Anisotropic Strain State Of The [1(1)Over-Bar00] Gan Quantum Dots And Quantum Wires

The strain state of the [1 (1) over bar 00] GaN quantum dots and quantum wires has been studied by a combination of multiwavelength anomalous diffraction and diffraction anomalous fine structure under grazing incidence. The three components of the anisotropic deformation have been independently determined. On one hand, a weak residual strain state along the c-axis, similar for quantum dots and quantum wires, is found. On the other hand, along the [11 (2) over tilde0] direction, quantum wires appear to be more relaxed than quantum dots. Based on high resolution transmission electron microscopy, this is assigned to elastic strain relaxation of GaN governed by either misfit dislocation formation or three-dimensional islanding, depending on the anisotropic strain state of the [1 (1) over bar 00] AlN buffer layer. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2979324]