Current Transport in ZnO/Si Heterojunctions for Low-Cost Solar Cells

Thin film ZnO/Si structures are being studied as candidates for low cost solar cells. Total film thickness was about 5 microns. Crystallinity of both films was verified by X-ray diffraction. Photoluminescence spectroscopy showed a very strong peak to verify the crystallinity of the ZnO. ZnO films were studied for Hall effect mobility to reveal values of up to 200 cm
²
/V-s. In some cases, laser annealing was used to modify the ZnO films. Device structures were completed using the designs of metal/p-Si wafer, metal/ MIG-Si, and metal/ZnO/MIG-Si. These were chosen to evaluate current transport of the MIG-Si and the ZnO/MIG-Si interface. I-V-T data from 150degC to 425degC revealed quite different behaviors for the 3 designs. Conduction mechanisms included thermionic emission, recombination, space charge limited current (SCLC) due to a single trap and SCLC due to an exponential distribution of traps, seen for the ZnO/MIG-Si case