High-Efficiency Delta-Doped Amorphous Silicon Solar Cells Prepared by Photochemical Vapor Deposition

Abstract

Amorphous Si solar cells with delta-doped (δ-doped) p-layers were prepared by a multichamber photochemical vapor deposition (photo-CVD) system. By optimizing the structure of the δ-doped p-layer, a conversion efficiency of 12.3% (AM1) was obtained for small-area solar cells with a δ-doped p-layer using B₂H₆ as a dopant source. The δ-doped p-layers deposited with trimethylboron (TMB) and triethylboron (TEB) as new boron sources were characterized. It was found that the boron layers obtained with TMB by photo-CVD contain a large amount of carbon atoms which degrade the solar cell performance. Carbon contamination was suppressed both by the plasma CVD method with a gas mixture of TMB, H₂ and He and by the photo-CVD method with TEB.