The manufacturing of Si base thin film solar cell modules

Si based thin film solar cell will be next generation of solar cell products. In order to fabricate high efficiency Si base thin film solar cell, High density (HD) and very high frequency (VHF)-PECVD technologies have been developed for high quality, large scaling ue-Si, μc-SiGe, and μc-SiC film deposition. The high-density and very high frequency plasma technique offers the significant advantages of high plasma density, low plasma potential, and independent control of ion flux and ion bombardment energy which are critical for controlling the bulk and interfacial characteristics of the deposited films. In comparison to other CVD processes, the HD and VHF-PECVD technique offers potential advantages of the deposition of higher growth rates, higher quality films at lower processing temperatures, void free gap filling of high aspect ratio features, self-planarization, lower impurity levels and large scaling capability. The experimental results show typical deposition rate of the μ-Si thin films by HD-PECVD was greater than 10 A/s, the typical microcrystalline volume fraction and the average crystallite size corresponding to 〈111〉 orientation were 75% and 160 Å, respectively. Amorphous SiGe and SiC films have been achieved, μc-SiGe, μc-SiC films are under processing. The stabilized efficiency of tandem junction solar cells with a-Si/μc-Si films can reach 12%.