[1] [1] Janowitz C, Scherer V, Mohamed M, et al. Experimental electronic structure of In2O3 and Ga2O3［J］.New Journal of Physics,2011,13(8): 1-15.

[2] [2] Takakura K, Koga D, Ohyama H, et al. Evaluation of the crystalline quality of β-Ga2O3 films by optical absorption measurements［J］.Physica B Condensed Matter,2009,404(23-24): 4854-4857.

[7] [7] Laugier M T. Indentation cracking in ceramics and cermets［J］.Proceedings of the 2nd international conference on science of hard materials,1986: 449-455.

[10] [10] Zhang T H, Feng Y H, Yang R, et al. A method to determine fracture toughness using cube-corner indentation［J］.Scripta Materialia,2010,62(4): 199-201.

[11] [11] Yang R, Zhang T H, Jiang P, et al. Experimental verification and theoretical analysis of the relationships between hardness, elastic modulus, and the work of indentation［J］.Applied Physics Letters,2008,92: 1-4.

[12] [12] Yang R, Zhang T H, Feng Y H. Theoretical analysis of the relationships between hardness, elastic modulus, and the work of indentation for work-hardening materials［J］.Journal of Materials Research,2010,25(11): 2072-2077.

[13] [13] Johnson K L. Contact mechanics［D］.Cambridge: Cambridge University Press,1985.