The　effect　of　plasma　excitation　frequency　on　the　performance　of　intrinsic　hydrogenated　amorphous　silicon　(a-Si:H)　films　and　heterojunction　solar　cells　by　radio-frequency　(RF,　13.56　MHZ)　and　very-high-frequency　(VHF,　40　MHZ)　plasma-enhanced　chemical　vapor　deposition　(PECVD)　have　been　investigated.　The　thickness　and　microstructure　of　intrinsic　a-Si:H　films　were　measured　by　spectroscopic　ellipsometry　and　Fourier　transform　infrared　spectroscopy　(FTIR).　The　a-Si:H/c-Si　interface　passivation　quality　were　determined　by　minority　carrier　lifetime　and　transmission　electron　microscopy　(TEM).　The　current-voltage　(I-V)　performance　of　the　HJT　solar　cells　were　also　evaluated.　The　results　reveal　that　a-Si:H　films　developed　by　RF-PECVD　with　a　large　area　of　parallel-plate　reactors　(＞　1　m(2))　exhibit　better　thickness　uniformity,　lower　microstructure　factor,　and　higher　minority　carrier　lifetimes.　Hence　HJT　solar　cells　have　achieved　efficiency　of　24.9%,　compared　with　cell　efficiency　of　24.6%　with　intrinsic　a-Si:H　films　developed　by　VHF-PECVD.