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Systematic Study of Oxygen Vacancy Tunable Transport Properties of Few‐Layer MoO 3− x Enabled by Vapor‐Based Synthesis
Author(s) -
Hanson Eve D.,
Lajaunie Luc,
Hao Shiqiang,
Myers Benjamin D.,
Shi Fengyuan,
Murthy Akshay A.,
Wolverton Chris,
Arenal Raul,
Dravid Vinayak P.
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201605380
Subject(s) - materials science , molybdenum trioxide , doping , density functional theory , x ray photoelectron spectroscopy , vacancy defect , electron energy loss spectroscopy , oxygen , chemical vapor deposition , nanotechnology , transmission electron microscopy , chemical engineering , molybdenum , optoelectronics , crystallography , computational chemistry , chemistry , organic chemistry , engineering , metallurgy
Bulk and nanoscale molybdenum trioxide (MoO 3 ) has shown impressive technologically relevant properties, but deeper investigation into 2D MoO 3 has been prevented by the lack of reliable vapor‐based synthesis and doping techniques. Herein, the successful synthesis of high‐quality, few‐layer MoO 3 down to bilayer thickness via physical vapor deposition is reported. The electronic structure of MoO 3 can be strongly modified by introducing oxygen substoichiometry (MoO 3− x ), which introduces gap states and increases conductivity. A dose‐controlled electron irradiation technique to introduce oxygen vacancies into the few‐layer MoO 3 structure is presented, thereby adding n‐type doping. By combining in situ transport with core‐loss and monochromated low‐loss scanning transmission electron microscopy–electron energy‐loss spectroscopy studies, a detailed structure–property relationship is developed between Mo‐oxidation state and resistance. Transport properties are reported for MoO 3− x down to three layers thick, the most 2D‐like MoO 3− x transport hitherto reported. Combining these results with density functional theory calculations, a radiolysis‐based mechanism for the irradiation‐induced oxygen vacancy introduction is developed, including insights into favorable configurations of oxygen defects. These systematic studies represent an important step forward in bringing few‐layer MoO 3 and MoO 3− x into the 2D family, as well as highlight the promise of MoO 3− x as a functional, tunable electronic material.