PASSIVATION OF GAAS(100) WITH AN ADHESION-PROMOTING SELF-ASSEMBLED MONOLAYER

In this paper we demonstrate that photoluminescence (PL) from GaAs exp osed to (3-mercaptopropyl)trimethoxysilane (MPT) exhibits a 10-fold en hancement over that of an oxidized sample. The PL enhancement is attri buted to the formation of sulfur-surface bonds. We demonstrate that th e MPT surface film that results from the treatment described herein is a monolayer thick by ellipsometry, and we examine the composition of the GaAs/MPT interfacial region using X-ray photoelectron spectroscopy (XPS). The XPS results indicate that the native oxide is removed by t he etching procedure, and reoxidation of the surface is minimal during the subsequent deposition of MPT. The nature of the sulfur-surface bo nd is discussed in view of the XPS results reported here and those of previous measurements by other researchers. The self-assembled monolay ers of MPT that forms on the GaAs surface leave a trimethoxy-silyl ter minated surface that can be polymerized by exposure to weak acid. We d emonstrate that the polymerized overlayer inhibits reoxidation of the GaAs surface better than the nonpolymerized, MPT treated surface.