Structural Changes Caused by Quenching of InAs/GaAs(001) Quantum Dots

Self-assembled InAs/GaAs(001) quantum dot structures before and after quenching were investigated by in situ X-ray diffraction to assess the effects of quenching. Before quenching, quantums dots were uniform in size so that the shape and internal lattice constant distribution of a quantum dot were quantitatively determined on the basis of three-dimensional X-ray intensity mapping. X-ray measurements after quenching revealed that the quantum dot size showed a bimodal distribution as a result of the proliferation of dislocated islands during quenching. A formula to describe the X-ray diffraction from dislocated islands with a large size distribution is presented. The cooling rate between 20 and 40 K/min was found to have little effect on the structures of quenched quantum dots.