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

Journal Article · Sun Jan 01 04:00:00 EST 2006 · Journal of Vacuum Science Technology. A, Vacuum, Surfaces, and Films

DOI:https://doi.org/10.1116/1.2167981· OSTI ID:978487

Li, X; Asher, S E; Limpijumnong, S; Zhang, S B; Wei, S -H; Barnes, T M; Coutts, T J; Noufi, R

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.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO.
• Sponsoring Organization: USDOE
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 978487
• Journal Information: Journal of Vacuum Science Technology. A, Vacuum, Surfaces, and Films, Journal Name: Journal of Vacuum Science Technology. A, Vacuum, Surfaces, and Films Journal Issue: 5, September 2006 Vol. 24
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BINDING ENERGY
CARBON
CHARGE STATES
DEFECTS
DEPOSITION
HYDROGEN
INTERSTITIALS
Materials Science and Semiconductors
NITRIC OXIDE
NITROGEN
OXYGEN
PASSIVATION
SPECTROSCOPY
Solar Energy - Photovoltaics
THIN FILMS
X-RAY PHOTOELECTRON SPECTROSCOPY