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

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 degrees C) molecular beam epitaxy 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 degrees C) and high (500 degrees C) temperatures, does not degrade the crystal quality any further. By promoting adatom down-climb, 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.

Automated summary

The role of post-growth cyclic annealing (PGCA) and subsequent regrowth in improving the crystal quality and surface morphology of (111)-oriented Ge epitaxial layers grown by low temperature molecular beam epitaxy is investigated. It is found that PGCA effectively suppresses planar defects in Ge(111) epilayers. Additionally, PGCA promotes adatom down-climb and heals the surface morphology, leading to further improvement upon Ge regrowth.