In-situ stress analysis for aluminum-induced crystallization of germanium as a function of anneal ramp time

The effects of annealing ramp-rate during aluminum-induced crystallization were observed in-situ, and play a vital role in initial grain formation and termination, respectively. The absolute Al and Ge thickness, as well as the ratio between them, were varied in an attempt to minimize both the initial stress in the film as well as the stress induced while the anneal progressed. It was found that bilayer films with 300 nm of Al and 200 nm of Ge, annealed at a ramp-up rate of 1 °C/s and a ramp-down rate of 0.1 °C/s, produced the largest grains (~90 μm) compared to samples with either thinner Al layers, thicker Ge layers, or different ramp-up or ramp-down rates that were also analyzed in this study.