Electrical Properties of (CuO)x-(ZnO)1-X / GaAs Heterojunction Solar Cell Grown by Pulse Laser Deposition

(CuO)x-(ZnO)1-X thin films with different x content (0,0.2,0.4, 0.6, and 0.8) have been prepared by pulse laser deposition technique at room temperatures (RT). The (CuO)x-(ZnO)1-X film was deposited on GaAs substrate to form the (CuO)x-(ZnO)1-X / GaAs heterojunction. The influence of varying x content (0, 0.2, 0.4, 0.6, and 0.8) wt.% on structural and optical properties of (CuO)x-(ZnO)1-X thin films have been investigated. The X-ray diffraction analysis indicated that all films have polycrystalline nature and the phase changes from hexagonal wurtzite structure to monoclinic structure with increasing CuO content. It is noticed from AFM that the grains uniformly distributed with homogenous structure. The optical absorption spectra showed that all films have direct energy gap, and it is transparent within the visible wavelength region. The band gap energy of these films decreased with increasing x-content. electrical properties of C-V measurements at two frequencies (100, 200) kHz and I-V measurements under dark and light condition have been studied, C-V measurements for heterojunctions show an increment in built in voltage (Vbi) with increasing x content, Also width of depletion layer (w) increase with increasing of the x content for all samples at two frequencies (100, 200)kHz. while the carrier concentration (Nb) decreases with increasing of x content. I-V measurements for heterojunctions show that the mechanism of the forward current coincides with the recombination- tunneling mechanism. The dark and photo current increases with increasing x content for all samples. The short-circuit current (Isc) open circuit voltage (Voc), and fill factor ( F.F)have been studied, The best achieved efficiency was obtained around 6.3 % at (x=0,) also the value efficiency for (CuO)x-(ZnO)1-X / GaAs heterojunction decreases with increasing of x content for all samples.