OMVPE growth of undoped and Si-doped GaAs epitaxial layers on Ge

Abstract

Low-pressure organometallic vapor-phase epitaxial (LP-OMVPE) growth of undoped and Si-doped GaAs on Ge was carried out with a variation in growth temperature and growth rate. In the case of undoped and Si-doped GaAs, etch patterns showed that the epilayers consist of a single domain. Double crystal X-ray diffraction (DCXRD) indicated the compressive GaAs and the full-width at half-maxima for Si-doped GaAs decreased with increasing growth temperature. The 4.2 K photoluminescence (PL) spectrum of the undoped GaAs showed an acceptor bound excitonic peak (A⁰X transition) at 1.5125 eV and the Si-doped GaAs showed two hole transitions of Si acceptors at 1.4864 eV along with the excitonic peak at 1.507 eV. This indicated the absence of Ge related peaks, i.e., (e-Ge_As⁰) transitions. The electrochemical capacitance voltage profiler showed that the Si-doping efficiency for GaAs on Ge was less than that in GaAs on GaAs. The profiler revealed an npn structure in both the cases where the p region was in GaAs. The secondary ion mass spectroscopy (SIMS) results qualitatively indicated the absence of outdiffusion of Ge into GaAs.