Multilevel reversible laser-induced phase transitions in GeTe thin films

Abstract

This paper presents the results of a study on the structural properties and dynamics of conductivity of thin (d ∼ 100 nm) films of germanium telluride depending on the phase states reversibly switched by nanosecond pulsed laser radiation with a «top hat» beam profile. It was determined that the threshold of laser radiation energy density at which the phase transition in GeTe thin films from the amorphous to crystalline state is in the range of E = 7.5 ÷ 47.6 mJ/cm2, and the threshold for the reverse transition from the crystalline to amorphous state starts from 47.6 mJ/cm2 and is observed up to 90 mJ/cm2 with no visible damage caused by the ablation. The full time of conductivity change associated with the phase transition between the amorphous and crystalline phases is τCA = 20.2 ns, while for the reverse crystalline to amorphous transition, the conductivity full change time it makes τAC = 52 ns.