Semiconductors最新文献

Abstract

We have studied superluminescent diodes with simplified design and active region based on 5 or 7 layers of InGaAs/GaAs quantum well-dots (QWDs). Emission peaks of the individual QWD layers are shifted with respect to each other by 15–35 nm to provide as wide as possible emission line in a superluminescent mode with central wavelength of about 1 μm without significant spectral dips. For superluminescent diodes with the active region based on 5 and 7 QWD layers, the maximal value of full width at half maximum of emission spectrum was 92 and 103 nm respectively.

Abstract

The results of comparative studies of the optical and structural properties of Hg_0.7Cd_0.3Te bulk crystals and epitaxial films grown by various methods are presented. The data of photoluminescence studies performed in the temperature range 4.2–300 K showed the similarity of the optical properties of different samples and indicated a significant disordering of the solid solution. According to X-ray diffraction data, however, the scale of the disordering was not directly related to the structural quality of the material. The prospects for using the material grown by various methods in optoelectronics applications are discussed.

Abstract

The article investigates the effect of rapid thermal annealing of ternary GaAs_1–xN_x/GaAs solid solutions on the distribution of nitrogen atoms in the crystal lattice. The samples are studied by photoluminescence spectroscopy and high-resolution X-ray diffractometry. Due to the size and electronegativity mismatch of nitrogen and arsenic atoms, nitrogen is incorporated unevenly into the GaAs crystal lattice. Options of the nitrogen atoms arrangement in the GaAs crystal lattice before and after rapid thermal annealing are shown.

Abstract

A simple method for obtaining SiO₂:Ag:Si and Ag:Si hybrid nanostructures is presented. High-temperature annealing of an Ag island film on the surface of c-Si makes it possible to preserve the plasmonic properties of Ag nanoparticles and protect them from external influences by coating them with a thermally grown layer of SiO₂. The calculation of the electric field strength distribution in the structure with embedded Ag nanoparticles in c-Si demonstrates the presence of intrinsic “hot spots” at the corners of the nanoparticles, which leads to a maximum enhancement factor (~10⁶) of Raman scattering. A numerical calculation of the dependence of the spectral position of a localized plasmon resonance on the geometry of structures can serve as a basis for their design in the future. Surface-enhanced Raman scattering showed reliable detection of the methyl orange from an aqueous solution at a concentration of <10^–5 M.

Abstract

A systematic study of a series of InGaAs/GaAs lasers in the 1–1.3 μm optical range based on quantum wells (2D), quantum dots (0D), and quantum well-dots of transitional (0D/2D) dimensionality is presented. In a wide range of pump currents, the dependences of the lasing wavelength on the layer gain constant, a parameter which allows comparing lasers with different types of active region and various waveguide designs, are measured and analyzed. It is shown that the maximum optical gain of the quantum well-dots is significantly higher, and the range of lasing rawavelengths achievable in edge-emitting lasers without external resonators is wider than in lasers based on quantum wells and quantum dots.

The effect of H₂, NH₃, CO and O₂ on the electrically conductive properties of In₂O₃ films grown by halide vapor phase epitaxy has been studied. In the temperature range of 200−550°C, In₂O₃ films demonstrate gas sensitivity to all considered gases, a relatively high operation speed and repeatability of cycles. The greatest response to NH₃ was obtained, which exceeded 33 arb. units at a temperature of 400°C and a gas concentration of 1000 ppm⁻¹. A qualitative mechanism of gas sensitivity of In₂O₃ films is proposed. The obtained gas-sensitive characteristics are compared with known In₂O₃ sensors based on various materials. It is shown that the method of halide vapor phase epitaxy makes it possible to obtain indium oxide films with high gas sensitivity.

Abstract

The results of theoretical and experimental studies of impact ionization processes and charge carrier heating in multi-valley A^IIIB^V semiconductors at high electric field are presented and their relationship with the features of the band structure is discussed. A role of subsidiary L- and X-valleys, complex structure of the valence band and orientation dependence of the ionization coefficients are taken into account. A new approach to the choice of semiconductor materials with a large ratio of the ionization coefficients of holes and electrons to create the noiseless avalanche photodiodes due to monopolarity of hot charge carrier multiplication is proposed.

Abstract

Utilizing performed research, photoelectric converters of narrow-band radiation (λ ≈ 1.0–1.3 μm) based on InGaAsP/InP heterostructures with an epitaxial p–n junction have been developed and created. Technological regimes that apply of for creating high-quality layers of quaternary InGaAsP solid solutions isoperiodic to indium phosphide in a wide range of compositions by liquid-phase epitaxy have been determined.

Abstract

In this work, we measured the correlator spectrum of optically cooled nuclear spin system of a bulk n-GaAs crystal in a zero magnetic field. The resulting spectrum is described by two contours, which can be interpreted as the participation of nuclear spins in two types of interactions. We analyzed the measured spectrum in the model for classical magnetic moments in the GaAs lattice. The analysis showed that the main contribution to the high-frequency part of the spectrum is due to the dipole-dipole interaction, and that to the low-frequency part is due to the quadrupole interaction.

Abstract

Three main reasons for a temperature increase in activated p-InAsSbP/n-InAs/n-InAsSbP and p-InAsSbP/n-InAsSb/n-InAs double heterostructures has been considered, contribution of nonradiative Auger recombination, electron-phonon interaction and Joule heating to diode temperature increase in single element LEDs and flip-chip diode arrays (1 × 3) were evaluated at forward and reverse bias using data on spatial distribution of the mid-IR radiation intensity and current-voltage characteristics.