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 (mu c-SiOx:H(n)). The experimental results indicate that the solar cell with mu c-SiOx:H(n) has a larger short-circuit current density (J(SC)), 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 J(sc) is related to wider band gap and lower optical absorption of mu c-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 mu c-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.