Electron–Hole Scattering Limited Transport of Dirac Fermions in a Topological Insulator

Abstract

We have experimentally investigated the effect of electron temperature on transport in the two-dimensional Dirac surface states of the three-dimensional topological insulator HgTe. We have found that around the minimal conductivity point, where both electrons and holes are present, heating the carriers with a DC current results in a nonmonotonic differential resistance of narrow channels. We have shown that the observed initial increase in resistance can be attributed to electron–hole scattering, while the decrease follows naturally from the change in Fermi energy of the charge carriers. Both effects are governed dominantly by a van Hove singularity in the bulk valence band. The results demonstrate the importance of interband electron–hole scattering in the transport properties of topological insulators.

Thermoelectric Transport in a Three-Dimensional HgTe Topological Insulator

“…It is worth noting that we also compared the experiment with the monopolar model (Equation ( 8)), considering independent 2D electron and 3D hole contribution to thermopower only (not shown here). Indeed, we obtained considerable disagreement between the theory and the experiment, which supports the evidence of mutual electron-hole friction in our system [7,8,15].…”

“…Such mutual scattering has been detected directly in the resistance behavior [8,9]. Note that recently, 2D electron-3D hole scattering has been deduced from the nonmonotonic differential resistance of narrow 3DTI HgTe channels [15].…”