Improvement of crystal quality and surface morphology of Ge/Gd₂O₃/Si(111) epitaxial layers by cyclic annealing and regrowth

Abstract

The role of post-growth cyclic annealing (PGCA) and subsequent regrowth, on the improvement of crystal quality and surface morphology of (111)-oriented Ge epitaxial layers, grown by low temperature (300 C) molecular beam epitaxy (MBE) on epi-Gd2O3/Si(111) substrates, is reported. We demonstrate that PGCA is efficient in suppressing rotational twins, reflection microtwins and stacking faults, the predominant planar defect types in Ge(111) epilayers. Continuing Ge growth after PGCA, both at low (300 C) and high (500 C) temperatures, does not degrade the crystal quality any further. By promoting adatom downclimb, PGCA is observed to also heal the surface morphology, which is further improved on Ge re-growth. These results are promising for development of high-quality Ge(111) epitaxial layers for photonic and electronic applications.