Affiliation:
1. Japan Fine Ceramics Center 1 , 2-4-1 Mutsuno, Atsuta, Nagoya 456-8587, Japan
2. Novel Crystal Technology, Inc. 2 , Sayama 350-1328, Japan
Abstract
Load-dependent and angle-dependent nanoindentation tests were performed on a (2¯01)-oriented single-crystal β-Ga2O3 substrate to study the mechanical properties of the material. The anisotropy of the mechanical properties was examined, especially with regard to the dependence of the elastic modulus (E), hardness (H), and form of plastic deformation on the rotation angle of a Berkovich indenter with respect to the monoclinic structure. E reached a maximum value and H a minimum value when the sample was rotated to such an angle that one of the three facets of the Berkovich indenter was parallel to the [010] direction. To compare our experimental results with the theoretical calculation based on the monoclinic structure, the elastic surface of β-Ga2O3 was calculated using fourth-rank stiffness and compliance tensors and visualized in three-dimensional space. Two-dimensional sectional maps of the elastic surface were obtained for a range of crystal planes, and good agreement was obtained between the experimental observations and calculations. Plastic deformation at the indenter impressions was evaluated using scanning and transmission electron microscopy, and dislocations, cleavage, and cracks were observed. Their structure and density depended on the rotation angle. Our results clearly show a strong anisotropy of the mechanical properties of β-Ga2O3, which is very different from what is found in other compound semiconductors for power-device applications, such as GaN and 4H-SiC. This emphasizes the importance of customizing the machining process for β-Ga2O3, rather than simply using “machining recipes” for other materials.
Funder
Innovative Science and Technology Initiative for Security
Japan Society for the Promotion of Science
Murata Science Foundation
Nippon Sheet Glass Foundation for Materials Science and Engineering
Kazuchika Okura Memorial Foundation
Sumitomo Foundation
Kurata Memorial Hitachi Science and Technology Foundation
Iketani Science and Technology Foundation
Subject
General Physics and Astronomy
Cited by
3 articles.
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