Acceptor Delta-Doping in GaAs

Abstract

AbstractWe have investigated the formation and diffusion of delta-doped layers in GaAs employing the acceptors Zn, Cd, and C. Organometallic Vapor Phase Epitaxy was used for the growth of the Zn and Cd δ-doped layers while Metalorganic Molecular Beam Epitaxy was utilized to achieve C δ-doping. The narrowest atomic profiles for Zn had full width at half maxima of 80 Å for peak Zn concentrations of ≤ 3 × 1018 cm-3, as measured by SIMS. An effective diffusion coefficient of ≤ 7 × 1017 cm2/s is estimated for a growth temperature of 625°C, based on multiple Zn δ-doped layers. For carbon, a doping spike of 7 × 1019cm-3 with a full width at half maximum of 50Å, as measured by electrochemical capacitance voltage profiling, was achieved and represents the highest doping level yet reported for planar doping. By contrast, it was difficult to achieve doping levels ≥ 4 × 1017 cm-3 for Cd due to its high vapor pressure.