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Evolution of Granular Structure and the Enhancement of Electron Field Emission Properties of Nanocrystalline and Ultrananocrystalline Diamond Films Due to Plasma Treatment Process.
Chen, Wei-En; Chen, Chengke; Yeh, Chien-Jui; Hu, Xiaojune; Leou, Keh-Chyang; Lin, I-Nan; Lin, Chii-Ruey.
Afiliação
  • Chen WE; Department of Mechanical Engineering and Institute of Manufacturing Technology , National Taipei University of Technology , Taipei 10608 , Taiwan.
  • Chen C; College of Materials Science and Engineering , Zhejiang University of Technology , Hangzhou , Zhejiang 310027 , China.
  • Yeh CJ; Department of Engineering System and Science , National Tsing-Hua University , Hsin-Chu 30013 , Taiwan.
  • Hu X; College of Materials Science and Engineering , Zhejiang University of Technology , Hangzhou , Zhejiang 310027 , China.
  • Leou KC; Department of Engineering System and Science , National Tsing-Hua University , Hsin-Chu 30013 , Taiwan.
  • Lin IN; Department of Physics , Tamkang University , New-Taipei 25137 , Taiwan.
  • Lin CR; Department of Mechanical Engineering and Institute of Manufacturing Technology , National Taipei University of Technology , Taipei 10608 , Taiwan.
ACS Appl Mater Interfaces ; 10(34): 28726-28735, 2018 Aug 29.
Article em En | MEDLINE | ID: mdl-30053374
ABSTRACT
The present work reports the plasma post treatment (ppt) process that instigates the evolution of granular structure of nanocrystalline diamond (NCD), consequently conducing the enhancement of the electron field emission (EFE) properties. The NCD films contain uniform and nanosized diamond grains (∼20 nm) with negligible thickness for grain boundaries that is distinctly different from the microstructure of ultrananocrystalline (UNCD) films with uniformly sized ultrananodiamond grains (∼5 nm) having relatively thick grain boundaries (∼0.1 nm). The turn-on of the electron field emission (EFE) process occurs at ( E0)NCD = 24.1 V/µm and ( E0)UNCD = 18.6 V/µm for the pristine NCD and UNCD materials, respectively. The granular structure of the starting diamond films largely influenced the microstructure evolution behavior and EFE properties of the materials subject to plasma annealing. The CH4/(Ar-H2) ppt-process leads to formation of a hybrid granular structured diamond (HiDNCD and HiDUNCD) via isotropic conjoining of nanosized diamond grains, whereas the CH4/N2 ppt-process leads to the formation of acicular granular structured diamond films (NNCD and NUNCD) via inducing aeolotropic growth of nanodiamond grains. While both of the HiDNCD and HiDUNCD films contain hybrid granular structure, the HiDUNCD films contain a larger proportion of nanographite phase and result in improved EFE properties, viz. ( E0)HiD-UNCD = 7.7 V/µm and ( E0)HiD-NCD = 12.3 V/µm. In contrast, when the films were CH4/N2 ppt-processed, the acicular diamond grains were formed for NUNCD and NNCD films; however, carbon nanoclusters attached to the diamond grains of NNCD films and the nanographitic layers encasing diamond cores are not crystallized very well, as compared with NUNCD films. Therefore, the NNCD films exhibit slightly inferior EFE properties than the NUNCD films, viz. ( E0)N-UNCD = 5.3 V/µm and ( E0)N-NCD = 11.8 V/µm. The difference in EFE properties for ppt-processed NCD and UNCD films corresponds to the dissimilar granular structure evolution behavior in these films that is, in turn, due to the distinct different microstructure of the pristine NCD and UNCD films.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2018 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2018 Tipo de documento: Article