Wang, M;
Ayesha Sharif, A;
Farid, N;
Vijayaraghavan, RK;
Choy, K-L;
McNally, PJ;
O'Connor, GM;
(2021)
Non-melt selective enhancement of crystalline structure in molybdenum thin films using femtosecond laser pulses.
Journal of Physics D: Applied Physics
, 55
(11)
, Article 115301. 10.1088/1361-6463/ac3e91.
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Abstract
It is challenging to crystalize a thin film of higher melting temperature when deposited on a substrate with comparatively lower melting point. Trading such disparities in thermal properties between a thin film and its substrate can significantly impede material processing. We report a novel solid-state crystallization process for annealing of high melting point molybdenum thin films. A systematic investigation of laser induced annealing from single pulse to high pulse overlapping is reported upon scanning at fluences lower than the threshold required for the damage/ablation of molybdenum thin films. The approach allows better control of the grain size by changing the applied laser fluence. Atomic force microscopy surface morphology and x-ray diffraction (XRD) analysis reveal significant improvements in the average polycrystalline grain size after laser annealing; the sheet resistance was reduced by 19% of the initial value measured by a Four-point probe system. XRD confirms the enlargement of the single crystal grain size. No melting was evident, although a change in the close packing, shape and size of nanoscale polycrystalline grains is observed. Ultrashort laser induced crystallinity greatly enhances the electrical properties; Hall measurements reinforced that the overall carrier concentration increases after scanning at different laser fluences. The proposed method, based on the aggregation and subsequent growth of polycrystalline and single crystal-grains, leading to enhanced crystallization, has potential to be applicable in thin film processing industry for their wide applications.
| Type: | Article |
|---|---|
| Title: | Non-melt selective enhancement of crystalline structure in molybdenum thin films using femtosecond laser pulses |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/1361-6463/ac3e91 |
| Publisher version: | https://doi.org/10.1088/1361-6463/ac3e91 |
| Language: | English |
| Additional information: | © 2021 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office > Institute for Materials Discovery |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10140397 |
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