Abstract
High pressure photoluminescence techniques have been used to investigate bulk and heterostructure properties in a number of III-V semiconductor materials systems. The results are reported in this thesis along with a description of the experimental procedures. The indirect band-gaps of a series of InxGa1-xSb/GaSb quantum-wells have been measured. The results have been extrapolated to zero indium content to give the indirect band-gaps of bulk GaSb; values quoted in the literature vary widely. We obtain results consistent with accepted values but cannot refine them due to experimental errors arising from using ruby as a pressure gauge. A development of the experimental technique is proposed which would eliminate this source of error. The low-temperature F and X band-gaps have been determined in bulk (AlxGa1-x)0.5In0.5P functions of composition; we obtain E8(T)=(1.985+0.61x)eV and E8(X)=(2.282+0.085x)eV respectively. Lower limits have been put on the position of the L minima in this system and 1% compressively strained Ga0.38,In0.62P. Band offsets have been determined in unstrained (y=0.5) and 1% (y=0.62) compressively strained Ga1-yInyP/(AlxGa1-x)0.5 In0.5P; we obtain Ev(meV)=63x+157x2 and Ec(meV)=547x-157x2 for the unstrained system and Ev(meV)=72+63x+157x2 and Ec(meV)=72+547x-157x2 for the strained system. Effects of atomic ordering on the conduction band of Ga0.5In0.5P have been investigated. An investigation of anomalous pressure coefficients in strained InxGa1-x As has been carried out. A strain-related reduction in pressure coefficients (similar to that reported for InxGa1-xAs/GaAs) is found in In0.67Ga0.33As/InGaAsP quantum-wells grown on [001] substrates, but not in InGaAs/GaAs grown on [111] substrates. Preliminary results from tensile samples show evidence of increased pressure coefficients. A new X-ray powder-diffraction technique is described for direct investigation of the elastic behaviour of strained InGaAs.