Indium doped zinc oxide thin films were deposited on p-type Si (100) substrates using ultrasonic spray pyrolysis technique (ZnO:In/p-Si heterojunction). The structural, morphological and optical properties of In-doped ZnO films have been investigated. The X-ray diffraction spectra and scanning electron microscopy measurements indicated that the films are of polycrystalline nature with (002) preferential orientation and a surface morphology almost homogeneous. The photoluminescence measurements showed that the films present some intrinsic defects such as oxygen vacancies and zinc interstitials. Current-voltage and capacitance-voltage (C-V) measurements revealed an ideality factor (n) values (in the range of 1,12 to 2,82), which are higher than unity due to the oxide layer and the presence of interface states between the two semiconductor materials. The barrier height is in the range of 0,65-0,73 eV and the junction built-in voltage deduced from C-V measurements is in the range of 0,64-0,94 Vat room temperature. (C) 2017 Elsevier B.V. All rights reserved.