Electronic excitation-enhanced crystallization of amorphous films

Summary form only given. The study of the interaction of ultrashort laser pulses with solids has raised some important questions concerning the nature of the transformations occurring at the material surface in the presence of very strong levels of electronic excitation. Even though the presence of electronic excitation-induced metastable transient phases has been demonstrated in several materials on irradiation with femtosecond laser pulses, the role of electronic excitation in permanent phase transitions is still not fully understood, and different nonthermal effects have been invoked to explain permanent structural changes induced in amorphous Si and Ge on nanosecond and picosecond laser pulse irradiation.