Ultrafast carrier dynamics in Cu(In,Ga)Se₂ thin films probed by femtosecond pump-probe spectroscopy.
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.
Department of Electro-Physics, National Chiao-Tung University, Hsinchu, Taiwan.
Shih-Chen
SC
Chen
Yu-Kuang
YK
Liao
Hsueh-Ju
HJ
Chen
Chia-Hsiang
CH
Chen
Chih-Huang
CH
Lai
Yu-Lun
YL
Chueh
Hao-Chung
HC
Kuo
Kaung-Hsiung
KH
Wu
Jenh-Yih
JY
Juang
Shun-Jen
SJ
Cheng
Tung-Po
TP
Hsieh
Takayoshi
T
Kobayashi