′�?, that has a frequency of 295 cm−1, is attributed for the stretching vibration of Ga–Se bonds. The 2-phonon absorption with the 295 cm−1 phonon corresponds towards the crystal IR absorption edge, rather than the residual absorption peak. Density useful idea computations show the residual absorption with the BGSe crystal https://franciscozttrm.eedblog.com/32896049/baga4se7-crystal-fundamentals-explained