The Schottky-Mott Rule Expanded for Two-Dimensional Semiconductors: Influence of Substrate Dielectric Screening
| Autor: | Dongguen Shin, Areej Aljarb, Patrick Amsalem, S. Blumstengel, Lain-Jong Li, Soohyung Park, Xiaomin Xu, Thorsten Schultz, Niklas Mutz, Hee Seong Kang, Emil J. W. List-Kratochvil, Norbert Koch, Chul Ho Lee, Vincent Tung |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
ionization energy Band gap photoelectron spectroscopy General Physics and Astronomy Dielectric Electron MoS2 monolayer 2D semiconductors electron affinity Fermi level pinning Condensed Matter::Materials Science Monolayer General Materials Science Work function Condensed matter physics business.industry General Engineering Schottky diode 540 Chemie und zugeordnete Wissenschaften Semiconductor ddc:540 Vacuum level business |
| Zdroj: | ACS nano. 15(9) |
| ISSN: | 1936-086X |
| Popis: | A comprehensive understanding of the energy level alignment mechanisms between two dimensional 2D semiconductors and electrodes is currently lacking, but it is a prerequisite for tailoring the interface electronic properties to the requirements of device applications. Here, we use angle resolved direct and inverse photoelectron spectroscopy to unravel the key factors that determine the level alignment at interfaces between a monolayer of the prototypical 2D semiconductor MoS2 and conductor, semiconductor, and insulator substrates. For substrate work function amp; 934;sub values below 4.5 eV we find that Fermi level pinning occurs, involving electron transfer to native MoS2 gap states below the conduction band. For amp; 934;sub above 4.5 eV, vacuum level alignment prevails but the charge injection barriers do not strictly follow the changes of amp; 934;sub as expected from the Schottky Mott rule. Notably, even the trends of the injection barriers for holes and electrons are different. This is caused by the band gap renormalization of monolayer MoS2 by dielectric screening, which depends on the dielectric constant amp; 949;r of the substrate. Based on these observations, we introduce an expanded Schottky Mott rule that accounts for band gap renormalization by amp; 949;r dependent screening and show that it can accurately predict charge injection barriers for monolayer MoS2. It is proposed that the formalism of the expanded Schottky Mott rule should be universally applicable for 2D semiconductors, provided that material specific experimental benchmark data are available |
| Databáze: | OpenAIRE |
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