Frontier Materials & TechnologiesFrontier Materials & TechnologiesFrontier Materials & Technologies2782-40392782-6074Togliatti State University17010.18323/2782-4039-2021-4-7-16ArticlesСтатьиThe study of mechanical deformation resistance of α-Ga2O3 epitaxial layers using the nanoindentation techniqueИсследование сопротивления механической деформации эпитаксиальных слоев α-Ga2O3 методом наноиндентированияhttps://orcid.org/0000-0003-4205-3226GuzilovaLyubov I.ГузиловаЛюбовь Игоревна
Russian Federation

acting junior researcher

исполняющий обязанности младшего научного сотрудника

luba-guzilova@yandex.ruhttps://orcid.org/0000-0002-4746-4238GrashchenkoAleksandr S.ГращенкоАлександр Сергеевич
Russian Federation

junior researcher

младший научный сотрудник

https://orcid.org/0000-0002-5630-0833NikolaevVladimir I.НиколаевВладимир Иванович
Russian Federation

PhD (Physics and Mathematics), Head of Laboratory, leading researcher

кандидат физико-математических наук, заведующий лабораторией, ведущий научный сотрудник

Ioffe Physical-Technical Institute of the Russian Academy of Sciences, St. Petersburg (Russia)Физико-технический институт им. А.Ф. Иоффе Российской академии наук, Санкт-Петербург (Россия)Institute of Problems of Mechanical Engineering of the Russian Academy of Sciences, St. Petersburg (Russia)Институт проблем машиноведения Российской академии наук, Санкт-Петербург (Россия)3012202147163012202130122021https://vektornaukitech.ru/jour/article/view/170

Gallium oxide (Ga2O3) is a wide-band semiconducting material with an energy gap width Eg=4.8–5.0 eV, high conductivity (λ~10.9–27.0 W/(m·K)), and radiation and chemical resistance. Its energy gap width and conductivity allow in the future using the material in the structures of power equipment and optoelectronic devices to increase their energy performance, i.e. to decrease heating and increase productive capacity. Radiation resistance, high breakdown field, and optical asymmetry of Ga2O3 make it attractive for application when designing UV-photoelectric receivers and space systems. The electrical and optical properties of Ga2O3 are amply studied, but there are no systematic data on its physical and mechanical properties (hardness, Young’s modulus, and crack resistance). The paper investigated the deformation in α-Ga2O3 epitaxial layers during nanoindentation. For indentation, the authors used NanoTest (Micro Materials Ltd.) hardness meter. The surface (0001) of α-Ga2O3 crystalline layers produced in the process of chloride gas epitaxy on sapphire (Al2O3) substrates with basic (0001) orientation was investigated. For the first time, the authors experimentally obtained the values of α-Ga2O3 hardness and Young’s modulus using the Oliver-Farr method. The dependences of the indentation load on the penetration depth demonstrated the deviation from linearity, including stress relaxation coming from the pop-in phenomenon. The average values of nanohardness H and Young’s modulus E were 17 and 281 GPa, respectively. The obtained H and E values demonstrate higher characteristics compared to the formerly studied β-Ga2O3 epitaxial layers. This discrepancy can be explained by the more close-packed arrangement of the α-Ga2O3 structure (the corundum type) than one of monoclinic β-Ga2O3. The study shows that α-Ga2O3 leaves the majority of semiconducting materials behind in its mechanical properties conceding only to gallium nitride (GaN) and sapphire (Al2O3).

Оксид галлия (Ga2O3) – широкозонный полупроводниковый материал, обладающий шириной запрещенной зоны Eg=4,8–5,0 эВ, высокой проводимостью (λ~10,9–27,0 Вт/(м·К)), радиационной и химической стойкостью. Ширина его запрещенной зоны и проводимость позволяют в перспективе использовать его в конструкциях силовых приборов и оптоэлектронных устройств, чтобы увеличить их энергоэффективность, т. е. уменьшить нагрев и увеличить производительность. Радиационная стойкость, высокое поле пробоя, асимметрия оптических свойств Ga2O3 делают перспективным его использование при проектировании УФ-фотоприемников и космической техники. Электрические и оптические свойства Ga2O3 изучены  достаточно полно, систематические же данные о его физико-механических свойствах (твердость, модуль Юнга, трещиностойкость) отсутствуют. В работе исследована деформация в эпитаксиальных слоях α-Ga2O3 при наноиндентировании. Для индентирования использовался твердомер NanoTest (Micro Materials Ltd.). Исследовалась поверхность (0001) кристаллических слоев α-Ga2O3, полученных в процессе хлоридной газовой эпитаксии на сапфировые (Al2O3) подложки базисной (0001) ориентации. Впервые экспериментально получены значения твердости и модуля Юнга α-Ga2O3 с использованием метода Оливера – Фарра. В зависимостях нагрузки на индентор от глубины его проникновения наблюдалось отклонение от линейного хода, в том числе релаксация напряжений, связанная с “pop-in” эффектом. Средние значения нанотвердости H и модуля Юнга E α-Ga2O3 составили 17 и 281 ГПа соответственно. Полученные значения H и E демонстрируют более высокие характеристики по сравнению с изученными ранее эпитаксиальными слоями β-Ga2O3. Это различие можно объяснить более плотной упаковкой структуры α-Ga2O3 (тип корунд), чем у моноклинного β-Ga2O3. Обнаружено, что α-Ga2O3 по своим механическим свойствам превосходит большинство полупроводниковых материалов, уступая лишь нитриду галлия (GaN) и сапфиру (Al2O3).

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