The effect of Gd doping on the electrical and photoelectrical properties of Gd:ZnO/p-Si heterojunctions

•Undoped and Gd doped ZnO thin films were deposited onto p-Si semiconductor.•The Gd:ZnO/p-Si heterojunctions were compared with undoped ZnO/p-Si heterojunction.•A strong effect of Gd doping on the performance of the devices were reported. Undoped ZnO thin films, as well as 1%, 3% and 5% Gd-doped ZnO films, were deposited on p-type Si using spin coating. The structural properties of these thin films were analysed using X-ray diffraction, and the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the Gd:ZnO/p-Si heterojunctions were compared with those of the undoped ZnO/p-Si heterojunctions. We found that Gd doping had a strong effect on the performance of the devices, and that the Gd:ZnO/p-Si heterojunctions formed with 1% Gd-doped ZnO were the most strongly rectifying, and had the highest barrier height and the lowest series resistance. Furthermore, the I–V measurements of the 1% Gd-doped ZnO/p-Si heterojunction exhibited the strongest response to light.