Title

Analyzing Residual Stress in Bilayer Chalcogenide Ge2Se3/SnTe Films

Document Type

Article

Publication Date

10-30-2009

Abstract

Chalcogenide thin film stacks of polycrystalline SnTe and amorphous Ge2Se3 are analyzed for residual stress using X-ray diffraction. The as-deposited film stacks are annealed at different temperatures and the thermal dependence of stress is investigated. Stress evaluations are performed by employing the sin2 ψ technique using a 2D area detector system. As-deposited samples are found to be compressively stressed and exhibit increasingly tensile thermal stress with increasing annealing temperature. Onset of crystallization of the bottom Ge2Se3 layer is indicated by a sharp drop in the stress level in the 270°C–360°C temperature range, due to volume shrinkage associated with the crystallization. Diffraction patterns of samples annealed at different temperatures indicate compositional changes that are attributed to inter-diffusion of ions between the two layers. The XRD profiles of samples annealed at 360°C and 450°C indicate the formation of a Ge2Se3–SnTe solid solution. It is suggested that both, residual stress and temperature dependent compositional changes affect the measured d spacings.