Photoelectronic Properties of CdSe Evaporated Films

Abstract

Pure CdSe films deposited on 100°–400°C substrates show high photosensitivity after a treatment of subsequent baking in a temperature range of 500°–700°C in argon gas. The maximum value of light-to-dark current ratio at 1000 lx is of the order of magnitude of 10⁶. The maximum peak of spectral sensitivity is in a range of 700–710 mµ. Spectral distribution of absorption coefficient of baked films is almost equal to that of single crystals. Effect of baking on deposited films was studied by measuring thermally stimulated current (TSC) and superlinearity. Trap denisty of deposited films estimated by TSC method is 10¹⁸–10¹⁹ cm^-3. Whereas, the decrease of trap density is observed in highly photosensitive films after baking, particularly for deep traps (trap density is smaller than 10¹⁴ cm^-3). Properties of sensitizing centers in baked films are observed to be similar to those of single crystals.