Diffusion and crystallization mechanisms of Ge∕Au bilayer media for write-once optical disk

Abstract

Ge ∕ Au bilayer thin films were fabricated by magnetron sputtering method, the temperature dependence of resistance from room temperature to 500°C and concentration depth profiles are measured. From the temperature dependence of resistance measurement, we found two phase change phenomena which occurred at 175 and 360°C. The element concentration depth profiles of the as-deposited and recorded region indicate that the Au–Ge alloy is initially formed at the Ge∕Au interface. The dominant diffusion element is Au atom and the diffusion path is from Au layer to Ge layer. The optimum simulated bit error rate value is about 1.4×0−6 at 9.0mW under two time high definition digital versatile disk (HD DVD) recording speed. The dynamic tests show that this Ge∕Au bilayer films can be applied to one to two times HD DVD-R.