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Title: Structural and nanomechanical properties of nanocrystalline carbon thin films for photodetection

This paper reports the effect of helium gas pressure upon the structural, nanomechanical, and photoconductive properties of nanocrystalline carbon thin (NCT) films deposited by the filtered cathodic jet carbon arc technique. High-resolution transmission electron microscopy images confirm the nanocrystalline nature of the deposited films with different crystallite sizes (3–7 nm). The chemical structure of the deposited films is further analyzed by x-ray photoelectron spectroscopy and Raman spectroscopy, which suggest that the deposited films change from graphitelike to diamondlike, increasing in sp{sup 3} content, with a minor change in the dilution of the inert gas (helium). The graphitic character is regained upon higher dilution of the helium gas, whereupon the films exhibit an increase in sp{sup 2} content. The nanomechanical measurements show that the film deposited at a helium partial pressure of 2.2 × 10{sup −4} has the highest value of hardness (37.39 GPa) and elastic modulus (320.50 GPa). At a light intensity of 100 mW/cm{sup 2}, the NCT films deposited at 2.2 × 10{sup −4} and 0.1 mbar partial pressures of helium gas exhibit good photoresponses of 2.2% and 3.6%, respectively.
Authors:
 [1] ; ; ;  [2] ;  [3] ;  [4]
  1. Department of Physics, Kirorimal College, University of Delhi, Delhi 110007 (India)
  2. Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)
  3. Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)
  4. Ultrafast Optoelectronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)
Publication Date:
OSTI Identifier:
22392175
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 33; Journal Issue: 3; Other Information: (c) 2015 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTALS; DEPOSITS; GRAPHITE; HELIUM; NANOSTRUCTURES; NEUTRON CAPTURE THERAPY; PARTIAL PRESSURE; PRESSURE RANGE GIGA PA; RAMAN SPECTROSCOPY; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY PHOTOELECTRON SPECTROSCOPY