Anisotropic Infrared Response and Orientation-dependent Strain-tuning of the Electronic Structure in Nb2SiTe4

TL;DR

This study demonstrates the strain-tunable anisotropic infrared response of Nb2SiTe4, revealing axis-dependent optical transitions and potential for polarization-sensitive optoelectronic applications.

Contribution

It introduces Nb2SiTe4 as a new 2D material with unique strain-dependent anisotropic optical properties, supported by experimental and theoretical analysis.

Findings

Optical transitions are axis-dependent and can shift oppositely under strain.

G0W0-BSE calculations agree with experimental extinction spectra.

Strain effects explained by orbital coupling analysis.

Abstract

Two-dimensional materials with tunable in-plane anisotropic infrared response promise versatile applications in polarized photodetectors and field-effect transistors. Black phosphorus is a prominent example. However, it suffers from poor ambient stability. Here, we report the strain-tunable anisotropic infrared response of a layered material Nb2SiTe4, whose lattice structure is similar to the 2H-phase transition metal dichalcogenides (TMDCs) with three different kinds of building units. Strikingly, some of the strain-tunable optical transitions are crystallographic axis-dependent, even showing opposite shift when uniaxial strain is applied along two in-plane principal axes. Moreover, G0W0-BSE calculations show good agreement with the anisotropic extinction spectra. The optical selection rules are obtained via group theory analysis, and the strain induced unusual shift trends are well explained by the orbital coupling analysis. Our comprehensive study suggests that Nb2SiTe4 is a good candidate for tunable polarization-sensitive optoelectronic devices.