Kinetics study of initial stage band bending at metal GaAs(110) interfaces

Abstract

A systematic kinetics study of the initial stage band bending of metal/GaAs(110) has been done. At low temperature, independent of metals, enhanced band bending for p-GaAs and attenuated band bending for n-GaAs as a function of metal coverage has been observed. For p-type GaAs the band bending increases very rapidly to a value larger than that for any coverage at room temperature and then returns to the room temperature position at high coverages. It is found that this excess band bending strongly depends on the work functions of the metal deposited on GaAs. In gives 0.4 eV, Al 0.3 eV, Ag 0.2 eV, and Au only shows small excess band bending. Temperature dependence of GaAs initial stage band bending will also be discussed in this paper. The results strongly suggest that there exists another mechanism which appears to be dominant in the initial stage band bending at low temperature where the defect formation is negligible. The transition from this mechanism to the defect mechanism could be observed by increasing either system temperature or metal coverage, or more generally, disturbance to semiconductor surfaces.