Si Nanowire-Based Photovoltaic Devices Prepared at Various Temperatures

Si nanowire (NW)-based photovoltaic devices were fabricated using NWs grown at various temperatures. It was found that the average length and average diameter of the NWs increased as the growth temperature was increased from 450°C to 620°C. It was also found that the NWs became sparser with increasing growth temperature. The reflectance spectra and I-V characteristics indicate that the average reflectances were about 9%, 15%, and 18% and that the photovoltaic conversion efficiencies were 4.1%, 2.33%, and 1.87% for Si NWs grown at 450°C, 550°C, and 620°C, respectively. The experiment results show that the largest fill factor (74%) and external quantum efficiency (40%) (for a wavelength of 740 nm) were achieved for Si NWs grown at 450°C.