The Study of Silicon Diffusion into GaAs by Rapid Thermal Oxidation

Abstract

ABSTRACTThe diffusion of silicon into GaAs was investigated in this work. Shallow silicon carrier profile with doping levels in excess of 1018 cm−3 were obtained in GaAs by rapid thermal oxidation (RTO) of Si cap film in pure O2 with pressure 2 torr at 800 ∼ 900 ° C. SIMS revealed the presence of various degrees of interdiffusion in / near the interface between Si and GaAs as being a function of oxidation temperature and cap thickness. Ga and As atoms were observed in Si film. Silicon and oxygen were also found in the GaAs wafer. The silicon and arsenic atoms were segregated in / near the interface. The Si atoms could be driven further into GaAs by additional rapid thermal annealing (RTA) process. The above phenomena were confirmed by the electrical measurements taken on sheet resistance, doped dose, and mobility. The TaSix / GaAs Schottky barriers were also fabricated. The ideality factor, Schottky barrier height, and breakdown voltage are the functions of the doping level. This behavior could be accounted for by the theory of tunnel effect of Schottky barrier.