Microstructure of ultrananocrystalline diamond films grown by microwave Ar{endash}CH{sub 4} plasma chemical vapor deposition with or without added H{sub 2}
Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar{endash}1%CH{sub 4} or Ar{endash}1%CH{sub 4}{endash}5%H{sub 2}, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2{endash}10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H{sub 2}. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2{endash}0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on the Si substrate when H{sub 2} is present in the plasma. For the case of UNCD growth from a plasma without addition of H{sub 2}, the initial nucleation occurs on an amorphous carbon layer about 10{endash}15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial. {copyright} 2001 American Institute of Physics.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40204339
- Journal Information:
- Journal of Applied Physics, Vol. 90, Issue 1; Other Information: DOI: 10.1063/1.1377301; Othernumber: JAPIAU000090000001000118000001; 084113JAP; PBD: 1 Jul 2001; ISSN 0021-8979
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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