Linear dichroism of the optical properties of SnS and SnSe van der Waals crystals

TL;DR

This study investigates the linear dichroism in SnS and SnSe van der Waals crystals, revealing their polarization-sensitive optical properties and electronic structure, which are promising for near-infrared photodetectors and device applications.

Contribution

It provides a comprehensive analysis combining optical spectroscopy, photoemission spectroscopy, and ab initio calculations to understand the anisotropic optical and electronic properties of SnS and SnSe.

Findings

High sensitivity of optical response to light polarization

Determined ionization potential, electron affinity, and work function

Insights into electronic band dispersion and orbital composition

Abstract

Tin monochalcogendies SnS and SnSe, belonging to a familiy of van der Waals crystals isoelectronic to black phosphorus, are know as enivornmetally-friendly materials promisng for thermoelecric conversion applications. However, they exhibit other desired functionalities, such as intrisic linear dichroism of the optical and electronic properties originating from strongly anisotropic orthorhombic crystal structure. This property makes them perfect candidats for polarization-sensitive photodetectors working in near infrared spectral range. We present a comprehensive study of the SnS and SnSe crystals by means of optical spectroscopy and photoemission spectroscopy, supported by ab initio calcualtions. The studies revealed the high sensitivity of the optical response of both materials to the incident light polarization, which we interpret in terms of the electronic band dispersion and orbital composition of the electronic bands, dictating the selection rules. From the photoemission investigation we determine the ionization potential, electron affinity and work function, which are parameters crucial for the design of devices based on semiconductor heterostructures.