We found that for O content as high as similar to 2 x 10(19) at./cm(3), hydrogenated nanocrystalline silicon (nc-Si:H) solar cell having 10.6% efficiency is attainable, when a small amount of B similar to 1-3 x 10(16) at./cm(3) is incorporated. Micro-doping compensation is critical for high efficiency nc-Si:H cells absent very low residual impurities. Quantum efficiency (QE) loss in the long wavelength region is observed when O is present, which loss can be eliminated by micro-doping with a compensating element such as B. However, when the B content exceeds a certain compensation level, a QE loss in short wavelength region is observed. (C) 2012 Elsevier B.V. All rights reserved.