Growth and properties of ZnCdSSe new alloy semiconductors for short wavelength laser applications

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1. Procedures for calculating band gaps and lattice constants in the ZnCdSSe new alloy semiconductor system, and for estimating band lineups in their multilayered structures were established. The results demonstrated the ZnCdSe/ZnSSe blue-green laser and ZnSSe/ZnCdSSe ultraviolet laser structures coherently grown on GaAs and GaP substrates, respectively.2. Growth conditions of ZnSe, ZnSSe, ZnCdSe, ZnCdS, and ZnCdSSe in metalorganic molecular beam epitaxy(MOMBE)for precise lattice matching or for coherent growth on GaAs substrates were successfully established. Sulfur passivation pretreatment of GaAs was found, to be effective for atomically controled growth and for high quality epilayers and epilayer/substrate interfaces. In situ reflactive high energy electron diffraction(RHEED)monitoring was applied for the growth control of multilayered structures and successfully resulted in well defined structures.3. From crystaline and optical properties of epilayers and multilayered structures, … More heterointerface properties, interdiffusion, and band discontinuity were characterized.4. Doping of Cl and N was found to be promising for n- and p-type conductivity control, respectively.5. Optically pumped laser action was confirmed in the double heterostructures. Characterization of threshold power, quantum efficiency, and polarization revealed that band discontinuity was one of the important factors for high performance lasers.6. ZnCdSSe multilayered structures on GaP were fabricated and their fundamental properties were characterized. It was found that they possessed type-I band structure and carriers were effectively confined in well layers ; there features were promising for applications to lasers in ultraviolet region.Throughout the study, it was found that the ZnCdSSe new alloy semiconductor system possessed promising characteristics for short wavelength region laser applications ; it is strongly expected that this new alloy system well contribute to open a window for future optoelectronics. Less