A transverse acoustic phonon mode in gallium arsenide has energy ( ).

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Lattice dynamics and thermal properties of solids · Lattice dynamics and thermal properties of solids

Solid State Physics, Ch Phonons: quantisation, occupation and inelastic scattering

Problem

A transverse acoustic phonon mode in gallium arsenide has energy

\hbar\omega=6.0\,\mathrm{meV}

(

1.45\,\mathrm{THz}

). ((a)) Calculate the mean occupation number

\langle n\rangle

of this mode at

T=350\,\mathrm{K}

. ((b)) Calculate the classical limit

k_BT/\hbar\omega

at the same temperature and state, with a reason, whether the mode is close to classical behaviour.

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