Si/SiOx/Si hole-barrier fabrication for bipolar transistors using molecular beam deposition

Abstract

Abstract SiOx layers were deposited on silicon substrates in a silicon MBE system by co-deposition of silicon and oxygen. The oxygen concentration increased as the deposition temperature decreased. Oxygen pressure was 5×10−5 Torr and the silicon deposition rate was 0.2 A s−1. Composition was determined by using X-ray photoelectron spectroscopy and Auger electron spectroscopy, and the electric properties of its metal-oxide-semiconductor capacitor were measured. The growth procedure used here offers high controllability in the thickness of the deposited SiOx layer and permits subsequent silicon growth in the same silicon MBE chamber. Such Si/SiOx/Si structures, which may be applied to the hole-barrier between the base and emitter layers in bipolar transistors, were also successfully grown using this method. We fabricated this type of bipolar transistor and one order higher current gain than that of usual polysilicon emitter was obtained when SiOx layer thickness was 20 A.