| 초록 |
Single crystal AgGaSe2 layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 420 ℃ with hot wall epitaxy (HWE) system by evaporating AgGaSe2 source at 630 ℃. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal AgGaSe2thin films measured with Hall effect by van der Pauw method are 9.36×1016 cm-3 and 299 cm2/V·s at 293K, respectively. The temperature dependence of the energy band gap of the AgGaSe2 obtained from the absorption spectra was well described by the Varshni's relation, Eg(T)=1.9501 eV-(8.79×10-4 eV/K)T2/(T＋250 K). The crystal field and the spin-orbit splitting energies for the valence band of the AgGaSe2have been estimated to be 0.2026 eV and 0.2165 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the Δso definitely exists in the Γ5 states of the valence band of the AgGaSe2. The three photocurrent peaks observed at 10 K are ascribed to the A1-, B1-, and C1-exciton peaks for n = 1. |
