Mn-doped GaN studied by ultrafast optical spectroscopy
Kung-Hsuan Lin1*, Jinn-Kong Sheu2
1Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
2Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan
* Presenter:Kung-Hsuan Lin
GaN-based semiconductors have been widely applied for LED, but the intrinsic property of wide bandgap makes it improper for photovoltaic applications. Recently, the conversion efficiency of GaN-based solar cells has been greatly improved because the Mn dopants could induce extra absorption bands in the visible range. For optimization of conversion efficiency for intermediate-band solar cells, the relaxation times of different states are important parameters. We utilized ultrafast optical spectroscopy to investigate the carrier dynamics of Mn-doped GaN. The lifetime of carriers in the Mn-related intermediate bands (at 1.5 eV above the valence band edge) is around 1.7 ns. Detailed carrier dynamics within the Mn-induced bandtail states will be presented. Nonliear optical processes such as two-photon and multi-phonon absorption will also be discussed in the talk.

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