The 3D-tomography of the nano-clusters formed by Fe-coating and annealing of diamond films for enhancing their surface electron field emitters

• Published in: AIP advances Vol. 2; no. 3; pp. 032153 - 032153-17
• Main Authors: Chen, Huang-Chin, Lo, Shen-Chuan, Lin, Li-Jiaun, Huang, Pin-Chang, Shih, Wen-Ching, Lin, I-Nan, Lee, Chi-Young
• Format: Journal Article
• Language: English
• Published: AIP Publishing LLC 01.09.2012
• Subjects: Annealing; Clusters; Diamond films; Diamonds; Iron; Nanocomposites; Nanomaterials; Nanostructure
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/1.4748865

The Fe-coating and H2-annealed processes markedly increased the conductivity and enhanced the surface electron field emission (s-EFE) properties for the diamond films. The enhancement on the s-EFE properties for the diamond films is presumably owing to the formation of nano-graphite clusters on the surface of the films via the Fe-to-diamond interaction. However, the extent of enhancement varied with the granular structure of the diamond films. For the microcrystalline (MCD) films, the s-EFE process can be turned on at (E0)MCD = 1.9 V/μm, achieving a large s-EFE current density of (Je)MCD = 315 μA/cm2 at an applied field of 8.8 V/μm. These s-EFE properties are markedly better than those for Fe-coated/annealed ultrananocrystalline diamond (UNCD) films with (E0)UNCD = 2.0 V/μm and (Je)UNCD = 120 μA/cm2. The transmission electron microscopy showed that the nano-graphite clusters formed an interconnected network for MCD films that facilitated the electron transport more markedly, as compared with the isolated nano-graphitic clusters formed at the surface of the UNCD films. Therefore, the Fe-coating/annealing processes improved the s-EFE properties for the MCD films more markedly than that for the UNCD films. The understanding on the distribution of the nano-clusters is of critical importance in elucidating the authentic factor that influences the s-EFE properties of the diamond films. Such an understanding is possible only through the 3D-tomographic investigations.