The mechanism of texture formation during crystallization process of Ge2Sb2Te5 thin films

Abstract

In this work, we determined the grain growth mode and texture formation process experimentally and theoretically in crystallization process of Ge2Sb2Te5 thin films, which were prepared by ion beam sputtering using Ge2Sb2Te5 alloy target. Experiment results demonstrated that crystalline grains had a trend of island growth during annealing, the texture components of cube {100}<001> and rotation cube {100}<011> are present in 250 °C annealed thin films, and {0001} basal texture component was produced in 400 °C annealed thin films. Theoretical analysis proved the mechanism and driving forces of grain growth and cubic texture formation: grains gathered in the basal surface as island because of large lattice mismatch, meanwhile, the preferred orientation of thin films was triggered by the minimization of lattice mismatch strain energy. The calculation results were in conformance with the experimental results. Researches about grain growth mode and texture formation of Ge2Sb2Te5 thin films may provide an advice to increase the crystallization rate of phase change material.