LAUSR

Ultra-thin germanium-tin on insulator (GeSnOI) structure on Si substrate has been fabricated using the direct bonding and substrate etching techniques. This process involves the growth of GeSn layer on Ge (001) substrate followed by the deposition of ALD-Al2O3 on GeSn layer, the bonding of GeSn/Ge (001) substrate to a SiO2/Si substrate, and the removal of the Ge substrate. Using the bevel substrate etching technique, we prepared different GeSnOI structures, whose thicknesses gradually varied from 50 to 0 nm, in one sample. We investigated the thickness dependence of the material quality of the fabricated structure via micro-Raman spectroscopy; the strong Ge–Ge peaks are observed in a few nm thick GeSnOI structure, suggesting high quality of the fabricated GeSnOI structure and the enhancement of Raman intensity of the Ge–Ge peak in the ultra-thin GeSnOI structure of thickness less than 10 nm is attributed to the quantum size effect.