В докладе показаны актуальные результаты разработки отечественной технологии выращивания гетероструктур на основе нитрида галлия (GaN) на сверхвысокоомных эпитаксиальных структурах кремния диаметром 150 мм. Получены структуры Ga(Al)N/Si диаметром до 150 мм с подвижностью электронов в 2DEG более 1500 см2В-1с-1, изготовлены тестовые транзисторы GaN HEMT с напряжением отсечки порядка -6,5 В, максимальным током стока насыщения 570 мА/мм, крутизной транзисторов не менее 100 мСм/мм и пробивным напряжением более 200 В.

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 temperature stability of Ge/Au/Ni/Au ohmic contacts to GaAs nanoheterostructures and Ti/Al/Ni/Au ohmic contacts to GaN nanoheterostructures on silicon substrate was investigated. It has been established that optimization of the RTA process made it possible to obtain ohmic contacts with field emission current flow mechanism. The thermal stability of ohmic contacts for transistors and mesa resistors demonstrated the threshold behavior of the heat treatment temperature. The optimum process parameters for temperature stability and minimum contact resistance were defined. Keywords: ohmic contact, gallium arsenide, gallium nitride.

This article demonstrates TCAD simulation of normally-off p-channel , n-channel transistors based on a p-GaN gate power platform and estimates interconnections between the key parameters of the heterostructure and device behavior, in other words the type of transistor. GaN platform with p-GaN layer has been developed. It will allow to form n-channel and p-channel, normally-on and normally-off transistors on the same wafer in the same technological cycle and to create GaN complementary pair.

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.

The temperature stability of Ge/Au/Ni/Au ohmic contacts to GaAs nanoheterostructures and Ti/Al/Ni/Au ohmic contacts to GaN nanoheterostructures on silicon substrate was investigated. It has been established that optimization of the RTA process made it possible to obtain ohmic contacts with field emission current flow mechanism. The thermal stability of ohmic contacts for transistors and mesa resistors demonstrated the threshold behavior of the heat treatment temperature. The optimum process parameters for temperature stability and minimum contact resistance were defined.

Conventional AlGaN/GaN transistors are depletion-mode devices. For most applications, the E -mode, where the channel current is zero at the zero gate voltage, should be implemented. The feasibility of the E -mode opens prospects for designing digital circuits and power devices. A new method for fabricating normally-off E -mode transistors, i.e., the use of p -GaAs layer under the gate, is considered. As a method for forming this layer, plasma-chemical removal of the p -GaN layer outside the gate is chosen. This gives rise to problems of an inhomogeneous etching depth and poor control of the etch rate. The heterostructure with an additional AlN barrier layer which is an etch stop layer is developed. The results of the study of the effect of various heterostructure parameters on the carrier concentration in the channel, and hence, on the transistor’s output characteristics, and the design process is developed. According to the latter, samples of normally-off transistors are fabricated, in which the maximum drain current in the on-state is 350 mA/mm at a gate voltage of 4 V, and the breakdown voltage is ~550 V in the off state at a gate voltage of 0 V.

This letter reports a nitrogen ion implantation through silicon nitride passivation layer deposited on AlGaN/GaN on Si heterojunction structure. Employment of Si3N4 layer simplify HEMT fabrication process and helps to obtain high resistivity isolation due to the shift of implanted ions distribution towards the surface of semiconductor. This isolation process in combination with C-doped heterostructure buffer layer results in increased up to 650 V breakdown voltage.

The electrophysical and photoluminescent characteristics as well as the surface morphology of GaAs epitaxial films grown by molecular beam epitaxy on GaAs (110) substrates are studied. Silicon-doped epitaxial layers were grown in a wide range of growth temperatures from 410 to 680 °C and a ratio of arsenic and gallium fluxes from 14 to 84. The ranges of growth conditions resulting in the smoothest epitaxial films surface were estimated by atomic force microscopy. The occurrence of point defects "a Si atom in a Ga site" and "a Si atom in a As site" as well as the formation of arsenic and gallium vacancies were interpreted by analyzing the photoluminescence spectra of the grown samples.

It is shown that intentionally undoped high-resistance GaN buffer layers in AlGaN/GaN heterostructures with high electron mobility for transistors can be formed by ammonia molecular beam epitaxy. The GaN growth conditions have been optimized using calculations of the background impurity and point defect concentrations at different ratios of the gallium and ammonia fluxes.

In this paper the possibility of obtaining the intentionally undoped high resistance GaN buffer layers in AlGaN/GaN heterostructures with high electron mobility for transistors by ammonia molecular beam epitaxy was demonstrated. The growth conditions based on background impurity concentrations and point defects calculations for different gallium and ammonia flows ratios were optimized.

AbstractThe active region of a THz (terahertz) quantum-cascade laser based on three tunnel-coupled GaAs/Al_0.15Ga_0.85As quantum wells with a resonance-phonon depopulation scheme is designed. Energy levels, matrix elements of dipole transitions, and gain spectra are calculated as functions of the applied electric-field strength F and temperature. It is shown that the maximum gain is implemented at a frequency of 3.37 THz and F = 12.3 kV/cm. Based on the proposed design, a quantum-cascade laser emitting at ~3.3 THz with a double metal waveguide and T _max ~ 84 K is fabricated. The activation energy E _ a = 23 meV for longitudinal-optical (LO) phonon emission upon the stimulated recombination of hot electrons from the upper laser level to the lower one is determined from the Arrhenius temperature dependence of the output power.

Исследованы зависимости положения электронных уровней и силы осциллятора переходов от приложенного электрического поля для терагерцового квантово-каскадного лазера (ТГц ККЛ)с резонансно-фононным дизайном на основе каскада, состоящего их трех квантовых ям. Рассчитаны напряженности электрического поля для двух характерных состояний исследуемого терагерцового квантово-каскадного лазера: 1) протекание паразитного" тока по структуре, когда порог генерации еще не достигнут; 2) порог генерации достигнут. Проведено моделирование процессов теплопереноса в исследуемых терагерцовых квантово-каскадных лазерах для определения оптимальных режимов питания и охлаждения. Подобраны режимы термокомпрессионного соединения гребневого полоска лазера с проводящей подложкой n+-GaAs на основе Au-Au для создания механически более прочного контакта c большей теплопроводностью. DOI: 10.21883/FTP.2017.04.44349.8414