Ge-dependent morphological change in poly-SiGe formed by Ni-mediated crystallization

Low-temperature (≤550°C) Ni-mediated crystallization of amorphous SiGe (a-Si _1-x Ge _x (0≤x≤1)) layers on SiO ₂ films has been investigated. The morphology of crystallized SiGe strongly depended on the Ge fraction. For low Ge fractions (<20%), Ge-doping enhanced plane growth was observed, which resulted in strain-free poly-Si _0.8 Ge _0.2 films with large grains (18μm). On the other hand, dendrite growth was dominant for intermediate Ge fractions (40-60%). Directions and widths of dendrites became straight and narrow with decreasing annealing temperature. Very sharp needle-like crystals (width: 0.05μm, length: 10μm) were obtained at the optimized growth conditions (Ge fraction: 40%, annealing: 450°C, 20h). These new poly-SiGe films on insulator should be utilized for the advanced system-in-displays and novel devices such as one-dimensional quantum wires.