Optical and Structural Properties of Multi-wall-carbon-nanotube-modified ZnO Synthesized  at Varying Substrate Temperatures for Highly Efficient Light Sensing Devices

Valentine Saasa; Malose Mokwena; Baban Dhonge; Elayaperumal Manikandan; John Kennedy; Peter P. Murmu; John Dewar; Rudolph Erasmus; Maria Fernandez Whaley; Emmanuel Mukwevho; Bonex Mwakikunga

Sensors & Transducers (Dec 2015)

Optical and Structural Properties of Multi-wall-carbon-nanotube-modified ZnO Synthesized at Varying Substrate Temperatures for Highly Efficient Light Sensing Devices

Valentine Saasa,
Malose Mokwena,
Baban Dhonge,
Elayaperumal Manikandan,
John Kennedy,
Peter P. Murmu,
John Dewar,
Rudolph Erasmus,
Maria Fernandez Whaley,
Emmanuel Mukwevho,
Bonex Mwakikunga

Affiliations

Valentine Saasa: DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001, South Africa,
Malose Mokwena: DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001, South Africa,
Baban Dhonge: DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001, South Africa,
Elayaperumal Manikandan: Department of Biochemistry, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
John Kennedy: National Isotope Centre, GNS Science, 30 Gracefield Road, PO Box 31312, Lower Hutt 5010, New Zealand
Peter P. Murmu: National Isotope Centre, GNS Science, 30 Gracefield Road, PO Box 31312, Lower Hutt 5010, New Zealand
John Dewar: Department of Life and Consumer Sciences, University of South Africa (UNISA), Florida Campus, Johannesburg, South Africa
Rudolph Erasmus: Centre of Excellence in Strong Materials, Department of Physics, University of the Witwatersrand, Private Bag 3, PO Box 2050, Johannesburg, South Africa
Maria Fernandez Whaley: Organic Analysis Laboratory, National Metrology Institute of South Africa, Pretoria, South Africa
Emmanuel Mukwevho: Department of Biochemistry, North West University, Private Bag X2046, Mmabatho 2735, South Africa
Bonex Mwakikunga: DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001, South Africa,

Journal volume & issue: Vol. 195, no. 12
pp. 9 – 17

Abstract

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Structural, optical and light detection properties on carbon-nanotube-modified ZnO thin films grown at various temperatures from room to 1173 K are investigated. The optical band gap values calculated from reflectivity data show a hump at a critical temperature range of 873-1073 K. Similar trends in surface roughness as well as crystallite size of the films are observed. These changes have been attributed to structural change from wurzite hexagonal to cubic carbon modified ZnO as also validated by x-ray diffraction, RBS and PIXE of these layers. UV and visible light detection properties show similar trends. It is demonstrated that the present films can sense both UV and visible light to a maximum response efficiency of 66 % which is much higher than the last reported efficiency 10 %. This high response is given predominantly by cubic crystallite rather than the wurzite hexagonal composites.

Published in Sensors & Transducers

ISSN: 2306-8515 (Print); 1726-5479 (Online)
Publisher: IFSA Publishing, S.L.
Country of publisher: Spain
LCC subjects: Technology: Technology (General)
Website: http://www.sensorsportal.com/HTML/DIGEST/New_Digest.htm

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