Deep level emission in polycrystalline CuGaSe
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Polycrystalline CuGaSe<inf>2</inf>thin-films with various Cu-contents were deposited by three-stage co-evaporation method. Radiative transitions in the CuGaSe<inf>2</inf>were studied by micro-photoluminescence technique in relation to the Cu/Ga ratio in the films. In addition to a peak DAP1 around 1.60 eV, a peak DAP2 at relatively lower energy of 1.35 eV and a broadened deep-level emission DL roughly centered at 1.05 eV were observed in the photoluminescence (PL) spectra of the CuGaSe<inf>2</inf>films. Excitation-power dependence along with temperature dependence of the PL suggests that dominant recombination mechanism due to donor–acceptor pair recombination at lower temperature becomes impurity-to-band transition at higher temperature for all the three peaks. A deep donor-level, roughly 630 meV below the conduction band, which corresponds to DL-emission has been confirmed, and was investigated further in relation to the compositional variation in the CuGaSe<inf>2</inf>films.
- Jpn. J. Appl. Phys.
Jpn. J. Appl. Phys. 57(8S3), 08RC02, 2018-06-06
Institute of Physics