Thin film silicon n–i–p solar cells deposited by VHF PECVD at 100 °C substrate temperature

The applicability of the very high frequency (VHF) plasma-enhanced chemical vapor deposition (PECVD) technique to the fabrication of solar cells in an n–i–p configuration at 100 °C substrate temperature is being investigated. Amorphous and microcrystalline silicon cells are made with the absorber layers grown in conditions close to the amorphous-to-microcrystalline transition, which proved to give the best quality layers. It was observed that post-deposition annealing at 100 °C resulted in a relative increase of the efficiency of up to 50% for both amorphous and microcrystalline cells. For an amorphous solar cell deposited on stainless steel foil with a non-textured back reflector, an efficiency of 5.3% was achieved. A too rough substrate (textured back reflector), with an rms roughness higher than 80 nm, was found to give rise to shunting paths.