Disorder and compositional dependences in Urbach-Martienssen tails in amorphous (GeTe)(x)(Sb(2)Te(3))(1−x) alloys

This work focuses on the compositional dependences in parameters that govern the optical properties of (GeTe)(x)(Sb(2)Te(3))(1−x) amorphous alloys in the wide spectral range from above the phonons and to the inter-band electronic transitions. We studied the absorption edge fluctuations that are linked to the variations of the bandgap E(g), the width of Urbach-Martienssen tails E(U), the Tauc parameter B(1/2), and average halfwidth <FWHM> of Raman bands in amorphous (GeTe)(x)(Sb(2)Te(3))(1−x) alloys at various temperatures. Obtained results reveal the compositional trends in the influence of the disordering on the absorption processes in studied alloys.