Strain effects and atomic arrangements of 60° and 90° dislocations near the ZnTe/GaAs heterointerface Appl.Local interface composition and extended defect density in ZnSe/GaAs(001) and ZnSe/In 0.04 Ga 0.96 As (001) heterojunctions J.The lifetime of II-VI-based blue-green laser diodes on GaAs substrates is limited by rapid degradation in the active layers. This degradation has been observed as dark defects in the active layer during the laser operation, where defects occurred due to stacking faults that originated from the Ga 2 Se 3 compounds at the ZnSe/GaAs interface. The reported value of the density of stacking faults of the II-VI lasers was in the order of 10 5 cm Ϫ2 . To extend the lifetime, surface treatment of the GaAs substrate and control of the interface reaction are necessary. We investigated a new treatment technique using hydrogen-radical and Zn/As fluxes. We fabricated ZnSe-based double-hetero ͑DH͒ structures on a treated GaAs substrate and measured the density of dark defects in the light emitter area by electroluminescence microscopy. Chemical bonds at the interface were evaluated by x-ray photoelectron spectroscopy. A dark defect density of less than 10 5 cm Ϫ2 was obtained when the As-terminated GaAs surface was Zn treated. The Zn treatment prevented the formation of the Ga 2 Se 3 layers. When we alternated the exposure between Zn and As fluxes, excess ZnAs x interfacial layers were formed and the quality of the DH structure was unacceptable. However, hydrogen-radical exposure before and during the Zn/As treatment effectively removed the excess ZnAs x compounds, and the density of dark defects fell to 2ϫ10 4 cm Ϫ2 .

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The effects of annealing on a ZnCdSe single quantum well (SQW) structure with ZnCdSSe/ZnSSe superlattice optical guiding layers are investigated. X-ray diffraction and photoluminescence (PL) measurements showed disordering of a ZnCdSSe/ZnSSe superlattice after annealing at about 500 °C. The PL peak energy of the SQW shifted to the higher energy side, and the linewidth narrowed in the sample annealed at 300 °C. Cadmium diffusion was confirmed by secondary ion mass spectrometry. We found that the disordering of the ZnCdSSe/ZnSSe superlattice and the changes in the emissions from the SQW were due to the Cd diffusion.

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