A technique was reported that significantly reduced threading dislocations in Ge on Si hetero-epitaxy. Germanium was first grown on Si and etched to produce pits in the surface where threading dislocations terminated. Further processing left a layer of SiO2 only within etch pits. Subsequent selective epitaxial Ge growth results in coalescence above the SiO2. The SiO2 blocked the threading dislocations from propagating into the upper Ge epilayer. With annealed Ge films grown on Si, the said method reduced the defect density from 2.6 x 108 to 1.7 x 106/cm2, potentially making the layer suitable for electronic and photovoltaic devices.

Dislocation Reduction in Heteroepitaxial Ge on Si using SiO2 Lined Etch Pits and Epitaxial Lateral Overgrowth. D.Leonhardt, S.M.Han: Applied Physics Letters, 2011, 99[11], 111911