Huizhi Ren

HIGH GROWTH-RATE DEPOSITION OF μc-Si:H THIN FILM AT LOW TEMPERATURE WITH VHF-PECVD

High growth rate deposition of μc-Si:H film with VHF-PECVD at low temperature has been reported. Investigations showed that growth rates enhanced with higher excitation frequency and working pressure, but increased at first then decreased with the increase of plasma power. Optical emission spectroscopy (OES) was introduced to monitor VHF plasma. The relationship between the growth rates and the OES results has been discussed. Raman spectra were also used to study the a-Si:H/μc-Si:H phase transition. Finally a high growth rate of 2.0nm/s has been obtained through the initially optimized condition.

Research Progresses on High Efficiency Amorphous and Microcrystalline Silicon-Based Thin Film Solar Cells

This paper reviews our research progresses of hydrogenated amorphous silicon (a-Si:H) and microcrystalline (μc-Si:H) based thin film solar cells. It coves the three areas of high efficiency, low cost process, and large-area proto-type multi-chamber system design and solar module deposition. With an innovative VHF power profiling technique, we have effectively controlled the crystalline evolution and made uniform μc-Si:H materials along the growth direction, which was used as the intrinsic layers of pin solar cells. We attained a 9.36% efficiency with a μc-Si:H single-junction cell structure. We have successfully resolved the cross-contamination issue in a single-chamber system and demonstrated the feasibility of using single-chamber process for manufacturing. We designed and built a large-area multi-chamber VHF system, which is used for depositing a-Si:H/μc-Si:H micromorph tandem modules on 0.79-m 2 glass substrates. Preliminary module efficiency has exceeded 8%.

High Rate Deposition of Stable Hydrogenated Amorphous Silicon in Transition from Amorphous to Microcrystalline Silicon

High rate deposition of high quality and stable hydrogenated amorphous silicon (a-Si:H) films were performed near the threshold of amorphous to microcrystalline phase transition using a very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The effect of hydrogen dilution on optic-electronic and structural properties of these films was investigated by Fourier-transform infrared (FTIR) spectroscopy, Raman scattering and constant photocurrent method (CPM). Experiment showed that although the phase transition was much influenced by hydrogen dilution, it also strongly depended on substrate temperature, working pressure and plasma power. With optimized condition high quality and high stable a-Si:H films, which exhibit σ ph /σ d of 4.4×10 6 and deposition rate of 28.8A/s, have been obtained.