Photoelectric properties of an injection photodetector based on alloys of II–VI compounds

A photosensitive structure with high room-temperature integrated sensitivity $S_{\mathrm{int}}\approx$ 700 A/lm (14500 A/W) is fabricated based on alloys of II–VI compounds $n$-CdS$_x$Te$_{1-x}$, $p$-Zn$_y$Cd$_{1-y}$Te. Its photoelectric properties are studied at various illumination levels and bias voltages. It is found that diffusion and drift flows of nonequilibrium carriers are directed oppositely at low illumination levels and forward bias voltages. This effect leads to inversion of the photocurrent sign, which makes it possible to fabricate selective photodetectors with injection properties on its basis.