Thin p-type microcrystalline silicon film on various substrates

Thin (<20nm) p-type microcrystalline silicon films have been deposited by PECVD in an unusual parameter regime, specifically optimized for extremely thin films. High conductivity (>10(-2) Scm(-1)) and low activation energy (<0.08eV) of thin films have been achieved on various metal oxide substrates i.e., Coming 7059 glass, SnO2:F, TiO2 and Ta2O5. Crystallinity was confirmed by Raman spectroscopy and UV reflectance. Deposition of p-mu c-Si:H is possible on void rich films (a-SiC:H and low temperature deposited a-Si:H) but not on device quality a-Si:H. Cells made in a superstrate structure using p-mu c-Si:H as the window layer directly on top of SnO2:F coated glass yielded 9.63% efficiency, with an improvement in the blue spectral response compared to the cell made with a-SiC:H(B) as window layer. Tandem cells (a-Si:H/a-Si:H) incorporating p-mu c-Si:H along with n-mu c-Si:H in the tunnel junction yielded 8.8% efficiency.