Spontaneous lateral alignment of In0.25Ga0.75As self-assembled quantum dots on (311)B GaAs grown by gas source molecular beam epitaxy

Spontaneous lateral alignment was observed in InGaAs quantum dots formed by self-assembly on (311)B GaAs by gas source molecular beam epitaxy. The alignment occurred in a direction inclined about 60° from the [011] direction on a (3-11) [(311)B] surface. A typical base diameter of the dots was about 120±10 nm. The heights varied from 3 to 13 nm as the nominal thickness of the InGaAs layer increased from 4 to 8 nm. The formation mechanism for the alignment is studied based on the growth thickness dependence of the dot structures. A photoluminescence linewidth of 24 meV was obtained from 9 nm high dots at 77 K, indicating the formation of a uniform dot structure.