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.