Determination of the crystallographic orientation of CuInSe2 thin films by Raman and infrared spectroscopy

Abstract
Polarized Raman spectra were measured at room temperature from the (001)- and (112)-oriented CuInSe2 heteroepitaxial layers grown on (001)- and (111)-oriented Si substrates. The analysis of the results proved the expected orientation and good crystalline quality of the (001) layers. No special crystallographic direction was identified unambiguously on the (112) plane. Similar behavior was confirmed by infrared transmission spectroscopy. This can be explained by the existence of rotational twins, which have been observed by x-ray diffraction.