Electron dephasing in homogeneous and inhomogeneous indium tin oxide thin films

TL;DR

This study investigates electron dephasing in indium tin oxide thin films across a broad temperature range, revealing dominant electron-electron scattering processes and a weak temperature dependence of dephasing time at very low temperatures.

Contribution

It provides new insights into dephasing mechanisms in ITO films, highlighting the role of electron-electron interactions and the weak electron-phonon relaxation in low-carrier-concentration materials.

Findings

Electron-electron scattering dominates dephasing from a few K to tens K.

A crossover to large-energy-transfer e-e scattering occurs at higher temperatures.

Dephasing time scales inversely with electron diffusion constant at very low temperatures.

Abstract

The electron dephasing processes in two-dimensional homogeneous and inhomogeneous indium tin oxide thin films have been investigated in a wide temperature range 0.3--90 K. We found that the small-energy-transfer electron-electron ($e$-$e$) scattering process dominated the dephasing from a few K to several tens K. At higher temperatures, a crossover to the large-energy-transfer $e$-$e$ scattering process was observed. Below about 1--2 K, the dephasing time $\tau_\varphi$ revealed a very weak temperature dependence, which intriguingly scaled approximately with the inverse of the electron diffusion constant $D$, i.e., $\tau_\varphi (T \approx 0.3 \, {\rm K}) \propto 1/D$. Theoretical implications of our results are discussed. The reason why the electron-phonon relaxation rate is negligibly weak in this low-carrier-concentration material is presented.