Annealing induced transition of flat strained InGaAs epilayers into three-dimensional islands.

We report arrays of self-assembled quantum dots through roughening transition of strained but atomically flat layers into three-dimensional (3D) islands. Atomically flat two-dimensional InGaAs epilayers were grown on GaAs(001) substrates below 360 °C. When heated higher than 420 °C, they were observed to undergo roughening transitions. The morphology, height, and width of the resultant 3D features were found to be a strong function of the annealing time and temperature. Furthermore, at a particular set of parameters, dot chains were observed. The strain field of the flat layer seemed uniform in the roughening stage, but appeared to induce anisotropic diffusion at the subsequent growth stage. [ABSTRACT FROM AUTHOR]