| 초록 |
Single crystal CdGa2Se4 layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at 420 ℃ with the hot wall epitaxy (HWE) system by evaporating the polycrystal source of CdGa2Se4 at 630 ℃prepared from horizontal electric furnace. 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 CdGa2Se4 thin films measured with Hall effect by van der Pauw method are 8.27× 1017 cm-3, 345 cm 2/V·s at 293K, respectively. The photocurrent and the absorption spectra of CdGa2Se4 /SI(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10K. The temperature dependence of the energy band gap of the CdGa2Se4 obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 2.6400 eV - (7.721 × 10-4 eV/K)T2/(T + 399 K). Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(Δcr) and the spin-orbit splitting energy(Δso) for the valence band of the CdGa2Se4 have been estimated to be 106.5 meV and 418.9 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the A1-, B1-, and C11-exciton peaks. |
