STRAIN AND BOND DISTORTIONS IN SEMICONDUCTOR THIN-ALLOY FILMS

Joseph C. Woicik

National Institute of Standards and Technology, Gaithersburg MD 20899, USA

When external forces act on a material, its macroscopic deformations are accurately described by the theory of elasticity. This talk will examine how these macroscopic strains translate into microscopic, atomic-scale structural distortions. Specifically, we will examine the structure of semiconductor thin-alloy films grown coherently on lattice-mismatched substrates. X-ray diffraction, extended x-ray absorption fine structure, diffraction anomalous fine structure, and x-ray standing wave spectroscopies will be described and used to determine how the lattice spacing and local atomic bonding change with strain. These structural results are interpreted using valence-force field calculations and other theoretical models.