Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: III-V semiconductors II
HL 33.8: Vortrag
Mittwoch, 27. Februar 2008, 16:15–16:30, EW 201
Strain fields in the vicinity of nanoindentions on (100) surfaces of GaAs — •Christian Röder1, Gert Irmer1, Michael Schaper2, Ralf Hammer3, and Manfred Jurisch3 — 1Institut für Theoretische Physik, TU Bergakademie Freiberg, Leipziger Straße 23, 09596 Freiberg, Germany — 2Institut für Werkstoffwissenschaft, TU Dresden, Helmholtzstraße 7, 01062 Dresden, Germany — 3Freiberger Compound Materials GmbH, Am Junger Löwe Schacht 5, 09599 Freiberg, Germany
We present results of micro-Raman and micro-photoluminescence (PL) investigations on undoped GaAs samples with Vickers indentations on (100) surfaces generated with low indentation loads down to 5 mN. Because of the slight indentation loads cracks did not occur. In the vicinity up to 10xD of such indentations with a diagonal length of D we observed a characteristic shift of the Raman LO phonon mode. Converting this shift we found a strain field pattern reflecting the crystal symmetry. Referring to the [011] and [0-11] directions the observed residual stress is different indicating various stress relaxation mechanisms. Furthermore the Raman spectra provide information about the crystallinity and stress induced defect density. It is assumed that GaAs is in an amorphous state below the indenter top. PL measurements were performed at 293 K with the special emphasis on the study of the strain induced splitting between the heavy and light hole valence bands. The observed splitting of the PL signal is discussed in correlation to theoretical stress models and the Raman results.