Control of the Electrical Properties of AlN/thin-a-Si/GaAs MIS Diodes by GaAs Surface Pretreatments

Abstract
The influence of GaAs surface stoichiometry was investigated on the electrical properties of AlN/thin-a-Si/GaAs MIS diodes which have an amorphous Si interlayer. The structures were fabricated by an MOCVD method with surface stoichiometry control by AsH3, H2 and TMG (trimethylgallium) pretreatments. These procedures are expected to result in As-rich, As-dimer-stabilized and Ga-stabilized GaAs surfaces, respectively. For n-GaAs, the AsH3 and H2 pretreatments suppressed the frequency dispersion of the accumulation-side capacitance, while the TMG pretreatment caused increase of the dispersion. The opposite behavior was observed for p-GaAs. These facts indicate that the function of a-Si interlayers is influenced by the initial stoichiometry of GaAs surfaces.