Exciton states and oscillator strength in few-layer α-tellurene

Abstract

Tellurene is an elementary two-dimensional (2D) semiconductor material that has attracted intensive attention. Here, first-principles methods are used to explore the effects of excitons on the optical properties of few-layer α-tellurene by considering the thickness and strain effects. Compared to other 2D materials, an α-tellurene monolayer possesses the characteristics of bound exciton states with a binding energy of 0.18 eV and a high optical absorption and oscillator strength in the infrared region. In addition, increasing the thickness and biaxial strain can cause a red-shift of the absorption spectra. The obtained results enrich the current understanding of the underlying physical mechanisms of α-tellurene, which are useful when designing related optoelectronic nanodevices.