Measurement of the Lateral Periodicity of a Quantum Dot Array by Triple Crystal Diffractometry

Abstract

AbstractThe lateral periodicity of an InAs quantum dot array in a GaAs matrix is measured in the differential rocking curve by triple crystal diffractometry. The quantum dot array was grown by molecular beam epitaxy of submonolayer InAs films on a terraced (001) GaAs substrate. The x-ray diffraction of the array is described in the limits of the kinematical theory. Both the changes in the scattering factor and the tetragonal deformations due to the InAs quantum dots are taken into account. The lateral periodicity of the array along [100] is 8–11nm dependent on the position of the measured region compared with an average of 10nm obtained from the miscut of the sample. In addition the vertical periodicity of the array is measured by comparison of the double crystal rocking curve with the corresponding simulation in the dynamical approximation. The vertical period of the array along [001] is 26.5nm. The coverage of the submonolayer InAs films estimated from the same measurement is 0.4. The absence of plastic relaxation is confirmed by x-ray topography.