Phonon-drag effects on thermoelectric power

Abstract

We carry out a calculation of the phonon-drag contribution Sg to the thermoelectric power of bulk semiconductors and quantum well structures for the first time using the balance equation transport theory extended to the weakly nonuniform systems. Introducing wavevector and phononmode dependent relaxation times due to phonon-phonon interactions, the formula obtained can be used not only at low temperatures where the phonon mean free path is determined by boundary scattering, but also at high temperatures. In the linear transport limit, Sg is equivalent to the result obtained from the Boltzmann equation with a relaxation time approximation. The theory is applied to experiments and agreement is found between the theoretical predictions and experimental results. The role of hot-electron effects in Sg is discussed. The importance of the contribution of Sg to thermoelectric power in the hot-electron transport condition is emphasized. 72.15.Jf, 72.20.Pa, 72.20.Ht, 72.10.Bg

Size‐Dependent Transport and Thermoelectric Properties of Individual Polycrystalline Bismuth Nanowires

“…Consequently, , should correspond to an S d value of 0. The observed nonzero value of S is reflective of two facts: 1) S g , the phonon-drag component of S, has not been taken into account, which could be significant at this temperature, [46] and 2) S m , the thermoelectric power of Pt/Ti electrodes used to establish the thermocouple with Bi nanowires, has not been considered. The Pt/Ti electrodes are not expected to contribute to the EFE due to their extremely small screening lengths, [44] but they might cause a uniform shift -S m in S at all V g .…”

Flexible Thermoelectric Materials and Generators: Challenges and Innovations

“…They found that smaller Te dots exhibit higher S than larger Te dots, as revealed in Figure h. This is because smaller Te dots (≈2 nm) can prevent inefficient phonon scattering in the composites, which would otherwise lower S according to the phonon‐drag theory . With a tuned doping level for enhancing σ, a peak S 2 σ of ≈100 µW m −1 K −2 has been achieved at room temperature …”

Magneto-Seebeck effect inRFeAsO(R=rareearth) compounds: Probing the magnon drag scenario

“…Since we are interested in deriving general properties, we do not solve the problem using a full hydrodynamical approach where a complete analysis of the momentum transfer between electrons, phonons, and magnons is taken into account. This kind of approach has been used for phonons with moderate success [28], but it is out of the scope of the present work. Instead, we follow a more intuitive approach inspired by the analysis of the magnon drag Peltier effect carried out for a ferromagnetic (FM) chain [29] and spectacularly confirmed for real cases [30].…”