Photon-Induced Selenium Vacancies in TiSe2

TL;DR

This study uses Raman spectroscopy to investigate how laser irradiation induces selenium vacancies in TiSe2, revealing a linear relationship between laser intensity and vacancy formation, which impacts its electronic properties.

Contribution

It provides the first detailed analysis of photon-induced selenium vacancies in TiSe2 and quantifies the activation energy for vacancy nucleation.

Findings

Laser irradiation creates selenium vacancies in TiSe2.

Two additional Raman peaks indicate selenium deficiency.

Linear dependence of vacancy formation on laser intensity.

Abstract

TiSe2 is a member of transition metal dichalcogenide family of layered van-der-Waals materials that exhibits some distinctive electronic and optical properties. Here, we perform Raman spectroscopy studies on single crystal TiSe2 to investigate photon-induced defects associated with formation of selenium vacancies. Two additional Eg phonon peaks are observed in the laser-irradiated regions, consistent with Raman spectra of selenium deficient TiSe2. Temperature dependent studies of the threshold laser intensity necessary to form selenium vacancies show that there is a linear dependence. We extract the relevant activation energy for selenium vacancy nucleation. The impact of these results on the properties of strongly correlated electron states in TiSe2 are discussed.