Field emission properties of single crystalline W5O14 and W18O49 nanowires

0524948 - ÚPT 2021 RIV NL eng J - Journal Article
Saqib, M. - Jelenc, J. - Pirker, L. - Škapin, S.D. - De Pietro, L. - Ramsperger, U. - Knápek, Alexandr - Müllerová, Ilona - Remškar, M.
Field emission properties of single crystalline W5O14 and W18O49 nanowires.
Journal of Electron Spectroscopy and Related Phenomena. Roč. 241, MAY (2020), č. článku 146837. ISSN 0368-2048. E-ISSN 1873-2526
R&D Projects: GA TA ČR(CZ) TE01020118
EU Projects: European Commission(XE) 606988 - SIMDALEE2
Institutional support: RVO:68081731
Keywords : nanowires * tungsten oxides * electron emitter * field enhancement factor * work function
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 1.957, year: 2020
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S0368204818301567

Single crystalline tungsten oxides in a form of W 5 O 14 and W 18 O 49 nanowires were synthesized by iodine transport method. The morphology, work functions and field emission properties of these nanowires were investigated. Work functions of the W 5 O 14 (4.20–4.34 eV) and W 18 O 49 (4.55–4.57 eV) nanowires (NWs) have been measured by Kelvin probe force microscopy (KPFM) in ultra-high vacuum. Field emission (FE) measurements of individual nanowires were performed in ultra-high vacuum at microscopic and macroscopic distances between the emitter and electron collector. The obtained FE curves at microscopic distances were analyzed in the framework of the Fowler–Nordheim (F–N) theory. Field enhancement factors of W 5 O 14 at the emitter-collector distance of 2, 4 and 5 μm were calculated to be 110 ± 10, 180 ± 25 and 210 ± 30, respectively, and 125 ± 15 for W18O49 at 2 μm. At macroscopic distances, the F–N theory revealed unrealistic high field enhancement factors: for W 5 O 14 at 1 mm it was 17,000 ± 500, and for W 18 O 49 , the field enhancement factors were 5050 ± 30 and 6450 ± 30 at 600 μm and 800 μm emitter-collector distance, respectively. Therefore, more realistic model was discussed. The lower work function and typically smaller diameter of the W 5 O 14 nanowires in comparison with the W 18 O 49 wires, range the W 5 O 14 nanowires to the promising sources of electrons in field emission devices.
Permanent Link: http://hdl.handle.net/11104/0309164