| 초록 |
A stoichiometric mixture of evaporating materials for CuAlSe2 single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, CuAlSe2 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were 680℃ and 410℃, respectively. 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 CuAlSe2 single crystal thin films measured with Hall effect by van der Pauw method are 9.24×1016 cm-3 and 295 cm2/V․s at 293K, respectively. The temperature dependence of the energy band gap of the CuAlSe2 obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 2.8382 eV - (8.86 × 10-4 eV/K)T2/(T + 155K). After the as-grown CuAlSe2 single crystal thin films was annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of CuAlSe2 single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of VCd, VSe, Cdint, and Seint obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Cu-atmosphere converted CuAlSe2 single crystal thin films to an optical n-type. Also, we confirmed that Al in CuAlSe2/GaAs did not form the native defects because Al in CuAlSe2 single crystal thin films existed in the form of stable bonds. |
