Electrical characterization of impurity-free disordered p-type GaAs

Abstract

Impurity-free disordered p-GaAs epi layers by SiO2 or native oxide capping are characterized using deep level transient spectroscopy (DLTS) and capacitance-voltage measurements. Samples, including an uncapped epi layer for reference, were annealed at 900°C for 30 s under Ar ambient. Disordering resulted in an increase in the free hole concentration with the effect being more pronounced for the SiO2 capping layer. DLTS measurements revealed the corresponding increase in the concentrations of both the Cu and Zn-related deep levels in the disordered epi layers. We relate these changes in electrical properties to segregation effects resulting from the nonequilibrium injection of excess gallium vacancies in the disordered p-type epi layers. We discuss the relative merit of using either SiO2 or native oxide layers for the integration of optoelectronic devices. Show more