Grazing incidence x-ray diffraction measurements of columnar InAs/GaAs quantum dot structures

Abstract

The lattice constant distribution inside a columnar InAs/GaAs quantum dot (QD) and its crystal orientation dependence were evaluated by grazing incidence X-ray diffraction (GIXD) measurement. The QDs were grown by stacking Stranski-Krastanow (SK)-type InAs QDs directly in the growth direction with very thin GaAs interval layers. We evaluated the dependence of the in-plane lattice constant on QD height by GIXD measurement using equipment available for laboratories. We found that the lattice constants at the top and bottom of the QDs were almost the same when the height and diameter of the QDs were almost equal. As the number of stacks was increased to grow high QDs, the lattice constant at the QD top became larger in the [11̄0] direction than in the [11̄0] direction, but this relationship was reversed at the bottom. We consider that GIXD measurement with compact equipment will contribute to the swift and efficient development of QD devices. © 2010 The Japan Society of Applied Physics.