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Optically induced strain relaxation in anisotropically strained M ‐plane GaN films
Author(s) -
Flissikowski T.,
Brandt O.,
Misra P.,
Grahn H. T.
Publication year - 2008
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200778651
Subject(s) - photoluminescence , raman spectroscopy , relaxation (psychology) , strain (injury) , materials science , spectroscopy , anisotropy , optoelectronics , condensed matter physics , molecular physics , optics , chemistry , physics , medicine , psychology , social psychology , quantum mechanics
We study the anisotropic in‐plane strain in M ‐plane GaN films by photoreflectance, photoluminescence, Raman, and time‐resolved pump‐and‐probe spectroscopy. We find that a highly strained film partially relaxes, if it is pumped by an intense optical pulse. The strain relaxation can be observed by a shift of the E 2 ‐Raman line to lower energies and by a shift of the fundamental interband transition energies in the photoreflectance spectra. The photoluminescence intensity of the exposed areas is significantly reduced as compared to the one for areas, which have not been exposed to the intense optical pulse. This suggests that the strain relaxation is connected to the introduction of defects, which can act as non‐radiative recombination centers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)