Large-Area P-μc-Si:H Thin Films Prepared by VHF-PECVD and its Application in Micromorph Tandem Solar Module

High conductivity,high crystalline volume fraction p-type microcrystaline silicon(p-mu c-Si:H) thin films prepared by high-pressure VHF-PECVD are reported in this paper. The effects of the boron concentration, the silane concentration and the plasma power on the microstructures and electrical characteristics of P-mu c-Si:H thin films are investigated. The results show that the microstructures and electrical characteristics of thin films relied on the deposition parameters. By optimizing the deposition parameters, very thin(31 nm) P-mu c-Si:H thin films have been obtained at the doping ratio of 0.4%, SC at 1.2% and power at 1800W. The Xc of P-mu c-Si:H thin films was 67% with 4.3% uniformity,the dark conductivity was 0.68S/cm with 5.1% uniformity. By employing this P-mu c-Si:H thin films, an initial conversion efficiency of 8.12% was obtained for a 0.79 m(2) a-Si:H/mu c-Si:H tandem module by Al as back reflector.