Controlling the size of InAs quantum dots on Si1−xGex/Si(0 0 1) by metalorganic vapor-phase epitaxy

The formation of III–V InAs quantum dots (QDs) on group-IV Si1−xGex/Si(0 0 1) was investigated by metalorganic vapor-phase epitaxy. Two types of QDs, round-shaped QDs and giant QDs elongated in the [1 1 0] or [1,−1,0] direction, were observed in a growth condition of low V/III ratios. An increase in the V/III ratio and AsH3 preflow during the cooling process was found to suppress the formation of giant QDs. It was considered that replacing the H-stabilized SiGe surface with the As-stabilized surface was necessary for increasing the QD nucleation. The size and density of InAs QDs on SiGe were controllable as well as that on III–V semiconductor buffer layers, and InAs QDs with a density as high as 5 × 1010 cm−2 were obtained.