DETERMINATION OF THE LATERAL PERIODICITY OF NANOMETER QUANTUM-DOT ARRAYS BY TRIPLE-CRYSTAL DIFFRACTOMETRY

The lateral periodicity of InAs quantum dot arrays in a GaAs matrix consisting of submonolayer InAs films grown by molecular beam epitaxy on a terraced (001) GaAs substrate was measured in the differential rocking curve by triple crystal diffractometry. The x-ray diffraction of the array is described in the frame 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 limits of the description assuming an ideal array are estimated using the Laue interference function. The lateral periodicity of the array along [100] is 11 nm compared with 10 nm obtained from the miscut of the sample. This ideal lateral periodicity extends along [100] over about 10 cells of the array corresponding to 0.1 mum.