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Photoluminescence study of Si doped and undoped Chalcopyrite CuGaSe2 thin films |
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| Authors: | Sathiabama Thiru Miki Fujita Atsushi Kawaharazuka Yoshiji Horikoshi |
| Institution: | 1. School of Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo, 169-8555, Japan 3. CREST, JST, 4-1-8, Honcho Kawaguchi, Saitama, 332-0012, Japan 2. Waseda Institute for Advanced Study, Waseda University, 1-6-1, Nishiwaseda, Shinjuku, Tokyo, 169-8050, Japan |
| Abstract: | Photoluminescence (PL) characteristics have been studied on undoped and Si-doped CuGaSe2 single crystal thin films grown on GaAs (001) substrate by migration-enhanced epitaxy. Room temperature PL spectrum of an undoped layer clearly shows free excitonic emission bands related to the minimum band-edge and to the split-off valence band, but no discernible emission has been observed in the low energy area. At 4.2 K, the excitonic emission due to the split-off valence band disappears. Instead, two additional emissions appear at 1.68 and 1.715 eV which are attributed to the bound exciton and band-to-acceptor transition. The Si doping to CuGaSe2 produces two additional PL bands around 1.61 and 1.64 eV. These PL bands are attributed to the donor acceptor pair emissions due to the doped Si impurity which probably occupies Cu or Ga sites and intrinsic Cu vacancy. |
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