Metal-catalyzed crystallization of amorphous Ge (a-Ge) was investigated in order to provide experimental evidence that this phenomenon was a defect-mediated process. Positron lifetime measurements were carried out on as-grown and annealed Al/a-Ge multilayers, in order to identify unambiguously the type of defects. Substantial positron trapping occurred at interfacial voids in the as-grown specimens. Annealing at 450 to 533K resulted in rapid interdiffusion of the layers, leading to the formation of crystalline precipitates of Ge in the Al matrix. Direct evidence was provided that the rapid transport and growth of crystalline Ge precipitates was aided by the transport of defects. These defects were identified to be 2- or 3-vacancy clusters.

Role of Defects in Metal Mediated Crystallization in Al/a-Ge Multilayers. G.Raghavan, R.Rajaraman: Physical Review B, 2003, 68[1], 012104 (4pp)