ZnSe/MgCdS and ZnCdS/MgCdS superlattices were grown on semi insulating (001) oriented GaAs substrates by molecular beam epitaxy (MBE). The crystal quality and optical properties were examined for both superlattices. The observed photoluminescence (PL) peak intensity of ZnCdS/MgCdS was much stronger than that of ZnSe/MgCdS while ZnSe/MgCdS showed sharper luminescence line width. The PL peak energy position was compared with the theoretical value derived from the Kronig-Penny model. The degradation of crystal quality was observed by increasing Mg content in MgCdS layer and drastic PL property degradation was observed when the Mg content in the layer exceeded a certain value. Two superlattices were applied to the UV-A sensor of the metal-semiconductor-metal (MSM) configuration. Both photodetectors exhibited a high sensitivity in the UV-A region with a sharp cut-off in the visible wave-length region; the ON-OFF ratio of sensor was about 103 for both structures.
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