Tungsten-germanium (W–Ge) oxide composite thin film was grown on the p-type Si wafer which already has an Al ohmic contact, with the co-deposition technique by using magnetron sputter method and Al/Si/W–Ge oxide composite heterojunction was fabricated. The active layer surface analysis was determined by Scanning electron microscopy (SEM) and it was observed that it has a homogeneous surface morphology. The distribution and weight percentage of elements that formed to thin film was determined by Energy dispersive X-ray spectrometry (EDX). It was found that W, Ge and O are homogenously distributed in the film. Electrical properties of fabricated heterojunction were characterised under forward and reverse bias at different light intensity. It was obtained that diode ideality factor (n) and series resistance (Rs) dropped up to 2.98 and 5Ω, respectively and also barrier height (∅b) took the values between 0.38 to 0.32eV. Additionally, photocurrent, photoresponsivity, photosensitivity and photovoltaic parameters of the heterojunction were calculated under different light intensity. It was determined that the heterojunction exhibited typical photodiode behaviour and the maximum fill factor (FF) value was 0.3084 under 60mW/cm2 light intensity.