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 = 1:9 eV)/n-type SiNWs embedded in a SiO₂/n-type hydrogenated amorphous silicon oxide (E_g = 1:9 eV) structure have been investigated using two- and threedimensional 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.