Growth and characterization of CuAlSe2(1 1 2)/GaAs(1 0 0) heteroepitaxial layers grown by hot wall epitaxy method

The CuAlSe2(1 1 2)/GaAs(1 0 0) heteroepitaxial layers were grown by the hot wall epitaxy (HWE) method. From the measurements of the Laue patterns and the double crystal X-ray diffraction, the CuAlSe2 epilayer was confirmed to be the epitaxially grown layer along the 〈1 1 2〉 direction onto a GaAs (1 0 0) substrate. The Hall mobility and carrier density of the CuAlSe2 epilayer at 293 K were estimated to be 295 cm2/V s and 9.24×1016 cm−3, respectively. This mobility is approximately one order higher than the reported value. From the temperature dependence of the Hall mobility, the scattering at a high-temperature range was mainly due to the acoustic mode of lattice vibration. The scattering at a low temperature was the most pronounced range due to the impurity effect. From the low-temperature photoluminescence experiment, we observed the sharp and intensive free-exciton peak at 2.7918 eV. Also, this peak existed far more in the short-wavelength region than 2.739 eV of free exciton measured from the epilayer grown by the metalorganic chemical vapor deposition (MOCVD). Consequently, these facts indicate that the CuAlSe2 epilayers grown by the HWE method are higher quality crystals than those grown by MOCVD or other methods.