Effects of n-type hydrogenated microcrystalline silicon oxide film on performance of a-Si/c-Si heterojunction solar cells

In this work, we studied the effect of alternative n-type doped layer by using hydrogenated microcrystalline silicon oxide (µc-SiOx∶H(n)). The experimental results indicate that the solar cell with µc-SiOx∶H(n) has a larger short-circuit current density (Jsc), while a lower fill factor (FF), compared to the cell with n-type hydrogenated amorphous silicon (a-Si∶H(n)). External quantum efficiency (EQE) shows that the increase of Jsc is related to wider band gap and lower optical absorption of µc-SiOx∶H(n). Numerical simulation of device performance suggests that the lower FF is due to a larger band offset at the i/n interface caused by lower electron affinity of µc-SiOx∶H(n) materials. The details of the experiment and device characterization, such as the IV performance and EQE spectrum of cells using different n layers, transmittance and reflectance of different i/n stack layers, Raman spectra comparison, and band diagram characterization, will be presented in this paper.