Stability of microcrystalline silicon for thin film solar cell applications

The development of microcrystalline silicon (muc-Si:H) for solar cells has made good progress with efficiencies better than those of amorphous silicon (a-Si:H) devices. Of particular interest is the absence of light-induced degradation in highly crystalline muc-Si:H. However, the highest efficiencies are obtained with material which may still include a-Si:H regions and light-induced changes may be expected in such material. On the other hand, material of high crystallinity is susceptible to in-diffusion of atmospheric gases which, through adsorption or oxidation, affect the electronic transport. Investigations are presented of such effects concerning the stability of muc-Si:H films and solar cells prepared by plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition.