Some Properties of Evaporated and Sprayed CdSe Layers for Heterojunction Vidicon Targets

Abstract

This chapter discusses some properties of evaporated and sprayed CdSe layers for heterojunction vidicon targets. Heterojunction layer systems have been used as targets for vidicon-type camera tubes have been widely studied. The most interesting point is that such systems enable use to be made of highly sensitive photoconductive materials such as II–VI compounds by overcoming the well-known problem of low resistivity, which results in poor storage characteristics. The vacuum evaporation and spraying of CdSe for vidicon targets have been studied in detail. The results of optical and Hall mobility measurements suggest that the photoconductive properties of the sprayed layers can be at least as good as that of the vacuum deposited ones. Completed and measured as vidicon targets, the sprayed layers had about 1–5 to 2 times higher integral sensitivity than the vacuum deposited layers. The typical sensitivity of the sprayed layers was 3000 μA lm −l , and the highest sensitivity found was 3920 μA lm −1 . It is found that image nonuniformities, if they occur, seem to correspond with the defects in and on the surface of the layers and they are more frequent with sprayed layers than in vacuum deposited ones.