[1] Sheer J J, Laar V J. Solid State Commun, 1965, 3(8): 189.

[3] Yang Zhi, Chang Benkang, Zou Jijun, et al. Appl. Opt., 2007, 48(2): 7036.

[4] Gao H R. J. Sci. Tech., 1987, A5: 1295.

[5] Stocker B J. Sur. Sci., 1975, 47(6): 501.

[6] Burt M G, Heine V J. Soli. Stat. Phys., 1978, 11(3): 961.

[7] Clark M G. J. Appl. Phys., 1975, 8(1): 535.

[8] Aspnes D E. Phys. Rev., 1976, B14: 5331.

[9] Su C Y, Chye P W, Pianetta P. Sur. Sci., 1979, 86(9): 894.

[10] Su C Y, Lindau I, Spicer W E. Chem. Phys. Lett., 1982, 87(3): 523.

[11] Fisher D G, Enstrom R E, Escher J S. J. Appl. Phys., 1972, 43(5): 3815.

[12] Uebbing J J, James L W. J. Appl. Phys., 1970, 42(7): 5095.

[13] Gregory P E, Spicer W E, Ciraci S, et al. Appl. Phys. Lett., 1974, 25(2): 511.

[14] Cao R Y, Miyano K, Kendelewicz T, et al. Appl. Phys. Lett., 1989, 54(6): 1251.

[15] Sommer A H, Whitaker H H, Williams B B. Appl. Phys. Lett., 1970, 17: 273.