Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 64: GaN: Preparation and Characterization III
HL 64.5: Talk
Wednesday, March 28, 2012, 17:30–17:45, EW 202
Determination of indium content in semipolar GaInN multiple quantum well samples using XRD — •Heiko Bremers1, Holger Jönen1, Uwe Rossow1, Stefan Schwaiger2, Ferdinand Scholz2, and Andreas Hangleiter1 — 1TU Braunschweig, Institute of Applied Physics, Braunschweig — 2Universität Ulm, Institute of Optoelectronics, Ulm
X-ray diffraction is one of the most important tools to determine the structural properties of solids. In the III-nitrides it has been used very successfully to determine compositions of ternary layers in polar as well as in non-polar samples. In semipolar samples additional shear stresses result in a change of the angles between base vectors. In order to quantify these changes we have to rotate the tensors describing Hookes law to a new coordinate system S′. By using the fact that in growth direction the normal stress equals zero, one in principle is able to determine the composition.
For the example of (1122) semipolar samples we will discuss the difficulties in really determining the composition. The properties of this particular orientation can be achieved by a rotation around the m-axis by an angle of approximately 58.4∘. The rotation changes the base system S (x, y, z) from [2110], [0110], [0002] direction towards the new system S′ (x′, y′, z′) [1123], [0110], [2112] direction. Unfortunately there are no lattice planes available to directly measure the strain component in the new x-direction. We will discuss a way out of this dilemma by using relations between the old and new base system.