Generally higher depositions temperatures are required to prepare solar cells with narrow band gap amorphous silicon intrinsic layers. High processing temperatures require that diffusion resistant substrates and doped layer materials be developed. In the case of p-i-n solar cells both a new Ga-doped ZnO and/or semi-transparent Cr over-coated standard commercially available TCO show increased resistance to high temperature processing and it is possible to prepare efficient solar cells on these substrates at temperatures over 280 C. In most amorphous silicon i-layer cases a-SiC:H p-layers offer better diffusion resistance than microcrystalline players. However, in the case of narrow band gap amorphous silicon prepared at high temperatures using the argon treatment process  micro-crystalline p-layers offer significantly improved solar cell performance. Another promising approach involves the n-i-p deposition sequence, however, this case too can suffer from diffusion related problems.