Regensburg 2002 – scientific programme

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SYME: Mechanical Properties of Thin Films

SYME 3: Mechanical Stresses and Plasticity

SYME 3.5: Talk

Tuesday, March 12, 2002, 12:30–12:45, H 4

Relaxation Processes in Te-Based Phase Change Materials Examined by Bulge Testing — •christian panofen¹, stefan ziegler¹, matthias wuttig¹, ralph spolenak^2,3, and walter brown³ — ¹I. Phys. Institut, RWTH-Aachen — ²Lehigh University, Bethlehem, Pa, USA — ³Agere Systems, Murray Hill, NJ, USA

The desired increase in storage density for optical data storage requires a continuous optimization of materials. Using a bulge tester we examine thin Ge₂Sb₂Te₅, Ge₄Sb₁Te₅ and AgInSbTe films allowing a precise determination of mechanical properties by a direct, temperature independent application of stress. With a density change of 5-10% from the amorphous to the crystalline phase substantial stresses build up in the material. Plastic deformations in the film (viscous flow) relieve these stresses. The viscosity of the amorphous film determined by viscous flow experiments allows to determine an activation barrier for diffusion. This diffusion barrier strongly influences the crystallization kinetics during the phase transition. We measured the elastic and plastic deformation of amorphous thin films at constant stress and temperature. Our experiments contribute to an atomistic understanding of the kinetcs of fast solid-solid phase transition.