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Surface phonon polariton modes of wurtzite structure Al x Ga 1– x N thin film
Author(s) -
Zhang L.,
Shi J.J.
Publication year - 2009
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.200844023
Subject(s) - wurtzite crystal structure , polariton , phonon , thin film , condensed matter physics , surface phonon , materials science , optics , physics , nanotechnology , diffraction
The polar phonon polariton modes in a wurtzite thin film structure are theoretically investigated in the present paper. It is confirmed that there are two types of phonon polariton modes, i.e. the surface phonon polariton (SPP) modes and the confined phonon polariton (CPP) modes in wurtzite thin film systems. The frequency ranges of the SPP and CPP modes are discussed in detail. The dispersive equation of the SPP modes is also deduced. Numerical calculations on Al x Ga 1– x N thin film structures reveal that, for a given free wave number k t in the x ‐direction, there are two branches of SPP modes in general. The Al concentration x of Al x Ga 1– x N materials and the thickness d of the wurtzite thin film have an important influence on the dispersive properties of the polariton modes, especially as the thickness d is small. Our calculated results are completely consistent with the recent experimental observation in Al x Ga 1– x N thin film systems. We confirm that the SPP modes observed are the low‐frequency branches of SPP modes. Furthermore, the frequency values of the high‐frequency branches of SPP modes are explicitly given, and a possible method for observing these high‐frequency SPP modes is also brought forward. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)