Determining Bandgaps in the Layered Group-10 2D Transition Metal Dichalcogenide PtSe2

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27360%2F24%3A10255792" target="_blank" >RIV/61989100:27360/24:10255792 - isvavai.cz</a>

Výsledek na webu

<a href="https://onlinelibrary.wiley.com/doi/10.1002/adfm.202408982" target="_blank" >https://onlinelibrary.wiley.com/doi/10.1002/adfm.202408982</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1002/adfm.202408982" target="_blank" >10.1002/adfm.202408982</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Determining Bandgaps in the Layered Group-10 2D Transition Metal Dichalcogenide PtSe2

Popis výsledku v původním jazyce

Unlike traditional group-6 transition metal dichalcogenides (TMDs), group-10 TMDs such as PtSe2 and PdTe2 possess highly tuneable indirect bandgaps, transitioning from semiconducting in the near-infrared to semimetal behavior with a number of monolayers (MLs). This opens up the possibility of TMD-based mid-infrared and terahertz optoelectronics. Despite this large potential, the optical properties of such materials have shown an extremely large disparity between that predicted and measured. For example, simulations show that a few MLs is required for the semiconductor-semimetal transition, whilst tens of MLs is found experimentally. This is a result of widely used optical extrapolation methods to determine bandgaps, such as the Tauc plot approach, that are not adapted here owing to i) nearby direct transitions, ii) the material dimensionality and iii) large changes in the non-parabolic bandstructure with MLs. Here, uniquely combining optical ellipsometry to determine the complex permittivity, terahertz time resolved spectroscopy for the complex conductivity and in-depth density functional theory (DFT) simulations, it is shown that the optical properties and bandstructure can be determined reliably and demonstrate clearly that the semiconductor-semimetal transition occurs for PtSe2 layers ALMOST EQUAL TO5 MLs. The microscopic origins of the observed transitions and the crucial role of the Coulomb interaction for thin semiconducting layers, and that of interlayer van der Waals forces for multilayer semimetallic samples are also demonstrated. This work of combining complimentary experimental techniques and extensive simulations avoids the application of constrained extrapolation methods to determine the optical properties of group-10 TMDs, and will be of importance for future mid-infrared and terahertz applications.

Název v anglickém jazyce

Determining Bandgaps in the Layered Group-10 2D Transition Metal Dichalcogenide PtSe2

Popis výsledku anglicky

Unlike traditional group-6 transition metal dichalcogenides (TMDs), group-10 TMDs such as PtSe2 and PdTe2 possess highly tuneable indirect bandgaps, transitioning from semiconducting in the near-infrared to semimetal behavior with a number of monolayers (MLs). This opens up the possibility of TMD-based mid-infrared and terahertz optoelectronics. Despite this large potential, the optical properties of such materials have shown an extremely large disparity between that predicted and measured. For example, simulations show that a few MLs is required for the semiconductor-semimetal transition, whilst tens of MLs is found experimentally. This is a result of widely used optical extrapolation methods to determine bandgaps, such as the Tauc plot approach, that are not adapted here owing to i) nearby direct transitions, ii) the material dimensionality and iii) large changes in the non-parabolic bandstructure with MLs. Here, uniquely combining optical ellipsometry to determine the complex permittivity, terahertz time resolved spectroscopy for the complex conductivity and in-depth density functional theory (DFT) simulations, it is shown that the optical properties and bandstructure can be determined reliably and demonstrate clearly that the semiconductor-semimetal transition occurs for PtSe2 layers ALMOST EQUAL TO5 MLs. The microscopic origins of the observed transitions and the crucial role of the Coulomb interaction for thin semiconducting layers, and that of interlayer van der Waals forces for multilayer semimetallic samples are also demonstrated. This work of combining complimentary experimental techniques and extensive simulations avoids the application of constrained extrapolation methods to determine the optical properties of group-10 TMDs, and will be of importance for future mid-infrared and terahertz applications.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10306 - Optics (including laser optics and quantum optics)

Projekt

<a href="/cs/project/EH22_008%2F0004631" target="_blank" >EH22_008/0004631: Materiály a technologie pro udržitelný rozvoj</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2024

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Advanced Functional Materials

ISSN

1616-301X

e-ISSN

1616-3028

Svazek periodika

Neuveden

Číslo periodika v rámci svazku

17 October 2024

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

11

Strana od-do

2408982

Kód UT WoS článku

001338476400001

EID výsledku v databázi Scopus

2-s2.0-85206468571