Grain boundary filtration by selective nucleation and solid phase epitaxy of Ge through planar constrictions

Abstract

We have proposed and experimentally demonstrated a grain boundary filtration technique for unseeded fabrication of single grain semiconductor films on amorphous substrates by using patterned P-doped amorphous Ge films with In-induced selective nucleation and solid phase epitaxy. The patterns consist of a small Ge island seed region including a deposited metal selective nucleation site, a narrow seed region, and a single grain region consisting of a main rectangular island. Transmission electron microscopy revealed lateral epitaxy initiated at the edge of the selective nucleation site and the grain selection process through the narrow seed selection region produced only one grain orientation at the entrance of the main island. Single grain regions as large as 100 μm2 with only a few low-angle boundaries were formed at 400 °C without spontaneous nucleation.