Atomically-coherent-coalescence of two growth-fronts in Ge stripes on insulator by rapid-melting lateral-crystallization

High-quality Ge-on-insulator (GOI) is a key structure for integrating high-speed transistors and optical- and spintronic-devices on Si-platform. Effects of coalescence of two growth-fronts on crystallinity of GOI-stripes during rapid-melting lateral-crystallization are investigated as a function of growth-distance. For long growth-distance (≥150 μm), grain-boundaries are generated in coalesced regions due to tilting growth-fronts (1-3°). On the other hand, for short distance (≤5 μm), lattice-structures coherently align without strains. Moreover, for intermediate distance (5-150 μm), lattice-structures of growth-fronts coherently align without any defects, though heterogeneous lattice-strains are locally induced due to slightly tilting growth-fronts (∼0.5°). Such atomically-coherentcoalescence for growth-distance <150 μm shows significant advantage of rapid-melting-crystallization over vapor and solid-phase techniques.