Numerical Approach to the Investigation of Performance of Silicon Nanowire Solar Cells Embedded in a SiO2 Matrix

The electrical characteristics of silicon nanowire (SiNW) solar cells with p-type hydrogenated amorphous silicon oxide (E-g = 1.9eV)/n-type SiNWs embedded in a SiO2/n-type hydrogenated amorphous silicon oxide (E-g = 1.9eV) structure have been investigated using two- and three-dimensional device simulators, taking into account the quantum size effect. The average bandgap of a SiNW embedded in SiO2 increased from 1.15 to 2.68 eV with decreasing diameter from 10 to 2 nm, owing to the quantum size effect. Note that under sunlight of AM1.5G, the open-circuit voltage (V-oc) of SiNW solar cells also increased to 1.46 V with decreasing diameter of the SiNWs to 2 nm. This result suggests that it is possible to enhance V-oc by applying the quantum size effect, and a SiNW is a promising material for all-silicon tandem solar cells. (C) 2012 The Japan Society of Applied Physics