X-ray, photoluminescence, and SIMS characterization of InGaAs/InP grown by vapor phase epitaxy

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 the 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. The authors 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 Z-doped GaAs which were explained by invoking contributions from k-nonconserving transitions