The features of resistive switching in memristors based on crystalline aluminum nitride with a wurtzite structure, grown under technology developed at the National Research Center “Kurchatov Institute” are studied.

The physical characteristics of a two-dimensional electron gas located in the GaN layer near the AlN/GaN interface of AlGaN/AlN/GaN heterostructures have been studied for decades. According to the currently accepted concepts, its symmetry coincides with that of the nonsymmorphic space group C \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{{6{v}}}<^>{4}$$\end{document} in the bulk of GaN. However, this is incorrect. Indeed, the only nonsymmorphic element of this group-the rotation of the system about the [0001] axis normal to the interface plane, with a simultaneous shift along this axis by half a period of the GaN crystal lattice-is forbidden for a two-dimensional gas owing to the confinement potential, which, therefore, reduces its symmetry to the symmetry of the trigonal point group C \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{{3{v}}}$$\end{document} . This fact has been confirmed in this work by ab initio density functional calculations and by electrophysical data.

— Microwave transistors based on AlN/GaN heterostructures on silicon substrates are fabricated and studied. The maximum specific saturation current is more than 1 A/mm and the transconductance is 444 mS/mm. Current gain cut-off frequency f t and maximum oscillation frequency f max are 124 and 161 GHz, respectively. The power gain is 13.7 dB at 30 GHz.

In this work, thermometric measurements of gallium nitride-based ungated transistors on silicon-on-diamond composite substrates are performed. Their heat sink efficiency is compared with transistors made by standard technology on a silicon carbide substrates. Reducing of the surface temperature by more than 50°C using new type of silicon-on-diamond composite substrates at dissipation power above 7 W is shown. The proposed approach is promising for increasing the output power and reliability of gallium nitride-based devices.

A new approach to the fabrication of efficient heat sinks for GaN-based transistors is demonstrated. A key feature of this work is the growth of polycrystalline diamond coating on the functional silicon layer of SOI wafers followed by etching of a thick silicon substrate and a thin thermal oxide. As a result, composite epi-ready substrates consisting of a thin (410 nm) monocrystalline silicon functional layer on top of the 150 mu m-thick polycrystalline diamond heat sink were fabricated. GaN heterostructures were grown on top of the silicon layer, which resulted in an effective thermal contact between CVD diamond and GaN structure. The packaged ungated transistors were made to analyze the efficiency of the developed heat sink. Improved heat removal structures showed the decrease in surface temperature by more than 50 degrees C at base temperature of T-b =85 degrees C and dissipation power of P-d(i)ss=6.9 W/mm compared to conventional GaN-on-SiC technology and by more than 20 degrees C at T-b=25 degrees C, P-diss=6.9 W/mm compared to up-to-date GaN-on-Diamond equivalent transistors reported by other groups. New substrate fabrication technology positively impacts GaN-based device output characteristics and reliability, which is important in improving communication systems, radars, and secondary power supply systems. (C) 2021 The Authors. Published by Elsevier Ltd.

In this work, thermometric measurements of gallium nitride-based ungated transistors on silicon-on-diamond composite substrates are performed. Their heat sink efficiency is compared with transistors made by standard technology on a silicon carbide substrates. Reducing of the surface temperature by more than 50oC using new type of silicon-on-diamond composite substrates at dissipation power above 7 W is shown. The proposed approach is promising for increasing the output power and reliability of gallium nitride-based devices. Keywords: gallium nitride, heat sink, diamond, dissipation power.

Silicon wafers with a polycrystalline diamond heat sink have been fabricated; the silicon and diamond layers have thicknesses of 234 nm and 250 μm, respectively. The diamond thermal conductivity is 1290 ± 190 W/(m K). Nitride heterostructures with two-dimensional electron gas have been grown on silicon substrates with a polycrystalline diamond heat sink using ammoniacal molecular-beam epitaxy. The electron mobility in the two-dimensional electron gas and its sheet resistance are 1600 cm2/(V s) and 300 Ω/□, respectively.

Silicon wafers with a polycrystalline diamond heat sink were fabricated; silicon and diamond layers were 300 nm and 250 µm thick, respectively. The thermal conductivity of the diamond was 1290 ± 190 W / m • K. Nitride heterostructures with a two-dimensional electron gas on silicon substrates with a polycrystalline diamond heat sink were grown by ammonia molecular beam epitaxy. Carrier mobility in two-dimensional electron gas and sheet resistance were 1400 cm2 /V•s of 300 Ω/□, respectively.

A new type of substrates for the growth of nitride heterostructures is presented that consists of a 125-nm thick silicon layer and 290-μm thick polycrystalline diamond. The possibility of epitaxial growth of nitride heterostructures on silicon–polycrystalline diamond substrates with characteristics at the level of heterostructures on silicon substrates is shown. The test transistors demonstrated the following: saturation current density of more than 1 A/mm and breakdown voltage of more than 90 V. The achieved results open up opportunities for the emergence of a new class of silicon-polycrystalline diamond substrates and the creation of powerful gallium nitride transistors with previously unattainable characteristics.

In this study, nitride heterostructures were grown on silicon substrates by metalorganic chemical vapour deposition. Transistors with a 1.32-mm periphery were fabricated based on them. The saturation power of transistors at a frequency of 1 GHz amounted to 4 W and 6.3 W at a supply voltage of 30 V and 60 V, respectively. The maximum drain efficiency was 57%.

Предложен и реализован уникальный метод формирования гетероструктур на основе нитрида галлия на подложках кремния при пониженных температурах роста (менее 950°С). Сформированная гетероструктура обладает атомарно-гладкой поверхностью со средней квадратичной шероховатостью 0.45 нм и высоким кристаллическим качеством. Среднее слоевое сопротивление канала двумерного электронного газа составило 415 Ом/квадрат при концентрации электронов 1.65 · 1013 см–2 и подвижности 920 см2 /В · с. Максимальная величина тока насыщения стока для транзисторов с шириной затвора 1.2 мм составила 930 мА/мм, что соответствует лучшим мировым результатам для нитрид-галлиевых транзисторов на подложках кремния.

GaN heterostructures on silicon substrates have been grown by metalorganic chemical vapor deposition. Transistors with the gate periphery of 1.32 mm are designed. The saturation power of the package die at a frequency of 1 GHz was 4 and 6.3 W at supply voltages of 30 and 60 V, respectively. The maximum drain efficiency is 57%.

Gallium nitride heterostructures on silicon substrates were grown by the method of gas-phase epitaxy from organometallic compounds. Based on them, transistors with a total gate width of 7.92 mm were created. The influence of the architecture of buffer layers on the characteristics of heterostructures and test transistors based on them is studied. Powerful transistors were obtained with an output pulse power of 45 W at a frequency of 1 GHz with a supply voltage of 28 V. The maximum efficiency of the transistor was 55%.