The optoelectronic properties of CdSe:Cu photoconductive detector

Photoconductive CdSe doped with (1–5 wt%) of Cu was fabricated using the vacuum evaporation technique for thin-film preparation followed by vacuum annealing at 350°C under an argon environment for doping with copper. The electrical and detection properties as a function of Cu content were studied. It was found that the gain coefficient was increased with an increase in the Cu impurity concentration and better results were obtained for a CdSe:Cu detector of 5 wt% concentration, which showed a gain coefficient of up to 8.87×103 for white illumination ∼1000 Lux. This value is much greater than the published value for pure CdSe film, possibly due to the sensitizing action of Cu centers. Additional weak but well resolved features were observed in the high-energy region of the curve depicting gain coefficients as a function of wavelength characteristics. These peaks were attributed to the 3D transition of Cu from deep levels in the valence band.