Pd2Si-assisted crystallization of amorphous silicon thin films at low temperature

An ultrathin palladium layer was deposited on top of amorphous silicon films and the crystallization enhancement of the underlying amorphous silicon films was observed. The crystallization temperature was lowered down to 350 degrees C while that of intrinsic silicon films is around 600 degrees C. The degree of enhancement was found to be dependent on the thickness of the palladium layer as well as the annealing temperature. From the microstructure analysis, the formation of Pd2Si precipitates in the amorphous silicon was observed at the initial stage of crystallization and after further annealing, the crystallization of amorphous silicon was observed with the simultaneous split of the preformed Pd2Si precipitates into many small pieces. The mechanism of this abnormal phenomenon is discussed with the theory of epitaxial growth. (C) 1999 American Institute of Physics. [S0021-8979(99)06210-6].