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Effect of SP 3/(SP 2+SP 3) Carbon Fraction on the Photoelectric Threshold and Electron Affinity of Diamond Films

Published online by Cambridge University Press:  10 February 2011

I.A. Akwani ,
E.D. Sosa ,
S.C. Lim ,
R.E. Stallcup II ,
J.N. Castillega ,
J. Bernhard ,
D.E. Golden  and
J.M. Perez
I.A. Akwani
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
E.D. Sosa
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
S.C. Lim
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
R.E. Stallcup II
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
J.N. Castillega
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
J. Bernhard
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
D.E. Golden
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
J.M. Perez
Affiliation:
Physics Department, University of North Texas, Denton, TX 76203
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Abstract

We report a significant decrease in the photoelectric threshold of chemical vapor deposition grown diamond films as the fraction of sp 3 carbon to sp 2 plus sp 3 carbon in the films decreases. Raman spectroscopy and x-ray photoelectron spectroscopy are used to characterize the different forms of carbon in the films and the sp 3/(sp 2 + sp 3) carbon fraction at the surface. We observe a decrease in the photoelectric threshold from 4.5 eV to 3.9 eV as the sp 3/(sp 2 + sp 3) carbon fraction at the surface decreases from 71% to 55%. Ultraviolet photoelectron spectroscopy of the films shows that they have a negative electron affinity surface. Therefore, the work function of the films decreases from 4.5 eV to 3.9 eV. We propose that the decrease in photoelectric threshold is due to a decrease in the band gap of sp 2-sp 3 carbon networks at the grain boundaries. The observed decrease in photoelectric threshold can be used to tailor the electronic properties of diamond films for specific applications.

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Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 509: Symposium C – Materials Issues in Vacuum Microelectronics , 1998 , 137
Copyright
Copyright © Materials Research Society 1998

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