Tunable two-dimensional electron gas at the surface of thermoelectric material In$_4$Se$_3$

TL;DR

This paper reports the discovery of a thermally tunable two-dimensional electron gas at the surface of In$_4$Se$_3$, revealing its potential for controllable surface electronic properties in thermoelectric materials.

Contribution

It demonstrates the existence and thermal tunability of 2DEG on In$_4$Se$_3$ surface, a novel finding in thermoelectric materials.

Findings

2DEG exhibits nearly isotropic band dispersion

Carrier density shows significant temperature dependence

Unconventional metal-semiconductor transition observed

Abstract

We report the discovery of two-dimensional electron gas (2DEG) at the surface of thermoelectric material In$_4$Se$_3$ by angle-resolved photoemission spectroscopy. The observed 2DEG exhibits a nearly isotropic band dispersion with a considerably small effective mass of m* = 0.16 m_0, and its carrier density shows a significant temperature dependence, leading to unconventional metal-semiconductor transition at the surface. The observed wide-range thermal tunability of 2DEG in In$_4$Se$_3$ gives rise to additional degrees of freedom to better control the surface carriers of semiconductors.