Direct observation of electron emission from grain boundaries in CVD diamond by PeakForce-controlled tunnelling atomic force microscopy
| Autor: | Paul W May, Oliver J. L. Fox, Robert L. Harniman, Wiebke Janssen, Ken Haenen, Sien Drijkoningen |
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| Rok vydání: | 2015 |
| Předmět: |
Materials science
Chemistry(all) Condensed matter physics Tuna field emission Material properties of diamond Doping Diamond Nanotechnology General Chemistry Chemical vapor deposition engineering.material Grain size Field electron emission Surface conductivity engineering General Materials Science Grain boundary |
| Zdroj: | Harniman, R, Fox, O, Janssen, W, Drijkoningen, S, Haenen, K & May, P 2015, ' Direct observation of electron emission from grain boundaries in CVD diamond by PeakForce-controlled tunnelling atomic force microscopy ', Carbon, vol. 94, pp. 386-395 . https://doi.org/10.1016/j.carbon.2015.06.082 |
| ISSN: | 0008-6223 |
| DOI: | 10.1016/j.carbon.2015.06.082 |
| Popis: | A detailed investigation of electron emission from a set of chemical vapour deposited (CVD) diamond films is reported using high-resolution PeakForce-controlled tunnelling atomic force microscopy (PF-TUNA). Electron field emission originates preferentially from the grain boundaries in low-conductivity polycrystalline diamond samples, and not from the top of features or sharp edges. Samples with smaller grains and more grain boundaries, such as nanocrystalline diamond, produce a higher emission current over a more uniform area than diamond samples with larger grain size. Light doping with N, B or P increases the grain conductivity, with the result that the emitting grain-boundary sites become broader as the emission begins to creep up the grain sidewalls. For heavy B doping, where the grains are now more conducting than the grain boundaries, emission comes from both the grain boundaries and the grains almost equally. Lightly P-doped diamond samples show emission from step-edges on the (111) surfaces. Emission intensity was time dependent, with the measured current dropping to similar to 10% of its initial value similar to 30 h after removal from the CVD chamber. This decrease is ascribed to the build-up of adsorbates on the surface along with an increase in the surface conductivity due to surface transfer doping. (C) 2015 The Authors. Published by Elsevier Ltd. PWM thanks the EPSRC for financial support through grant EP/H043292/1. PF-TUNA was conducted in the Imaging Unit of the School of Chemistry, University of Bristol. KH thanks the Research Foundation - Flanders (FWO) for financial support through project G.0456.12. The raw data for the figures and analysis in this paper can be accessed via the University of Bristol data repository, doi: 10.5523/ bris.1pfcexif69sm81we336206dzdc. |
| Databáze: | OpenAIRE |
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