| Summary: | 碩士 === 國立中興大學 === 電機工程學系所 === 102 === Optimization the quality of i-layer can improve the optical, structural and electrical properties of a-Si:H p-i-n solar cell. In this thesis, a-Si:H thin-film solar cells were fabricated using 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) technique by modulation initial gas flow for i-layer deposition.
Changing the initial gas flow can control the inital plasma chemistry to alter the initial growth of the i-layer. The influence of this change on the performance of a-Si:H p-i-n solar cells were investigated. The initial gas flow control were divided into two modes (a) pre-treatment SiH4 gas flow. This mode was controlled using H2 fill up vacuum chamber to reache the target pressure, then feeding SiH4 gas in a few second before ignition the plasma. (b) Gradually increased SiH4 gas flow. The SiH4 gas flow was gradually increased before and after plasma ignition.
The results of pre-treatment SiH4 gas flow showed that the effects of changing the waiting time were no substantial influence on the performance of the solar cells. The results of gradually increasing SiH4 gas flow showed that increasing the waiting and delay time could increase the open-circuit voltage (Voc) and fill factory (FF). Gradually increasing SiH4 gas changed the hydrogen dilution ratio, which had the functions of hydrogen passivation on the surface of the p-layer, and reduction the high dissociation of SiH4 in plasma. The film density could be increased and the defects would be reduced.
Increasing the watting and delay time of gradually increasing of SiH4 gas flow could improve the performance of solar cells. The solar cell fabricated by watting time (-79s) and delay time (+104s) could obtain the energy conversion effiency of 7.05 %, Voc of 0.873 V, short-circuit current density of 11.62 mA/cm2, and FF of 69.5 %.
|
|---|
