Titanium trisulfide (TiS3): a 2D semiconductor with quasi-1D optical and electronic properties

TL;DR

This paper characterizes few-layer TiS3, revealing its strong in-plane anisotropy in electrical and optical properties, and introduces a method to identify its crystalline axes, highlighting its potential for anisotropic optoelectronic applications.

Contribution

It provides detailed experimental analysis of TiS3's anisotropic properties and develops a polarization Raman spectroscopy method to determine its crystalline axes.

Findings

High in-plane mobility anisotropy ratio of 7.6 at low temperatures

Strong linear dichroism with transmission ratios up to 30

Good agreement between calculated and experimental optical spectra

Abstract

We present characterizations of few-layer titanium trisulfide (TiS3) flakes which, due to their reduced in-plane structural symmetry, display strong anisotropy in their electrical and optical properties. Exfoliated few-layer flakes show marked anisotropy of their in-plane mobilities reaching ratios as high as 7.6 at low temperatures. Based on the preferential growth axis of TiS3 nanoribbons, we develop a simple method to identify the in-plane crystalline axes of exfoliated few-layer flakes through angle resolved polarization Raman spectroscopy. Optical transmission measurements show that TiS3 flakes display strong linear dichroism with a magnitude (transmission ratios up to 30) much greater than that observed for other anisotropic two-dimensional (2D) materials. Finally, we calculate the absorption and transmittance spectra of TiS3 in the random-phase-approximation (RPA) and find that the calculations are in good agreement with the observed experimental optical transmittance.