Ultrafast carrier dynamics in Cu(In,Ga)Se2 thin films probed by femtosecond pump-probe spectroscopy

Shih Chen Chen*, Yu Kuang Liao, Hsueh Ju Chen, Chia Hsiang Chen, Chih Huang Lai, Yu Lun Chueh, Hao-Chung Kuo, Kaung-Hsiung Wu, Jenh-Yih Juang, Shun-Jen Cheng, Tung Po Hsieh, Takayoshi Kobayashi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Ultrafast carrier dynamics in Cu(In,Ga)Se2 films are investigated using femtosecond pump-probe spectroscopy. Samples prepared by direct sputtering and co-evaporation processes, which exhibited remarkably different crystalline structures and free carrier densities, were found to result in substantially different carrier relaxation and recombination mechanisms. For the sputtered CIGS films, electron-electron scattering and Auger recombination was observed, whereas for the co-evaporated CIGS films, bandgap renormalization accompanied by band filling effect and hot phonon relaxation was observed. The lifetime of defect-related recombination in the co-evaporated CIGS films is much longer than that in the direct-sputtered CIGS films, reflecting a better quality with higher energy conversion efficiency of the former.

Original languageEnglish
Pages (from-to)12675-12681
Number of pages7
JournalOptics Express
Volume20
Issue number12
DOIs
StatePublished - 4 Jun 2012

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