Identification of a vanadium-related level in liquid encapsulated Czochralski-grown GaAs

Abstract

We present the first positive identification of a vanadium-related electron trap in V-doped GaAs crystals grown by the liquid encapsulated Czochralski technique in pyrolytic boron nitride crucibles. Detailed deep level transient spectroscopy and capacitance transient analysis yielded a trap energy of 0.15±0.01 eV below the conduction band and an electron capture cross section of about 2×10−14 cm2. Optical absorption and mobility data show that this level corresponds to the ionized acceptor state V2+(3d3) of substitutional vanadium. No midgap levels other than EL2 could be detected in these V-doped crystals showing that doping with vanadium plays no direct role in the compensation process in semi-insulating GaAs crystals.