Phonon excitations and thermodynamic properties of cubic III nitrides

Talwar, D. N.
March 2002
Applied Physics Letters;3/4/2002, Vol. 80 Issue 9, p1553
Academic Journal
A comprehensive study of phonon excitation and thermodynamic properties of cubic GaN and A1N is reported using a rigid-ion model (RIM) in the quasiharmonic approximation. The data on elastic constants and phonon modes at critical points at ambient and high pressures have allowed us to optimize RIM parameters to obtain accurate values of phonon dispersions, one-phonon density of states, mode Grüneisen parameters γ(q), specific heat C[sub v](T), and thermal expansion α(T) coefficients. Despite the small softening of TA modes in GaN and A1N, the variations of thermal expansion coefficients are seen much like that of C[sub v](T), and unlike other III-V compounds it exhibits no negative values at lower temperatures.


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    © 2003 American Institute of Physics.


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