期刊
JOURNAL OF APPLIED PHYSICS
卷 109, 期 5, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3556741
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资金
- National Natural Science Foundation of China [50972129, 50602039]
- Qianjiang talent project of Zhejiang province of China [2010R10026]
Ultrananocrystalline diamond (UNCD) films were implanted by oxygen ion and annealed at different temperatures. The electrical and structrual properties of O+-implanted UNCD films were investigated by Hall effects, high-resolution transmission electron microscopy (HRTEM) and uv Raman spectroscopy measurements. The results show that O+-implanted nano-sized diamond grains annealed at 800 degrees C and above give n-type conductivity to the sample and the UNCD film exhibits n-type resistivity with the carrier mobility of 1 similar to 11 cm(2) V-1 s(-1). With O+ dose increasing from 10(15) to 10(16) cm(-2), diamond phase transits to the amorphous carbon phase accompanied by n-type semiconduction transforming to metallic conduction. In the 10(14) cm(-2) O+-implanted UNCD film, some amorphous carbon at grain boundaries transits to diamond phase with annealing temperature (T-a) increasing from 500 degrees C to 800-900 degrees C, and some of diamond grains are found to be converted to amorphous carbon phase again after 1000 degrees C annealing. This phase transition is closely relative to the n-type conductivity of the UNCD films, in which n-type conductivity increases with the amorphous carbon phase transiting to diamond phase in the T-a range of 500-900 degrees C, and it decreases with diamond phase transiting to amorphous carbon phase in the case of 1000 degrees C annealing. It is indicated that the O+-implanted nano-sized diamond grains dominantly control the n-type conductivity of UNCD film in the Ta range of 800-900 degrees C, while the grain-boundary-conduction controls the n-type conductivty in UNCD film annealed at 1000 degrees C. In this case, a novel conduction mechanism that O+-implanted nano-sized diamond grains supply n-type conductivity and the amorphous carbon grain boundaries give a current path to the UNCD films is proposed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3556741]
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