Oxidative and Adsorbent Impacts on Selenide Based Transition Metal Dichalcogenides

This paper covers an overview of the transition metal dichalcogenides, TMD, class of materials. Their layered van der Waals chemical structure and unique electrical and optical properties, such as an indirect in the bulk to direct band gap in the monolayer transition, has brought research focus to their potential role in nanoelectronics. This paper goes over general TMD properties then focuses on WSe₂. While TMDs posses useful and promising characteristics in their pristine state, without precise control over electrical behavior real world application will never occur. Defect engineering is discussed as a method to tune TMD properties, specifically the effects of O₂ plasma exposure which oxidized the top most layer of TMD selenides and p-dopes the underlying pristine material.

A version of Chapter 1 was originally published by Anna N. Hoffman, Michael G. Stanford, Cheng Zhang, Ilia N. Ivanov, Akinola D. Oyedele, Maria Gabriela Sales, Stephen J. McDonnell, Michael R. Koehler, David G. Mandrus, Liangbo Liang, Bobby G. Sumpter, Kai Xiao, and Philip D. Rack: Hoffman, A. N.; Stanford, M. G.; Zhang, C.; Ivanov, I. N.; Oyedele, A. D.; Sales, M. G.; McDonnell, S. J.; Koehler, M. R.; Mandrus, D. G.; Liang, L.; et al. Atmospheric and Long-Term Aging Effects on the Electrical Properties of Variable Thickness WSe2 Transistors. ACS Appl. Mater. Interfaces 2018, 36540-36548 Anna N. Hoffman conducted the device fabrication, electrical, and optical characterization, analysis and wrote the manuscript. Michael G. Stanford, Cheng Zhang, Ilia N. Ivanov, Akinola D. Oyedele, and Kai Xiao facilitated device fabrication training and helped with the electrical and Raman measurements; Maria Gabriela Sales and Stephen J. McDonnell performed XPS characterization. Liangbo Liang and Bobby G. Sumpter performed DTF calculations. Michael R. Koehler and David G. Mandrus grew the WSe2 bulk crystals. The manuscript was written through contributions of all authors. The manuscript has been slightly modified to include the supplemental material.