Heteroepitaxy for GaAs on Nanopatterned Si (001)

An almost defect pit-free GaAs is achieved using nanopatterned Si (001). The largest nanopattern with an aspect ratio of 4.18 and the narrowest strip of around 55 nm in width are adopted in this letter. The threading dislocations, beginning from the GaAs-Si interface and moving along the facet plane to the sidewall, are interrupted within the initial epitaxial layer. With the aspect ratio increasing from 0.44 to 2.04, the etching defect pit density can be decreased from around 5.0 × 10⁹ cm^-2 to almost zero. The improvement in material quality is verified by transmission electron microscopy, photoluminescence, and X-ray diffraction studies.