We study the effects of a-Si:H and mu c-Si:H covering layers and an H-2 treatment on the characteristics of mu c-Si:H thin film solar cells deposited in open single chamber very high frequency plasma enhanced chemical vapor deposition systems. Secondary ion mass spectrometry is used to evaluate the phosphor concentration in the mu c-Si:H material. Compared to use of an a-Si:H covering layer, use of a pc-Si:H covering layer reduces dopant contamination by a relative 50%, and improves efficiency by a relative 6%, and use of an H-2 treatment reduces dopant contamination by a relative 64%, and improves efficiency by a relative 17%. (C) 2011 Elsevier B.V. All rights reserved.