Nanocrystallization of amorphous germanium films observed with nanosecond temporal resolution

Using dynamic transmission electron microscopy we measure nucleation and growth rates during laser driven crystallization of amorphous germanium (a-Ge) films supported by silicon monoxide membranes. The films were crystallized using single 532 nm laser pulses at a fluence of similar to 128 mJ cm(-2). Devitrification processes initiate less than 20 ns after excitation and are complete within similar to 55 ns. The nucleation rate was estimated by tracking crystallite density as a function of time and reached a maximum of similar to 1.6 X 10(22) nuclei/cm(3) s. This study provides information on nanocrystallization phenomena in a-Ge, which is important for the implementation of nanostructured group IV semiconductors in optoelectronics devices. (C) 2010 American Institute of Physics. [doi:10.1063/1.3518069]