High-quality p-type a-SiC films were prepared using a new doping gas, B(CH3)3, instead of B2H6. a-SiC films deposited with B(CH3 )1 show high photoluminescence intensity and low defect density. Doping efficiency was also improved by usiyg B(CH3 )3. A module efficiency of more than 9% was achieved for a 100 cm2 a-Si solar cell whose p-layer was doped with B(CH3 )3. A new plasma CVD method, called controlled plasma magnetron (CPM) method was developed to realize high electron-density plasma with low damage to substrate. High conductive p-type μc(microcrystalline)- SiC films were prepared by CPM method with B(CH3 )3. CPM method was found to be suitable not only for preparation of μc films but for high-speed deposition.