Copper doped Zinc oxide and (n-ZnO / p-Si and n-ZnO: Cu / p-Si) thin films thru thickness (400±20) nm were deposited by thermal evaporation technique onto two substrates. The influence of different Cu percentages (1%,3% and 5%) on ZnO thin film besides hetero junction (ZnO / Si) characteristics were investigated, with X-ray diffractions examination supports ZnO films were poly crystal then hexagonal structural per crystallite size increase from (22.34 to 28.09) nm with increasing Cu ratio. The optical properties display exceptional optically absorptive for 5% Cu dopant with reduced for optically gaps since 3.1 toward 2.7 eV. Hall Effect measurements presented with all films prepared pure and doped have n-types conductive, with a maximum carriers concentrate of 3.9×1016 (cm-3 ) besides lower resistivity of 59.6 (Ω.cm) for films doped with 5% (Cu). The current- voltage (I-V) characteristics of heterojunction below illumination by incident power density (100 mW/cm2 ) showed that heterojunction (n-ZnO: 5%Cu / p-Si) has maximum efficiency (η =3.074 %).
