Hypersound absorption of acoustic phonons in a degenerate carbon nanotube

Abstract

Short-wave sound absorption propagating along the axis of a semiconductor superlattice by electrons of the lowest miniband in a non-quantised electric field is investigated theoretically. The mechanism of the attenuation of phonons is due to Landau damping. The relationship discovered for the absorption coefficient r = T(E) s essentially different from that for homogeneous materials, and, additionally the threshold field at which the absorption switches over to amplification depends on the superlattice parameters and the length of the sound wave. The more important difference between short-wave sound amplification by a superlattice and amplification in the homogeneous materials is the possibility of finding a field E* such that -r( *) 2 r( E*). This situation allows in principle the use of a superlattice as a hypersound generator similar to a generator of long-wave sound. The above generator is impossible to construct in the case of homogeneous semiconductors