Widely Tunable Optical and Thermal Properties of Dirac Semimetal Cd$_3$As$_2$

TL;DR

This study investigates the temperature-dependent optical properties of Cd$_3$As$_2$, revealing large thermo-optic shifts and tunable optical responses driven by Fermi level adjustments, with implications for nanophotonic and nanoelectronic applications.

Contribution

It provides a comprehensive analysis combining experimental measurements and first-principles calculations of the optical and thermal properties of Cd$_3$As$_2$, a 3D Dirac semimetal, highlighting its tunability.

Findings

Large thermo-optic shifts surpassing traditional semiconductors.

Fermi level tuning significantly affects optical responses.

Quantified electron scattering and effective mass variations.

Abstract

In this paper we report a detailed analysis of the temperature-dependent optical properties of epitaxially grown cadmium arsenide (Cd$_3$As$_2$), a newly discovered three-dimensional Dirac semimetal. Dynamic Fermi level tuning -- instigated from Pauli-blocking in the linear Dirac cone -- and varying Drude response, generate large variations in the mid and far-infrared optical properties. We demonstrate thermo-optic shifts larger than those of traditional III-V semiconductors, which we attribute to the obtained large thermal expansion coefficient as revealed by first-principles calculations. Electron scattering rate, plasma frequency edge, Fermi level shift, optical conductivity, and electron effective mass analysis of Cd$_3$As$_2$ thin-films are quantified and discussed in detail. Our ab initio density functional study and experimental analysis of epitaxially grown Cd$_3$As$_2$ promise applications for nanophotonic and nanoelectronic devices, such as reconfigurable metamaterials and metasurfaces, nanoscale thermal emitters, and on-chip directional antennas.