheme with sequential two-photon emission in the gain module for terahertz quantum cascade laser (THz QCL) is proposed and experimentally demonstrated. THz QCLs based on MBE- and MOCVD-grown structures with two-photon design have a lasing frequency of 3.8 THz and maximum operation temperature around 100 K.

In this work, we have optimized the THz QCL design with an active module based on three GaAs/Al0.18Ga0.82As quantum wells for high-temperature generation at a frequency of about 3.3 THz. A heterostructure based on the developed design with an active region thickness of 10 μm was grown by molecular beam epitaxy with a deviation of the active module thickness from the nominal less than 1%. The fabricated THz QCLs with a double metal waveguide demonstrate lasing up to a temperature of 125 K. Investigations of the I–V characteristics, the dependences of the integrated radiation on the current and the lasing spectra showed good agreement with the calculated characteristics.

This work presents a process design kit (PDK) for a 0.15 μm GaAs pHEMT process for low-noise MMIC applications developed for AWR Microwave Office (MWO). A complete set of basic elements is proposed, such as TaN thin film resistors and mesa-resistors, capacitors, inductors, and transistors. The developed PDK can be used in technology transfer or education.