In this paper n-CdSe/p-Si heteroj unction photodetector was fabricated by
thermal-evaporation technique of CdSe thin film grown onto single crystalline Si
substrate . The energy gap of CdSe film was estimated from transmittance spectra
and found to be (1.89 eV) . The temperature dependence of Seebeck coefficient
was studied . The conductivity of CdSe thin film is n-type and the value of
activation energy is (0.59 eV). Heterojunction properties included dark and
illuminated current-voltage (I-V) and capacitance-voltage (C-V) characteristics.
From I-V plot, junction ideality factor for heterojunction was calculated to be
1.43, and providing information about the current transport mechanism. The linear
variation of the experimental curve C-2 vs. V is indicative of the presence of
abrupt heterojunction and it used to determine the experimental value of built-injunction
potential Vbi . From illuminated I-V plot at different intensity levels
(90,180,240) mW/cm2 , the linearity behavior of CdSe/Si heterojunction was
investigated .