Au induced crystallization and layer exchange in a-Si/Au thin film on glass below and above the eutectic temperature.

Au (metal) induced layer exchange and crystallization of amorphous Si ( a -Si) on corning glass (CG) in a -Si/Au/CG thin film specimen upon vacuum annealing (~ 10 − 8 mbar) is reported. The crystallization characteristics of these specimens at temperatures ranging on either side of the Au-Si eutectic temperature T e (Au-Si) are investigated. Our results shows that solid state diffusion assisted layer exchange of the a -Si and Au layer, followed by crystallization of a -Si into crystalline Si ( c -Si) occur at 350 °C (below the T e ). The upper limit to this crystallization mechanism was observed to be above the T e (Au-Si) and this continues till ~ 400 °C in the present study. Above this limit, the layer exchange phenomenon ceases and eutectic mixing reaction of Au-Si takes over to form diffusion limited crystalline aggregates of Si with different microstructural attributes. [ABSTRACT FROM AUTHOR]