Abstract :
The CdSe:Cu photoconductive detector was fabricated using vacuum technique on glass substrate at different temperatures. The effect of the substrate temperatures of the prepared films upon, the structural , I-V characteristics, photoconductive properties, spectral response, quantum efficiency, NEP, gain and detectivity properties of the detector was studied. The structure of the prepared films was studied using XRD. It was found that the crystal structure is improvement with increasing doping and substrate temperatures. It was found that better photoconductive characteristics can be reached when CdSe:Cu films substrate temperature increased from room temperature up to Ts 250°C. The structure of these films are amorphous at pure CdSe with small peaks at (002) direction, and the structure with Cu impurity are polycrystalline with high intensity at the direction (002) and small peaks at the direction (102) which indicate a hexagonal and cubic structure with lattice constant (a-4.27, c=7.02)A. The crystal structure are improving from polycrystalline to single phasc(002) direction and hexagonal structure with lattice constant(c=7.02)A by increasing of substrate temperatures. It was found that the gain coefficient was increased with an increase of the substrate temperatures and better result obtained at 250°C. The CdSe:Cu detector showing gain coefficient up to 6.7x10 for white illumination lOOOLux. The maximum value of spectral response (RA) were at (0.71, 0.71, 0.69, 0.68., 0.675)iim for films prepared at substrate temperatures(28, 100, 150, 200, 250) °C respectively. This mean that the spectral response is increased with the increase of A .The highest value of RA was for films prepared at Ts =250C decreases with the decreasing of Ts. The quantum efficiency (rj) increases with the increasing Ts and the NEP decreases with increasing Ts. The maximum value of D occurs at A=(0.71, 0.71, 0.69, 0.68., 0.675)fim was equal to (1.023X1012, 1.157 X10 ^12,1.27 X10 ^12,1.39 X10 ^12 ,l .46 X10 ^12)Cm.Hzl^/ 2W^-1 forTs(28, 100, 150, 200, 250) °C respectively.
