Characterization of InGaAs surface passivation structure having an ultrathin Si interface control layer

Abstract

A recently proposed passivation structure of In0.53Ga0.47As surface is characterized by x-ray photoelectron spectroscopy (XPS), capacitance–voltage, and deep-level transient spectroscopy measurements. It uses an ultrathin molecular beam epitaxy Si interface control layer (ICL) and a photochemical vapor deposition (CVD) SiO2 outer insulator. XPS study indicates that growth of Si ICL is coherent and two-dimensional up to about 10 Å beyond which clustering is initiated, and that it is effective in preventing the InGaAs layer from selective oxidation of Ga during photo-CVD SiO2 deposition. C–V and deep level transient spectroscopy (DLTS) measurements give Nss distributions of very different shapes, the latter exhibiting two distinct peaks, which may be erroneously interpreted as defect levels. Suppression of selective oxidation of InGaAs does not alter the shapes of these distributions, although it reduces the magnitude. The results are explained by the disorder-induced gap state model rather than the defect model or the effective work function model.