| Summary: | 碩士 === 國立中央大學 === 機械工程學系 === 105 === In this study, ultra-thin hydrogenated amorphous silicon passivation layer (< 10 nm)was prepared on silicon substrate by using silane (SiH4), hydrogen (H2) and argon (Ar) to apply silicon heterojunction (SHJ) solar cells. The chamber of PECVD processing environment will affect the quality of growing intrinsic passivation layer due to the fact that SHJ solar need a very thin passivation layer. It is our focus of this study on how to maintain processing an excellent passivation layer in a better pre-coating environment. Therefore, the changes of the pre-coating environment in PECVD were investigated.
The results show that the passivation film with no pre-coating has a carrier lifetime of 24us, but after pre-coating its carrier lifetime up to 800us. The difference between pre-coating environment and without pre-coating environment can be analyzed by Optical Emission Spectroscopy (OES) and Quadrupole mass spectrometry (QMS). It is found that an appropriate environment of pre-coating established as follows：the absolute intensity of SiH* needs to be saturated, the ratio of Si*/SiH* is 0.3~0.4, the ratio of SiH2/SiH4 to reaches the lowest point, the water vapor is reduced to 2x106(c/s), by-products of F after cleaning needs to be reduced and thickness control on the pre-coating is 1800nm~1900nm. The best pre-coating environment in the PECVD system can be obtained from above experimental and analytical results.
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