Fabrication and photovoltaic effect of ZnO/silicon nanopillars heterojunction solar cell

A 300 nm thickness layer of zinc oxide (ZnO) film covers on the p-type silicon nanopillars surface to heterojunction solar cell. The original nanopillars are about 200 nm average diameter and 1 A mu m height with narrow-top and wide-root morphology, which is easy to film pack. The ZnO film covers on the silicon surface by RF magnetron sputtering. Next, a layer of ITO film is sputtered on the front side of ZnO surface. Finally, the Ti/Ag are deposited onto the surface of ITO film as electrodes. The X-ray diffraction pattern shows that the crystalline ZnO grows on the nanopillars surface at different crystal orientation. On the one hand, the nanopillars wafer has lower reflectance than the planar one both before and after the ZnO film covering, which is helpful for photovoltaic performance improvement. On the other hand, the nanopillars have the large surface ratio, which can increase the light absorption and the heterojunction surface. The photovoltaic conversion efficiency of the nanopillar solar cell is 1.20%, which is higher than 1.09% that of the planar one.