Selective growth of Ge on Si(100) through vias of SiO2 nanotemplate using solid source molecular beam epitaxy

Abstract

We demonstrate that Ge can be selectively grown on Si(100) through openings in a SiO2 nanotemplate by solid source molecular beam epitaxy. The selectivity relies on the thermal instability of GeO and SiO near 650 °C. Ge islands grow in the template windows and coalesce on top of the template, forming an epitaxial lateral overgrowth (ELO) layer. Cross-sectional transmission electron microscopy images show that the Ge seeds and the ELO layer are free of threading dislocations. Only stacking faults are generated but terminate within 70 nm of the Ge–Si interface, while twins along {111} planes are observed in the ELO layer. The threading-dislocation-free Ge seeds and ELO layer are attributed to epitaxial necking as well as Ge–Si intermixing at the interface.