| 초록 |
To obtain the single crystal thin films, CdGa2Se4 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 630 ℃ and 420 ℃, respectively. 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). After the as-grown single crystal CdGa2Se4 thin films were annealed in Cd-, Se-, and Ga -atmospheres, the origin of point defects of single crystal CdGa2Se4 thin films has been investigated by PL at 10 K. The native defects of VCd, VSe, Cdint, and Seint obtained by PL measurements were classified as donors or acceptors. We concluded that the heat-treatment in the Cd-atmosphere converted single crystal CdGa2Se4 thin films to an optical p-type. Also, we confirmed that Ga in CdGa2Se4/GaAs did not form the native defects because Ga in single crystal CdGa2Se4 thin films existed in the form of stable bonds. |
