Molecular beam epitaxy growth and characterization of two-six materials for visible semiconductor lasers

This thesis proposes the molecular beam epitaxy (MBE) growth and characterization of a new {dollar}rm Znsb{lcub}x{rcub}Cdsb{lcub}y{rcub}Mgsb{lcub}(1-x-y){rcub}Se{dollar} based semiconductor materials system on InP substrates for visible light emitting diodes (LED) and lasers. The growth conditions for lattice-matched {dollar}rm Znsb{lcub}x{rcub}Cdsb{lcub}y{rcub}Mgsb{lcub}(1-x-y){rcub}Se{dollar} layers with the desired bandgap have been established and optimized. A chemical etching technique to measure the defect density of {dollar}rm Znsb{lcub}x{rcub}Cdsb{lcub}y{rcub}Mgsb{lcub}(1-x-y){rcub}Se{dollar} materials has been established. The accuracy of this method for revealing stacking faults and dislocations was verified by plan-view TEM. Using the techniques such as III-V buffer layer, Zn-irradiation, low-temperature growth, ZnCdSe interfacial layer and growth interruption to improve the quality of the interface of III-V and II-VI, the material quality of {dollar}rm Znsb{lcub}x{rcub}Cdsb{lcub}y{rcub}Mgsb{lcub}(1-x-y){rcub}Se{dollar} has been improved dramatically. Defect density has been reduced from 10{dollar}rmsp{lcub}10{rcub} cmsp{lcub}-2{rcub}{dollar} to {dollar}{lcub}sim{rcub}5times10sp4 rm cmsp{lcub}-2{rcub}.{dollar} The properties of this material system such as the quality and strain state in the epilayer, the dependence of bandgap on temperature, and the band offset have been studied by using double crystal x-ray diffraction, photoluminescence and capacitance voltage measurements.; The ZnCdSe/ZnCdMgSe based quantum well (QW) structures have been grown and studied. Optically pumped lasing with emission range from red to blue has been obtained from ZnCdSe/ZnCdMgSe based separate-confinement single QW laser structures. The results demonstrate the potential for these materials as integrated full color display devices. Preliminary studies of the degradation behavior of ZnCdSe/ZnCdMgSe QW were performed. No dark line defects (DLDs) were observed during the degradation.; A very strong room temperature differential negative resistance behavior was observed from {dollar}rm Al/Znsb{lcub}0.61{rcub}Cdsb{lcub}0.39{rcub}Se/nsp+{dollar}-InP devices, which is useful in millimeter-wave applications. We also found that these devices can be set to either in highly conductive or nonconductive state within a given probing voltage region, which can be used as nonvolatile memories.