X‐Ray, Photoluminescence, and SIMS Characterization of InGaAs / InP Grown by Vapor Phase Epitaxy

Abstract

X‐ray double crystal diffractometry (DCD), low temperature photoluminescence (PL), and secondary ion mass spectrometry (SIMS) have been used to characterize single epitaxial layers grown by hydride‐, chloride‐, and levitation‐vapor phase epitaxy (VPE). Coherent hydride layers exhibited both bound exciton and C related donor‐acceptor peaks, and the deduced bandgaps and alloy compositions were found to agree with published values. For coherent hydride‐VPE layers shifts of no more than 1 meV in the PL spectra for various positions on the wafer were observed. A layer found to be incoherent by DCD, on the other hand, exhibited luminescence shifted by up to 9 meV for various positions on the wafer. We conclude that large variations in PL spectra as a function of position on a wafer are indicative of an incoherent epitaxial layer. Incoherent layers were found by PL to contain C and Si acceptor impurities and by SIMS to have an increased S impurity content compared to coherent layers. A heavily Zn doped sample exhibited PL features similar to those of heavily Zn‐doped which were explained by invoking contributions from k‐nonconserving transitions. One of the chloride‐VPE layers also exhibited C and Zn related donor‐acceptor recombination. The PL spectrum of a levitation‐VPE sample exhibited both bound exciton and donor‐valence band recombination and, in addition, a weak Si acceptor related donor‐acceptor peak. This levitation‐VPE sample was found by SIMS to have a large Si impurity content. We infer that substitutional Si can reside on either a III or a V site in this material and is largely self‐compensating.