Investigation of defect states in the amorphous phase of phase change alloys GeTe and Ge₂Sb₂Te₅

Abstract

Abstract In amorphous materials localized states within the band gap govern the electronic transport properties. This work presents the first measurement of the density of states within the band gap of amorphous phase change alloys using modulated photo current experiments. Modulated photo current measurements performed on a‐Ge 50 Te 50 and a‐Ge 2 Sb 2 Te 5 show that the defect state density of both compositions is quite similar consisting of a pronounced valence band tail and at least two defect states (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)