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

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.