Reverse mass transport during capping of In0.5Ga0.5As/GaAs quantum dots

The rates of indium mass transport between the wetting layer, the quantum dots, and the capping layer are derived from the indium distributions probed by cross-sectional scanning tunneling microscopy of the In0.5Ga0.5As/GaAs quantum dot system. During capping, a lateral back-segregation from the quantum dots toward the wetting layer is found, reversing the Stranski-Krastanov growth mode during quantum dot formation. This lateral back-segregation critically affects the resulting indium distribution in the wetting layer, the apparent segregation coefficients as well as the quantum dot shape. Furthermore, the strain effect on the segregation coefficient is quantified.