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Description:

To expand the applications of low work function materials, high chemical stability is necessary to prevent the surface from unfavorable reactions. We developed a 20-nm-thick LaB6 thin film covered by a monolayer h-BN, which exhibits not only low work function but also high chemical stability. Results demonstrated that the h-BN/LaB6 heterostructure can be formed by vacuum annealing a nitrogen-doped LaB6 thin film. The formation process was investigated using AES, HREELS, and XANES spectroscopy. We have elucidated that the doped nitrogen atoms and boron atoms in the film thermally diffuse into the surface during annealing, thereby forming the monolayer h-BN on the surface. Work function was measured using STM. From a practical perspective, chemical stability was evaluated with a heating temperature necessary for restoring the low work function state after air exposure. The work function was comparable to that of the clean LaB6(100) surface. Moreover, it recovered at a much lower temperature than the cleaning temperature of the LaB6(100) surface. We anticipate that this material development will facilitate implementation of the low work function material.

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• Creative Commons BY-NC Attribution-NonCommercial 4.0 International
  

Keyword: heterostructure thin film, lanthanum hexaboride (LaB6), low work function, monolayer hexagonal boron nitride (h-BN)

Date published: 2024-06-06

Publisher: Elsevier BV

Journal:

• Applied Surface Science (ISSN: 01694332) vol. 669 160478

Funding:

• JSPS 17K05066,
• JSPS 19H00758
• JSPS 15K13969

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.apsusc.2024.160478

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Updated at: 2024-06-19 16:30:16 +0900

Published on MDR: 2024-06-19 16:30:16 +0900