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|Type of Document
||Effect of surface passivation on carrier lifetime of textured crystalline silicon wafers|
|Date of Defense
||The purpose of this study is to investigate the surface carrier lifetime of a texturized n-type (100) Si wafer after surface passivation. The surface texturization on the Si wafer using isopropanol-free alkaline solution was performed and compared with that of using conventional isopropanol alkaline etchant. Texturization conditions, such as concentration of etchant, etching temperature, and etching time were optimized to reduce optical reflection of the Si surface. |
The surface passivation of the Si surface was first formed by growing a 1 nm thick SiOx used the supercritical carbon dioxide (SCCO2) fluid with H2O2 additive. We varied the operation pressure and time of the SCCO2, together with H2O2 concentration to optimize the performance of the SiOx passivation layer. After growing the SiOx thin film, we deposited a 30 nm thick a-Si by VHF PECVD to further improve the defects cause by the silicon dangling bond on the Si surface.
The weighted reflectivity and surface coverage of pyramid of the textured Si substrates of better than 15% and 90% were achieved. On the other hand, lifetime of the carriers was measured by a home-made photoconductance system. The effective carrier lifetime (@1015 cm-3) of texturized silicon substrate with SiOx surface passivation was 6 µs. The carrier lifetime was further increased to 26.9 µs when SiOx and a-Si double-layered passivation was used.
||Ting-Chang Chang - chair|
Chao-Kuei Lee - co-chair
Wei-Chen Tien - co-chair
Ann-Kuo Chu - advisor
Indicate in-campus at 2 year and off-campus access at 2 year.|
|Date of Submission