Michael Ray, Yves C. Martin
Proceedings of SPIE - The International Society for Optical Engineering
We report a photoreflectance study of Fermi level pinning (VF) on (001) n- and p-type GaAs with large, uniform electric fields. Surface photovoltage (Vs) effects were evaluated as a function of temperature (77 K< T<450 K), pump beam wavelength (633 and 407 nm) and W-metal coverage (in situ). The dependence of the measured barrier height, Vb(= VF — Vs),on T can be explained by a modification of the theory of M. Hecht [Phys. Rev. B 41, 7918 (1990)] yielding values of VF = 0.77 + 0.02 V and VF = 0.75 + 0.02 V for n- and p-type GaAs, respectively, at 300 K. In addition, by introducing the ratio (r) of the area of the surface states to the illuminated area into the theory of Hecht we have been able to estimate the density of surface states on the GaAs surface. The effect of metal coverage is to increase r and reduce the influence of Vs. © 1992 American Vacuum Society
Michael Ray, Yves C. Martin
Proceedings of SPIE - The International Society for Optical Engineering
Shu-Jen Han, Dharmendar Reddy, et al.
ACS Nano
Arvind Kumar, Jeffrey J. Welser, et al.
MRS Spring 2000
K.N. Tu
Materials Science and Engineering: A