Use of ultraviolet/ozone cleaning to remove C and O from GaAs prior to metalorganic molecular beam epitaxy and metalorganic chemical vapor deposition

Abstract

Ultraviolet/ozone cleaning of GaAs substrates prior to metalorganic molecular beam epitaxy at 500 °C is shown to reduce the interfacial C and O concentrations by more than two orders of magnitude. Metal‐semiconductor field‐effect transistors (MESFETs) utilizing this cleaning prior to growth of the component epitaxial layers display superior current voltage (I‐V) saturation characteristics compared to identical devices grown without the cleaning step. By contrast, provided the GaAs surface is not contaminated with silicates, the atomic hydrogen generated at the growth surface during growth by metalorganic chemical vapor deposition (MOCVD) leads to lower O and C interfacial concentrations, thereby circumventing the need for ozone cleaning. MESFETs grown by MOCVD with or without this cleaning have excellent I‐V characteristics.