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HL: Halbleiterphysik
HL 48: Postdeadline III
HL 48.1: Vortrag
Freitag, 26. März 1999, 13:30–13:45, H3
Depth Resolved X-Ray Investigations of the Strain State in Buried Quantum Wires — •Nora Darowski1, Jörg Grenzer1, Alex Ulyanenkov1, Ullrich Pietsch1, and Alfred Forchel2 — 1Institut für Physik, Universität Potsdam, Germany — 2Institut für Technische Physik, Universität Würzburg, Germany
Grazing incidence diffraction (GID) of free-standing and buried
surface gratings of a conventional quantum well laser structure was
used to analyse the the strain distribution inside the grating
structure depth-resolved. The penetration depth of the probing x-rays
can be varied by changing the angle of incidence with respect to the
sample surface.
The influence of strain can be seen in the longitudinal scan,
which is sensitive to both, strain and shape of the grating.
Strain shifts the envelope of the grating peak intensities with respect
to the substrate peak.
A completely different behavior is found in case of the strain insensitive
transverse scan. A abscence of grating peaks at this type of scan but their appearance
at the longitudinal scan is a clear indication for the creation of a
periodic strain modulation in the overgrown layer, induced by the buried
initial grating.
A detailed analysis of the geometric parameters and the strain profil
of the structure is carried out by calculations based on the distorted
wave Born approximation for grazing incidence geometry in combination
with FEM.