ABSTRACT
There is a consensus in the literature (see, for example, Refs. [3, 4]) based on X-ray photoelectron spectroscopy (XPS) and electrical data that As and As oxides are not desirable on GaAs. These leave dangling bonds; only pure Ga2O3 gives the lowest surface state density. Gentle processes like ozone oxidation, low-energy plasma, photoexcitation by ultraviolet (UV), sulfur passivation, and numerous other approaches have been tried. However, the goal of unpinning GaAs or other III-V compound semiconductors and creating surface inversion that is needed for a MOSFET-like operation has not been achieved. Ternary compounds are more useful for growing the top oxide layer, particularly in devices of the type that use high-mobility InGaAs as the channel layer and a larger-bandgap material on top under the gate.
