Structural characterization of nanostructures grown by Ni metal induced lateral crystallization of amorphous-Si

The nickel metal induced lateral crystallization of amorphous silicon is studied by transmission electron microscopy in the range of temperatures from 413 to 521 degrees C. The structural characteristics of the whiskers grown at 413 degrees C are compared to the grains grown at 600 degrees C, where both Metal Induced Lateral Crystallization (MILC) and Solid Phase Crystallization (SPC) are involved. At 413 degrees C, long whiskers are formed at any crystallographic direction almost free of defects. In contrary, whiskers grown by MILC around 600 degrees C are crystallized along the < 111 > directions. These differences are attributed to the low crystallization rate and suppression of the SPC process. The activation energy of the pure MILC was measured in the order of 2 eV. The effect of Ni on the crystallization rate is studied by in-situ heating experiments inside the microscope. The role of contamination that can inhibit MILC is discussed. The cases of MILC process under limited Ni and unlimited Ni source were studied and compared to in-situ annealing experiments. The crystallization rate is strongly influenced by the neighbouring Ni sources; this long-range interaction is attributed to the requirement of a critical Ni concentration in amorphous silicon before the initiation of the MILC process. The long-range interaction can enhance crystallization along a certain direction. The transition from MILC to SPC and the change of the crystallization mode due to the lack of Ni are discussed. The beneficial effect of long annealing at 413 degrees C is also discussed. (C) 2016 AIP Publishing LLC.