The detection properties of of CdS/p-Si and CdS:In/p-Si heterojunction (HJs) prepared by thermal evaporation method have been studied . These films were doped with in 2% by thermal diffusion method at diffusion temperatures (Td=200,250,300,350oC). Pure n-CdS/p-Si and doped n-CdS:In/p-Si heterojunction types at different diffusion temperatures have been prepared by deposition pure and doped CdS thin films on p-type single crystal
silicon. The detectivity of these HJs is broad and lies in the range (500-1100) nm with two peaks for pure n-CdS/p-Si at 550nm and 800nm have been observed. For doped n-CdS:In/p-Si HJ the peaks were located at 650nm and 800nm and for two types of HJs the first peak was for CdS and CdS:In and the second peak was for silicon. The value of noise equivalent power (NEP) decreases with increasing diffusion temperatures (2.76, 2.42, 2.17, 1.38) x10-11
W for (Pure, Td=200, 250,300 oC) respectively and then increased to 2.13 x10-11W at 350 oC. The detectivity also increases with increasing Td (0.108, 0.165, 0.166, 0.217, 0.155) x1011cm.Hz1/2.W-1 for (Pure at 550nm, doped at 650nm for Td=200, 250,300 oC) then decreases at 350 oC.
