An application of synchrotron radiation to study the microstructure of passivation layers on GaAs

Abstract

Some of the background to the application of GaAs as a field-effect, addressable, potentiometric sensor/stimulator (FAPS) is reviewed and the need for the passivation of this material prior to its use in this application is outlined. (3-mercaptopropyl) trimethoxysilane (MPT) was deposited on a GaAs surface to provide passivation against corrosion by oxygen and to prevent AsO33- escape into the surrounding environment. X-ray reflectivity was used to probe the surface to obtain an electron density depth profile that could then be fitted to a computer model revealing the number of layers and their corresponding thicknesses, densities and roughnesses, respectively. Since GaAs surfaces are highly..