An Investigation Of The Cause Of Initial Band Bending Of A Cleaved Clean n-GaAs(llO) Surface

Abstract

ABSTRACTThe cause of the initial band bending on a clean n-GaAs(llO) surface of so-called “poor quality cleavage” has been controversial. To study this problem, a new type of geometric factor multi-metal evaporator has been designed, which enables us to obtain reproducible metal coverages as low as 10−4 monolayers. By following the early stages of band bending induced by the deposition of noble metals Cu, Ag and Au on n-GaAs (110) surfaces of different cleavage quality, it is found that a certain amount of initial band bending of a clean GaAs(llO) surface of poor quality cleavage corresponds to a certain amount of noble metal coverage (usually lower than 0.01 ML). This phenomenon can be explained in the following way. Any initial band bending on a clean n-GaAs(HO) surface is due to surface defect states created by the cleaving. These cleavage induced defects may be of the same nature as the interface states created by deposited noble metal atoms. Our experimental results will be discussed in the framework of the unified defect model of the Schottky barrier formation on III-V semiconductors.