In situ X-ray diffraction during stacking of InAs/GaAs(0 0 1) quantum dot layers and photoluminescence spectroscopy

Takahashi, Masamitsu; Kaizu, Toshiyuki*

The molecular beam epitaxial (MBE) growth of InAs/GaAs(001) quantum dots was investigated by grazing-incidence X-ray diffraction using a diffractometer integrated with an MBE apparatus. Use of synchrotron radiation and a two-dimensional X-ray detector enabled three-dimensional mapping of X-ray diffraction intensity at a rate of 10 s per frame. A series of X-ray diffraction images have revealed the evolution of the shape and internal strains of InAs quantum dots in the whole growth processes including the island formation and encapsulation with GaAs. The optical quality of InAs quantum dots was evaluated by photoluminescence spectra. It shows a clear correlation with structural properties measured by in situ X-ray diffraction.