We have prepared intrinsic hydrogenated amorphous silicon (a-Si: H) films by remote plasma chemical vapor deposition (RPCVD) using Ar and He plasma excitations. The microstructure and effective surface passivation quality of the films are characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and photoconductance decay (PCD). Our preliminary results show that films deposited with He plasma have significantly higher mono-hydride and lower di-hydride content compared with Ar films at similar deposition conditions, however PCD measurements show the effective passivation quality of these films to be comparable. Furthermore, a correlation between He flow rate, the microstructure, and surface passivation quality was found resulting in the enhancement of the effective minority carrier lifetime by 64%, from 1.1 ms (flow rate 520 sccm) to 1.9 ms (flow rate = 208 sccm).

A thin, flexible monocrystalline germanium (c-Ge) heterojunction solar cell has been developed based on a cost-effective kerfless exfoliation process and remote plasma-enhanced chemical vapor deposition (RPCVD) of hydrogenated amorphous silicon (a-Si:H). The performance of the exfoliated 50μm thick and bulk 500μm Ge heterojunction cells are compared in this paper. A superior conversion efficiency of 5.28% was achieved with the 50μm exfoliated Ge cell versus 1.78% for the bulk Ge cell, in agreement with simulation results. A record fill factor of 58.1% for an a-Si:H/c-Ge heterojunction cell is obtained with the exfoliated cell. Moreover, the conversion efficiency achieved with the 50μm exfoliated cell (without intrinsic a-Si:H passivation) is comparable to the best reported in literature with bulk Ge heterojunction cells and intrinsic a-S:H passivation.