The temperature-dependence of carrier mobility is not a reliable indicator of the dominant scattering mechanism

TL;DR

This paper critically examines the common practice of using temperature dependence of carrier mobility to identify dominant scattering mechanisms, revealing that phonon frequencies, not scattering types, primarily influence this dependence.

Contribution

The study demonstrates that temperature dependence of mobility is not a reliable indicator of scattering mechanisms, emphasizing the role of phonon frequencies in mobility behavior.

Findings

No correlation between scattering mechanisms and mobility temperature trends.

Phonon frequencies drive the temperature dependence of mobility.

T^{-1.5} dependence is not indicative of deformation potential scattering.

Abstract

The temperature dependence of experimental charge carrier mobility is commonly used as a predictor of the dominant carrier scattering mechanism in semiconductors, particularly in thermoelectric applications. In this work, we critically evaluate whether this practice is well founded. A review of 47 state-of-the-art mobility calculations reveals no correlation between the major scattering mechanism and the temperature trend of mobility. Instead, we demonstrate that the phonon frequencies are the prevailing driving forces behind the temperature dependence and can cause it to vary between $T^{-1}$ to $T^{-3}$ even for an idealised material. To demonstrate this, we calculate the mobility of 23,000 materials and review their temperature dependence, including separating the contributions from deformation, polar, and impurity scattering mechanisms. We conclusively demonstrate that a temperature dependence of $T^{-1.5}$ is not a reliable indicator of deformation potential scattering. Our work highlights the potential pitfalls of predicting the major scattering type based on the experimental mobility temperature trend alone.