Structural and optical characterization of type II In0.14Ga0.86As0.13Sb0.87/GaSb heterostructure doped with zinc grown by liquid phase epitaxy

In0.14Ga0.86As0.13Sb0.87 quaternary solid solutions lattice-matched to GaSb (0 0 1) substrates were grown by liquid phase epitaxy, which were intentionally doped with Zn in a wide range. Two main vibrational bands are observed in their Raman spectra over the doping range investigated. The assignment of the observed modes to GaAs-like and (GaSb + InAs)-like mixture modes is discussed. The comparison of the experimental results with obtained ones by the modified random-element isodisplacement (MREI) model allows to confirm that the bands correspond to the vibrational modes associated with longitudinal- and transverse-optical (LO and TO) modes of the binary compounds GaAs and (GaSb + InAs). The low-temperature photoluminescence (LT-PL) of p-type InxGa1−xAsySb1−y was studied as a function of zinc concentration added to the melt solution. Low temperature photoluminescence spectra show the presence of an emission band that has been related to radiative emission involving Zn-acceptors. For low carrier concentration, the photoluminescence line shape could be explained in terms of a direct transition following a simple k-selection rule. For degenerate concentrations, however, it is properly interpreted in terms of non-k-conserving transitions which arise from indirect recombination of holes in a highly filled valence band.