Bias-enhanced nucleation and growth of ultrananocrystalline diamond(UNCD) nano-pillars on silicon substrates by low-pressure microwave plasma chemical vapor deposition in a hydrogen-rich gas mixture with methane is reported. Direct-current biasing of the substrate in a constant-current mode is applied to substrates, which are pre-heated to 800 °C, to result in a negative bias voltage of greater than 350 V throughout the nucleation and growth process. Self-masking by UNCD clusters, angle dependent sputtering of UNCD clusters, and ion-assisted chemical vapor deposition by bias enhanced bombardment of energetic ions are attributed to the formation of UNCD nano-pillars. High-resolution transmission electron microscopy analysis indicates that an interfacial layer exists between the silicon substrate and the UNCD nano-pillars. The porous UNCDfilm with high-density nano-pillars exhibits excellent optical anti-reflectivity and improved electron field emission characteristics compared to smooth and solid UNCDfilms.
Received 13 July 2012Accepted 12 November 2012Published online 19 December 2012
This work was partially supported by Taiwan National Science Council (100-2120-M-006-001-, 100-2221-E-006-169-MY3, 101-2911-I-006-517, and 101-006-140-MY3) and Taiwan Ministry of Education. Synthesis of UNCD was carried out in Argonne National Lab by (YCC) under a collaborative agreement between National Cheng Kung University and Argonne National Lab and under the “Dragon-Gate Program” of Taiwan National Science Council.
Article outline: I. INTRODUCTION II. EXPERIMENTAL III. RESULTS AND DISCUSSION IV. CONCLUSIONS
1.A. R. Krauss, O. Auciello, D. M. Gruen, A. Jayatissa, A. Sumant, J. Tucek, D. C. Macini, N. Moldovan, A. Erdemir, D. Ersoy, M. N. Gardos, H. G. Busmann, E. M. Meyer, and M. Q. Ding, Diamond Relat. Mater.10, 1952 (2001).
23.A. R. Krauss, O. Auciello, M. Q. Ding, D. M. Gruen, Y. Huang, V. V. Zhirnov, E. I. Givargizov, A. Breskin, R. Chechen, E. Shefer, V. Konov, S. Pimenov, A. Karabutov, A. Rakhimov, and N. Suetin, J. Appl. Phys.89, 2958–2967 (2001).