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Optical manipulation of work function contrasts on metal thin films

Work function is a crucial metric in every optoelectronic device to ensure a specific charge transport scheme. However, the number of stable conductive materials available in a given work function range is scant, necessitating work function modulation. As opposed to all the previous chemical methods...

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Autores principales: Ravi, Sai Kishore, Sun, Wanxin, Nandakumar, Dilip Krishna, Zhang, Yaoxin, Tan, Swee Ching
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Association for the Advancement of Science 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837426/
https://www.ncbi.nlm.nih.gov/pubmed/29511737
http://dx.doi.org/10.1126/sciadv.aao6050
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author Ravi, Sai Kishore
Sun, Wanxin
Nandakumar, Dilip Krishna
Zhang, Yaoxin
Tan, Swee Ching
author_facet Ravi, Sai Kishore
Sun, Wanxin
Nandakumar, Dilip Krishna
Zhang, Yaoxin
Tan, Swee Ching
author_sort Ravi, Sai Kishore
collection PubMed
description Work function is a crucial metric in every optoelectronic device to ensure a specific charge transport scheme. However, the number of stable conductive materials available in a given work function range is scant, necessitating work function modulation. As opposed to all the previous chemical methods of work function modulation, we introduce here an alternative approach involving optical modulation. The work function is the minimum energy needed to eject an electron from a solid into vacuum and is known to be light-intensity–independent. A “light intensity dependent” change in work function was observed in metallic thin films coated on a semiconductor. This new phenomenon, contrasting the existing notions on work function, was tested and affirmed with three different systems, namely, Au/n-Si, Pt/n-Si, and W/n-Si. A work function shift of 0.22 eV is achieved in the Pt/n-Si system merely by tuning the illumination intensity from 0 to 18 mW/cm(2). Continuous tuning of work functions to a specified range is now possible just by tuning the light intensity with a few discrete metals in hand. Moreover, selective illumination creates a work function contrast on the metal film, enabling in-plane charge transport. This throws new light on the design and understanding of the optoelectronic devices. In light of this, we also present a simple photodetector design that is sensitive to illumination direction.
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spelling pubmed-58374262018-03-06 Optical manipulation of work function contrasts on metal thin films Ravi, Sai Kishore Sun, Wanxin Nandakumar, Dilip Krishna Zhang, Yaoxin Tan, Swee Ching Sci Adv Research Articles Work function is a crucial metric in every optoelectronic device to ensure a specific charge transport scheme. However, the number of stable conductive materials available in a given work function range is scant, necessitating work function modulation. As opposed to all the previous chemical methods of work function modulation, we introduce here an alternative approach involving optical modulation. The work function is the minimum energy needed to eject an electron from a solid into vacuum and is known to be light-intensity–independent. A “light intensity dependent” change in work function was observed in metallic thin films coated on a semiconductor. This new phenomenon, contrasting the existing notions on work function, was tested and affirmed with three different systems, namely, Au/n-Si, Pt/n-Si, and W/n-Si. A work function shift of 0.22 eV is achieved in the Pt/n-Si system merely by tuning the illumination intensity from 0 to 18 mW/cm(2). Continuous tuning of work functions to a specified range is now possible just by tuning the light intensity with a few discrete metals in hand. Moreover, selective illumination creates a work function contrast on the metal film, enabling in-plane charge transport. This throws new light on the design and understanding of the optoelectronic devices. In light of this, we also present a simple photodetector design that is sensitive to illumination direction. American Association for the Advancement of Science 2018-03-02 /pmc/articles/PMC5837426/ /pubmed/29511737 http://dx.doi.org/10.1126/sciadv.aao6050 Text en Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). http://creativecommons.org/licenses/by-nc/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license (http://creativecommons.org/licenses/by-nc/4.0/) , which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.
spellingShingle Research Articles
Ravi, Sai Kishore
Sun, Wanxin
Nandakumar, Dilip Krishna
Zhang, Yaoxin
Tan, Swee Ching
Optical manipulation of work function contrasts on metal thin films
title Optical manipulation of work function contrasts on metal thin films
title_full Optical manipulation of work function contrasts on metal thin films
title_fullStr Optical manipulation of work function contrasts on metal thin films
title_full_unstemmed Optical manipulation of work function contrasts on metal thin films
title_short Optical manipulation of work function contrasts on metal thin films
title_sort optical manipulation of work function contrasts on metal thin films
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837426/
https://www.ncbi.nlm.nih.gov/pubmed/29511737
http://dx.doi.org/10.1126/sciadv.aao6050
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