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Title: Unintentional Doping and Compensation Effects of Carbon in Metal-Organic Chemical-Vapor Deposition Fabricated ZnO Thin Films

Abstract

Carbon is a typical impurity in thin films fabricated by metal-organic chemical-vapor deposition (MOCVD). The role of carbon in undoped and nitrogen-doped ZnO thin films was studied experimentally and theoretically to understand the possible compensation effects. ZnO thin films are fabricated by low-pressure MOCVD using diethylzinc, nitric oxide (for nitrogen-doped films), or oxygen precursors (for undoped films). Compared with sputtering-fabricated ZnO film, the carbon concentration in the MOCVD-fabricated ZnO film is very high. Furthermore, the MOCVD-fabricated ZnO:N film has an even higher carbon concentration than the undoped ZnO. Considering the signal observed previously by Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, it is possible that the incorporated carbon has formed complexes with doped nitrogen. The first-principles calculations predict that the formation energy for carbon interstitial (C{sub i}) is relatively high. However, due to the large binding energy between C{sub i} and N{sub O} (nitrogen substitute on oxygen site), the formation energy of the carbon-nitrogen (CN) defect complex is lower than that of the C{sub i}. As a result, with nitrogen doping, the carbon-impurity concentration would be high. In the insulator or p-type ZnO films, the CN defect complexes have 1+ charge state. Therefore, the existence of carbon in themore » ZnO:N film could be another possible passivation factor to the nitrogen acceptor, in addition to hydrogen.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
978487
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science Technology. A, Vacuum, Surfaces, and Films; Journal Volume: 24; Journal Issue: 5, September 2006
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BINDING ENERGY; CARBON; CHARGE STATES; DEFECTS; DEPOSITION; HYDROGEN; INTERSTITIALS; NITRIC OXIDE; NITROGEN; OXYGEN; PASSIVATION; SPECTROSCOPY; THIN FILMS; X-RAY PHOTOELECTRON SPECTROSCOPY; Solar Energy - Photovoltaics; Materials Science and Semiconductors

Citation Formats

Li, X., Asher, S. E., Limpijumnong, S., Zhang, S. B., Wei, S.-H., Barnes, T. M., Coutts, T. J., and Noufi, R. Unintentional Doping and Compensation Effects of Carbon in Metal-Organic Chemical-Vapor Deposition Fabricated ZnO Thin Films. United States: N. p., 2006. Web. doi:10.1116/1.2167981.
Li, X., Asher, S. E., Limpijumnong, S., Zhang, S. B., Wei, S.-H., Barnes, T. M., Coutts, T. J., & Noufi, R. Unintentional Doping and Compensation Effects of Carbon in Metal-Organic Chemical-Vapor Deposition Fabricated ZnO Thin Films. United States. doi:10.1116/1.2167981.
Li, X., Asher, S. E., Limpijumnong, S., Zhang, S. B., Wei, S.-H., Barnes, T. M., Coutts, T. J., and Noufi, R. Sun . "Unintentional Doping and Compensation Effects of Carbon in Metal-Organic Chemical-Vapor Deposition Fabricated ZnO Thin Films". United States. doi:10.1116/1.2167981.
@article{osti_978487,
title = {Unintentional Doping and Compensation Effects of Carbon in Metal-Organic Chemical-Vapor Deposition Fabricated ZnO Thin Films},
author = {Li, X. and Asher, S. E. and Limpijumnong, S. and Zhang, S. B. and Wei, S.-H. and Barnes, T. M. and Coutts, T. J. and Noufi, R.},
abstractNote = {Carbon is a typical impurity in thin films fabricated by metal-organic chemical-vapor deposition (MOCVD). The role of carbon in undoped and nitrogen-doped ZnO thin films was studied experimentally and theoretically to understand the possible compensation effects. ZnO thin films are fabricated by low-pressure MOCVD using diethylzinc, nitric oxide (for nitrogen-doped films), or oxygen precursors (for undoped films). Compared with sputtering-fabricated ZnO film, the carbon concentration in the MOCVD-fabricated ZnO film is very high. Furthermore, the MOCVD-fabricated ZnO:N film has an even higher carbon concentration than the undoped ZnO. Considering the signal observed previously by Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, it is possible that the incorporated carbon has formed complexes with doped nitrogen. The first-principles calculations predict that the formation energy for carbon interstitial (C{sub i}) is relatively high. However, due to the large binding energy between C{sub i} and N{sub O} (nitrogen substitute on oxygen site), the formation energy of the carbon-nitrogen (CN) defect complex is lower than that of the C{sub i}. As a result, with nitrogen doping, the carbon-impurity concentration would be high. In the insulator or p-type ZnO films, the CN defect complexes have 1+ charge state. Therefore, the existence of carbon in the ZnO:N film could be another possible passivation factor to the nitrogen acceptor, in addition to hydrogen.},
doi = {10.1116/1.2167981},
journal = {Journal of Vacuum Science Technology. A, Vacuum, Surfaces, and Films},
number = 5, September 2006,
volume = 24,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}