Method and apparatus for crystallization semiconductor thin film on a substrate material

In a process for crystallization of thin semiconductor layers on a substrate material, a melt with a temperature profile is produced in the surface layer of the substrate. The temperature profile has an ''undercooled'' region essentially symmetrical in relation to its centre with a lateral dimension equal to the thickness of the melt. The melt in the surface layer of the substrate material is preferably produced by irradiation with a laser beam in the TEM01 or TEM01* oscillating mode. The process is particularly suitable for crystallization of single crystal silicon regions on silicon-on-insulator (SOI) substrates.