Defect reduction of selective Ge epitaxy in trenches on Si(001) substrates using aspect ratio trapping

Defect-free germanium has been demonstrated in SiO2 trenches on silicon via Aspect Ratio Trapping, whereby defects arising from lattice mismatch are trapped by laterally confining sidewalls. Results were achieved through a combination of conventional photolithography, reactive ion etching of SiO2, and selective growth of Ge as thin as 450 nm. Full trapping of dislocations originating at the Ge/Si interface has been demonstrated for trenches up to 400 nm wide without the additional formation of defects at the sidewalls. This approach shows great promise for the integration of Ge and/or III-V materials, sufficiently large for key device applications, onto silicon substrates.