ABSTRACT
Self-assembled quantum dots in semiconductor heterostructures are of great interest, because of their discrete atomlike energy levels, good optical properties and promising device applications such as quantum dot laser and infrared photo-detector. [1] In lattice-mismatched system such as (In, Ga)As/GaAs, the self-assembled quantum dots can be achieved by the Stranski-Krastanov (S-K) growth mode. [2] To control the growth mode, it is important to understand a relation between the structure of the 2D wetting layer and the transition to 3D growth. The 2D wetting layer varies as a function of InAs coverage and growth temperature. [3] The wetting layers initially show three-fold (x3) patterns in the [-110] azimuth. It was reported that this indicates a formation of an (In, Ga)As-alloy phase. [3-5] With increasing the InAs coverage, this alloy phase is followed by an InAs phase with the (2x4) surface reconstruction. The various possible surface conditions, which depend on growth conditions, play a key role in the S-K growth mode.
