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Temperature Dependence Of The Fundamental Band Gap In Hexagonal GaN

Published online by Cambridge University Press:  10 February 2011

H. Herr ,
V. Alex  and
J. Weber
H. Herr
Affiliation:
Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany weber@vaxff1.mpi-stuttgart.mpg.de
V. Alex
Affiliation:
Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany weber@vaxff1.mpi-stuttgart.mpg.de
J. Weber
Affiliation:
Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany weber@vaxff1.mpi-stuttgart.mpg.de
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Abstract

Photoluminescence spectra of hexagonal GaN were measured in the temperature range T= 2 – 1200 K. We identify the Free Exciton (FX) as the dominant recombination process in our high quality samples for temperatures above 200 K. From the line shape fit of the FX we determine the excitonic band gap shift with temperature. An analysis according to the empirical Varshni equation gives Eg (T)-Eg(0 K) = (-α T2)/(T + β), with α = (7.3 ± 0.3)·10−4 eV/K and β = (594 ± 54) K. We have detected significant differences in the band gap energy at low and higher temperatures for GaN layers grown on different substrate materials. Heating GaN above 1200 K leads to irreversible changes in the near band gap photoluminescence spectra.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 482 , 1997 , 719
Copyright
Copyright © Materials Research Society 1998

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