Self-Limiting Layer-by-Layer Oxidation of Atomically Thin WSe2

• Published in: Nano letters Vol. 15; no. 3; pp. 2067 - 2073
• Main Authors: Yamamoto, Mahito, Dutta, Sudipta, Aikawa, Shinya, Nakaharai, Shu, Wakabayashi, Katsunori, Fuhrer, Michael S, Ueno, Keiji, Tsukagoshi, Kazuhito
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.03.2015
• Subjects: photoluminescence; ab initio calculations; oxidation; Layered transition metal dichalcogenides; Raman spectroscopy; X-ray photoelectron spectroscopy; tungsten diselenide
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl5049753

Growth of a uniform oxide film with a tunable thickness on two-dimensional transition metal dichalcogenides is of great importance for electronic and optoelectronic applications. Here we demonstrate homogeneous surface oxidation of atomically thin WSe2 with a self-limiting thickness from single- to trilayers. Exposure to ozone (O3) below 100 °C leads to the lateral growth of tungsten oxide selectively along selenium zigzag-edge orientations on WSe2. With further O3 exposure, the oxide regions coalesce and oxidation terminates leaving a uniform thickness oxide film on top of unoxidized WSe2. At higher temperatures, oxidation evolves in the layer-by-layer regime up to trilayers. The oxide films formed on WSe2 are nearly atomically flat. Using photoluminescence and Raman spectroscopy, we find that the underlying single-layer WSe2 is decoupled from the top oxide but hole-doped. Our findings offer a new strategy for creating atomically thin heterostructures of semiconductors and insulating oxides with potential for applications in electronic devices.