Current switches based on low-voltage InP heterothyristors with a maximum blocking voltage of 20V were developed and studied. In current pulse generation mode, the efficient operation of InP heterothyristors with a low-resistance load in the form of a capacitor was demonstrated. It has been shown that the minimum turn-on delay time is about 6 ns at a control current amplitude of 60 mA. The possibility of generating current pulses with a duration of 53–154 ns and amplitudes of 38–130 A was demonstrated when the capacitor values were changed in the range of 56–1000nF.

We have demonstrated a quantum cascade laser (QCL) with a generation frequency of about 3.8 THz, grown by metal-organic vapor phase epitaxy. The multilayer heterostructure for QCLs consists of 185 repetitions of an active module containing four GaAs/Al0.15Ga0.85As quantum wells. The threshold current and threshold voltage of the fabricated QCL were 2.25 kA/cm2 and 19.7 V, respectively. The QCL was generated in the multimode regime, and the detection of terahertz radiation continued with an increase in the laser temperature up to 60 K.

The possibility of fabrication of 4.6 µm spectral range quantum-cascade laser heterostructures by molecular-beam epitaxy technique with non-selective overgrowth by the metalorganic vapour-phase epitaxy is shown. The active region of the laser was formed on the basis of a heteropair of In0.67Ga0.33As/In0.36Al0.64As solid alloys. The waveguide claddings are formed by indium phosphide. The results of surface defects inspection and X-ray diffraction analysis of quantum-cascade laser heterostructures allow to conclude that the structural quality of the heterostructures is high and the estimated value of the root mean square surface roughness does not exceed 0.7 nm. Lasers with four cleaved facets exhibit lasing at room temperature with a relatively low threshold current density of the order of 1 kA /cm2.

Исследованы выходные характеристики мощных одночастотных лазеров с распределенной обратной связью с боковой брэгговской дифракционной решеткой. Приведены рекордные значения энергетических и спектральных характеристик одночастотных РОС-лазеров.

The switching on process spatial dynamics of a laser-thyristor based on an AlGaAs/InGaAs/GaAs heterostructure with a thin p-base has been studied. The heterostructure had a modified base with a middle-doped layer at the n-emitter, which makes it possible to increase the operating voltages in order to generate nanosecond current pulses. In laser thyristor pulsed sources based on the proposed heterostructure, a high degree of current flow region localization arising during turn on process of the device was demonstrated. Using the current localization regions luminescence, the propagation dynamics of the switched-on state was estimated. The anode contact sizes required for the nanosecond range pulsed current switches or laser emitters development are obtained.

Abstract The internal electric fields of InGaN/GaN-based green-emission LED heterostructures with various numbers of quantum wells in the active region are investigated by electrotransmission spectroscopy. The frequencies of the observed spectral lines are attributed to possible types of interband transitions. An increase in the number of interband transitions of the “quantum well—quantum barrier” type with an increase in the number of quantum wells is found. This is explained by the nonidentical degree of segregation of In atoms in different GaN barriers layers. The strength of internal electric fields in quantum wells is calculated for various values of the bias of the p – n junction using a series of electrotransmission spectra. It is found that the strength of the internal piezoelectric field decreases from 3.20 to 2.82 MV/cm with an increase in the number of quantum wells.

Abstract InGaN/GaN-based LED heterostructures with different numbers of quantum wells are investigated by photocurrent spectroscopy in the wavelength range of 350–500 nm. As a result of the analysis of a series of spectra obtained at various p – n -junction biases, the effect of changing photocurrent direction when varying the excitation wavelength (photoreversible effect) is discovered. The range of p – n -junction biases for which this effect is observed in structures with different numbers of quantum wells in the active region is established.

A technique is proposed for determining the spatio-temporal dynamics of current in semiconductor heterostructures. This technique is based on the modulation of external radiation during passage through the crystal under study. Approbation of the technique was carried out on semiconductor laser-thyristor based on AlGaAs/ InGaAs/GaAs heterostructures. The experimental results are in a good qualitative agreement with previous measurements of the spatio-temporal dynamics in the laser-thyristor.

Выполнены расчеты составов эпитаксиальных слоев, формирующих низкоразмерные гетероструктуры Al x Ga y In 1-x-y As/InP для лазерных диодов с длиной волны излучения 1.55 мкм.При проведении расчетов ставилась задача обеспечения максимальной высоты энергических барьеров для эффективного ограничения носителей заряда в квантовых ямах.Наряду с эффектом размерного квантования энергии свободных носителей заряда в разрешенных зонах, учитывалось влияние упругих напряжений в эпитаксиальных слоях на смещение краев энергетических зон.Показано, что для решения поставленных задач необходимо формирование гетероструктур с напряжениями упругого сжатия в квантовой яме и напряжениями упругого растяжения в барьерных слоях.Предложена структура, включающая барьерный слой Al 0.28 Ga 0.30 In 0.42 As толщиной 110 Å и квантовую яму Al 0.03 Ga 0.23 In 0.74 As в слое толщиной 55 Å со степенями рассогласования параметров кристаллической решетки с подложкой InP -0.8% и +1.4%, соответственно.По результатам расчетной оценки, указанные толщины эпитаксиальных слоев не превышают критических значений, способных привести к образованию дислокаций несоответствия на гетерограницах.

AbstractHybrid laser structures with AlGaInAs quantum wells are grown by metalorganic vapor phase epitaxy on Ge/Si(100) “virtual” substrates using GaAs and InP buffer layers. Stimulated emission is achieved under optical pumping of the prepared samples in the range of 1.3–1.5 μm at liquid-nitrogen temperature. The stimulated-emission threshold is 30–70 kW/cm^2.