摘要：Cone‐shaped semiconductor silicon nanowires (CS‐Si‐NWs) grown in vapor liquid solid mode are promising for the fabrication of low‐cost high‐performance solar cells because of their low processing cost and lower use of Si materials, as compared to planar devices. In this article, the effect of injected charge carriers on the refractive indices and extinction coefficient values in a cone‐shaped pin Si NW (CS‐pin‐Si NW) were considered. Then, the influence of top diameters and periods on the optical absorption was investigated using a finite difference time‐domain (FDTD) modeling method. The absorption increased when we decreased the period from 300 to 150 nm for a light wave with a wavelength of 700 nm. However, in the case of incident light at a wavelength of 500 nm, the absorption significantly increased by up to 100% and was found to be independent of the period. On the other hand, we varied the period and the top diameter of the NWs with a fixed bottom diameter. In this case, we found that the period did not significantly affect the absorption value. A high value of the short circuit current density of 19.5 mA/cm2 was found in the case of NWs with a top diameter of 110 nm and a period of 150 nm. Combined with the analysis of the ultimate photocurrents, an optimum geometric structure with a top diameter of 70 nm and a period of 150 nm for a CS‐pin‐Si NW‐based top cell for tandem solar cell applications was proposed.
关键词：External quantum efficiency;finite difference time domain;silicon nanowire;solar cells
