Defect-free Ge was demonstrated in SiO2 trenches on Si via aspect ratio trapping, whereby defects arising from lattice mismatch were 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 450nm. Full trapping of dislocations originating at the Ge/Si interface was demonstrated for trenches up to 400nm wide without the additional formation of defects at the side-walls. This approach showed great promise for the integration of Ge and/or III-V materials, sufficiently large for key device applications, onto Si substrates.

Defect Reduction of Selective Ge Epitaxy in Trenches on Si(001) Substrates using Aspect Ratio Trapping. J.S.Park, J.Bai, M.Curtin, B.Adekore, M.Carroll, A.Lochtefeld: Applied Physics Letters, 2007, 90[5], 052113