The effects of depth profiling and band Structure of CIGSSe solar cell elements to efficiency by using Scanning Photoelectron Microscopy

• Main Authors: CHEN-WEI HONG, 洪晨幃
• Other Authors: CHU-SHOU YANG
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/31702554937341469224

碩士 === 大同大學 === 光電工程研究所 === 103 === In this study, we investigated the depth-dependent compositions and band structure of Cu(In,Ga)(Se,S)2-based solar cell device. In order to measure the elemental composition distribution and the band structure of the multi-layered films, we polished the CIGSSe-based solar cell with a gradient thickness to probe the position (depth)-dependent variations in photoelectron signals by using scanning photoelectron microscopy (SPEM). SPEM enables us to directly “observe” the depth-dependent compositions and band structure of the thickness-gradient CIGSSe-based solar cell due to its high spatial resolution (~200 nm) in photoelectron emission. Our experimental results show that the band structure is a spike type at the interface of CdS/CIGSSe. It is also found that the concentration ratios of Ga/In+Ga and S/S+Se are higher at the interface of CdS/CIGSSe, leading to a larger band gap and a higher conduction-band minimum near the top of absorber layer. In addition, we compared the material characteristics with the other sample of lower efficiency. The reason of lower efficiency can be attributed to the conduction band offset at its interface of CdS/CIGSSe, which is larger than the sample in this study.