Bandgap engineering on growth and properties of Cu(In,Ga)Se2 thin films for solar cell application

• Main Authors: Wang, Yi-Chih, 王奕智
• Other Authors: Shieh, Han-Ping
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/ck4n89

博士 === 國立交通大學 === 光電工程研究所 === 103 === This dissertation aims to develop an improvement of the Cu(In1-XGaX)Se2 (CIGSe) solar technology by bandgap modulation engineering based on modified selenization manufacturing. The bandgap values exhibit dominant effects on electrical performances. Several issues that bring about inadequate band distribution of CIGSe are suspended for year, such as elementary diffusion, incomplete selenization of phase segregation, toxic reactant materials, etc. Furthermore, to satisfy the environment-safe issue, the toxic reactant (H2Se gas) extensively used in selenization process was replaced by elemental selenium vapors in this work. We investigated the effect of selenium environment during the selenization procedure on the CIGSe crystallinity. A pre-heating treatment (PHT) is proposed to suppress the inhomogeneous and segregated phases by incorporating selenium elements into the precursors. Afterwards, we proposed a post gallium diffusion (PGD) process to adjust the band structure of CIGSe films. The CIGSe thin film has been demonstrated with pure chalcopyrite phase, well-crystallized morphology, and in-depth double-graded bandgap distribution through the film. This work explored the physics of crystalline CIGSe thin-film deposition to increase solar efficiency and the potentiality for improving thin-film solar applications.