Defects, Entropy, and Melting of Amorphous Silicon

Abstract

Structural relaxation of amorphous Si (a-Si) is thought to be fully controlled by annihilation of point defects quenched in during preparation. The density of defects in unrelaxed a-Si is estimated from a wide variety of published experimental data to amount to several atomic %. The enthalpic and entropic contributions of these defects to the excess Gibbs free energy difference of a-Si over c-Si is estimated. The variation in free energy due to defects may lead to afurther melting temperature depression of 40 - 200 K for unrelaxed a-Si in addition to the 200 K depression already present between c-Si and relaxed a-Si.