Seebeck effect in dilute two-dimensional electron systems: temperature dependencies of diffusion and phonon-drag thermoelectric powers

TL;DR

This paper provides a theoretical analysis of the low-temperature Seebeck effect in dilute two-dimensional semiconductors, revealing complex temperature dependencies of thermoelectric powers beyond simple power-laws.

Contribution

It introduces a detailed theoretical model considering screening effects and solves the Boltzmann equation without relaxation time approximation to analyze thermoelectric powers.

Findings

$|S_d|/T$ decreases for $T \gtrsim 0.1 \epsilon_F$

$|S_g|$ peaks between Bloch-Gr"uneisen temperature and Fermi energy

Thermoelectric powers do not follow simple power-law temperature dependencies

Abstract

Considering screeening of electron scattering interactions in terms of the finite-temperature STLS theory and solving the linearized Boltzmann equation (with no appeal to a relaxation time approximation), we present a theoretical analysis of the low-temperature Seebeck effect in two-dimensional semiconductors with dilute electron densities. We find that the temperature ($T$) dependencies of the diffusion and phonon-drag thermoelectric powers ($S_d$ and $S_g$) can no longer be described by the conventional simple power-laws. As temperature increases, $|S_d|/T$ decreases when $T\gtrsim 0.1 \epsilon_F$ ($\epsilon_F$ is the Fermi energy), while $|S_g|$ first increases and then falls, resulting a peak located at a temperature between Bloch-Gr\"uneisen temperature and $\epsilon_F$.