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Subpicosecond Time-Resolved Raman Studies of Nonequilibrium Excitations in Wurtzite GaN

Published online by Cambridge University Press:  10 February 2011

K. T. Tsen ,
R. P. Joshi ,
D. K. Ferry ,
A. Botchkarev ,
B. Sverdlov ,
A. Salvador  and
H. Morkoc
K. T. Tsen
Affiliation:
Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287
R. P. Joshi
Affiliation:
Department of Electrical Engineering, Odl Dominion University, Norfolk, VA 23529
D. K. Ferry
Affiliation:
Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287
A. Botchkarev
Affiliation:
Coordinated Science Laboratory, University of Illinois, Urbana, IL 61801
B. Sverdlov
Affiliation:
Coordinated Science Laboratory, University of Illinois, Urbana, IL 61801
A. Salvador
Affiliation:
Coordinated Science Laboratory, University of Illinois, Urbana, IL 61801
H. Morkoc
Affiliation:
Coordinated Science Laboratory, University of Illinois, Urbana, IL 61801
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Abstract

Non-equilibrium electron distributions as well as phonon dynamics in wurtzite GaN have been measured by subpicosecond time-resolved Raman spectroscopy. Our experimental results have demonstrated that for electron densities n ≥ 5 × l017cm−3, the non-equilibrium electron distributions in wurtzite GaN can be very well described by Fermi-Dirac distribution functions with the temperature of electrons substantially higher than that of the lattice. The population relaxation time of longitudinal optical phonons was directly measured to be τ ≅ 5 ± 1 ps at T = 25 K. The experimental results on the temperature dependence of the lifetime of longitudinal optical phonons suggest that the primary decay channels for these phonons are the decay into (1) one transverse optical phonon and one high energy, longitudinal or transverse acoustical phonons; and (2) one transverse optical phonon and one E2 phonon.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 449: Symposium N – III-V Nitrides , 1996 , 737
Copyright
Copyright © Materials Research Society 1997

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References

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