PHONON DRAG, CARRIER DIFFUSIVE THERMOELECTRIC POWER AND SEMICONDUCTING RESISTIVITY BEHAVIOR OF Zn NANOWIRES

Abstract

In this paper, we undertake a quantitative analysis of observed temperature-dependent thermoelectric power ðSÞ of 4 nm Zn/Vycor composite nanowires by developing a model Hamiltonian that incorporates scattering of acoustic phonons with impurities, grain boundaries, charge carriers and phonons. Mott expression is used to determine the carrier di®usive thermoelectric power ðS diff c Þ. The S diff c shows linear temperature dependence and the computed S diff c when subtracted from the experimental data is interpreted as phonon drag thermoelectric power ðS drag ph Þ. The model Hamiltonian within the relaxation time approximation sets the limitations of the scattering of acoustic phonons with impurities, grain boundaries, charge carriers and phonons for thermoelectric power in the nanowires. It is shown that for acoustic phonons the scattering and transport cross sections are proportional to fourth power of the phonon in the Rayleigh regime. The resultant thermoelectric powers is an artefact of various operating scattering mechanisms and are computed for the¯rst time to our knowledge for Zn nanowires consistent with the experimentally reported behavior. The semiconducting nature of resistivity Int. J. Nanosci. 2010.09:453-459. Downloaded from www.worldscientific.com by UNIVERSITY OF MICHIGAN on 02/20/15. For personal use only.is discussed with small polaron conduction (SPC) model which consistently retraces the temperature-dependent resistivity behavior of Zn/Vycor composite.