Characterization of MOVPE grown InPSb/InAs heterostructures

InPSb was grown by low pressure metal-organic vapour phase epitaxy (LP-MOVPE) on InAs at temperatures between 520°C and 570°C. The samples were analysed by Raman and photoluminescence (PL) spectroscopy and high resolution X-ray diffraction (XRD). XRD as well as PL spectroscopy demonstrate the high quality of the deposited material. Sb contents of x = 0.31–0.34 in InP1−xSbx were investigated and lattice matching on InAs was achieved as controlled by XRD. Raman spectra of micron thick InPSb layers display InSb-like and InP-like phonon features and an additionally weak structure related to liberated Sb. p-type doping of the InPSb with diethylzinc or H2S causes a change of the lattice constant as indicated by XRD. The Raman spectra of the doped samples reveal changes in the lineshape of especially the InP-like phonon structure. Moreover, these changes differ for n- and p-type doping, which is interpreted in terms of free carrier contributions to the spectra via plasmon-phonon coupling. The predicted miscibility gap and its consequences for future opto-electronic applications are discussed with respect to the growth conditions and the doping.