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Cd1-x-yZnxMnyTe alloys were studied using capacitance and dissipation factor measurements, to determine dielectric properties.

Capacitance and dissipation factor measurements of Zn1xMnxSe epilayers were taken at temperatures from 5 to 475 K and from 20 Hz to 100 kHz frequencies. A thermally activated relaxation contribution to the dielectric response, which requires the presence of charge redistribution, was found. Consistency in the process of activation achieved from the dissipation factor and capacitance was also observed.

Energy-dispersive x-ray diffraction studies were performed to analyze the structure of phase transitions under high pressure. It was observed that the zinc blende to rock salt phase transition pressures of Zn0.93Mn0.07Se and Zn0.76Mn0.24Se bulk crystals are 11.8 +/- 1.5 and 9.9 +/- 0.5 GPa, respectively. The respective bulk moduli are 61.8 +/- 0.8 and 60.5 +/- 0.8 GPa. The pressure-induced zinc blende to rock salt structure phase transition was seen as an indication of the semiconductor to metal transition for Zn(sub 1-x)Mn(sub x)Se.

Reflectance spectroscopy was utilized to examine the light hole and heavy hole exciton splitting of ZnSe1-xSx epilayers that were grown on misoriented gallium arsenide (001) substrates. The composition of the layers were used to determine both exciton energies. Results showed that an increase in the incorporation of sulphur was noted due to misorientation of the substrate in both thin and thick epilayers.

Research was conducted to study the optimal properties of ZnSe1-xTex semiconductor epilayers prepared by molecular beam epitaxy. Low temperature cells were utilized to evaporate elemental solid sources while sample temperatures were controlled between 10 K and 250 K. Results indicated a blueshift of the near band-edge PL with the substrate misorientation angle attributed to the incorporation of smaller atoms with the kink density.

Research was conducted to examine quantized transitions in a Zn(sub 0.79)Cd(sub 0.21)Se/ZnSe double quantum well using the contactless electroreflectance (CER) technique. This molecular beam epitaxy technique was used to develop the quantum well. Results show the existence of several intersub-band transitions in the CER spectra. Excitonic transitions were also seen between the heavy-hole band state and the conduction band state.

Polarized photoluminescence and reflectance are used to study strain-induced band splittings of ZnSe/GaAs and ZnMnSe/GaAs epilayers of 0.064 to 3 micrometers. The optical transitions are identified by polarized photoluminescence. The variations in magnetic field sensitivity of light hold and heavy hold exciton also indicate the presence of optical transitions.

The spatial isolation of electrons and holes with varying spins and the reflectance spectra of ZnFeSe/ZnSe quantum well structures are analyzed to determine the shape of the reflectance spectra. The spatial isolation of electrons with varying spins forms spin superlattices. The interference effects in layers having different thickness cause the change in the reflectance spectra.

Electron and hole spin lifetimes and spin relaxation processes in diluted magnetic semiconductor spin superlattices were investigated using dc photoluminescence analysis. The results showed that the long hole spin lifetime was due to the strain-induced splitting of the bulk-degenerate light- and heavy-hole bands at the zone center which inhibited fast spin relaxation.

The temperature-dependent reflectance (R) and photoluminescence (PL) measurements on ZnMnO films grown by plasma-assisted molecular beam epitaxy is studied. The spectral data of ZnMnO films have not only shown the deterioration of crystalline quality with increasing Mn composition fraction but has also indicated the Mn clustering caused by Mn atom segregation.

The dependence of the hot-electron energy relaxation in InN epilayers on electron density and the electron temperature of the hot electrons are determined. The density-dependent electron energy loss rate in InN is explained by a combination of longitudinal optical and acoustic phonon emissions and a slowing of the energy loss rate at high electron densities is attributed to piezoelectric coupling to acoustic phonons.

Pressure-induced resonant Raman scattering is adopted to analyze the zone-center optical phonon modes and crystal characteristics of [Zn.sub.1-x][Mn.sub.x]Te thin films. The results have shown that the manganese ions have increased the iconicity of ZnTe under ambient conditions, whereas an external hydrostatic pressure has reduced the iconicity and the bond length of [Zn.sub.1-x][Mn.sub.x]Te.

Capacitance and dissipation factor measurements at a temperature of 200K