Electronic, Optical, and Thermoelectric Properties of Bulk and Monolayer Germanium Tellurides

Wenny V Sinambela,Sasfan A Wella,Fitri S Arsyad,Nguyen Tuan Hung,Ahmad R T Nugraha

doi:10.3390/cryst11111290

Wenny V Sinambela, Sasfan A Wella + Show 3 more

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https://doi.org/10.3390/cryst11111290

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Journal: Crystals	Publication Date: Oct 25, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Sriwijaya University, Tohoku University

Abstract

Electronic, optical, and thermoelectric properties of germanium tellurides (GeTe) were investigated through a series of first-principles calculations of band structures, absorption coefficients, and thermoelectric transport coefficients. We consider bulk GeTe to consist of cubic and rhombohedral phases, while the two-dimensional (2D) GeTe monolayers can form as a 2D puckered or buckled honeycomb crystals. All of the GeTe variants in the bulk and monolayer shapes are excellent light absorbers in a wide frequency range: (1) bulk cubic GeTe in the near-infrared regime, (2) bulk rhombohedral GeTe and puckered monolayer GeTe in the visible-light regime, and (3) buckled monolayer GeTe in the ultraviolet regime. We also found specifically that the buckled monolayer GeTe exhibits remarkable thermoelectric performance compared to the other GeTe phases due to a combination of electronic band convergence, a moderately wide band gap, and unique 2D density of states from the quantum confinement effect.

Highlights

Growing worldwide demand for energy and environmental impact associated with conventional energy sources is at the base of a probable energy crisis soon
By using first-principles density functional theory (DFT) approach, we focus on investigating the electronic, optical, and thermoelectric properties of germanium tellurides (GeTe) monolayers and compare the properties with those of bulk GeTe
Besides checking the consistency of the published literature, as a unique finding in this work, we show the potential of buckled GeTe monolayer as a thermoelectric material

Summary

Introduction

Growing worldwide demand for energy and environmental impact associated with conventional energy sources is at the base of a probable energy crisis soon. This situation is well known as the economy, energy, and environment (“3E”) trilemma [1]. Available solar energy in the environment and the waste heat given off by engines and machines are examples of energy sources that we can convert to electrical power For such energy conversions, we need materials that are excellent at absorbing light [2] and efficient in transforming heat directly to electricity [3]

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