Microelectronic Engineering 61–62 (2002) 475–483 www.elsevier.com / locate / mee Study of multi-walled carbon nanotube structures fabricated by PMMA suspended dispersion a, b b a b * S.-B. Lee , K.B.K. Teo , M. Chhowalla , D.G. Hasko , G.A.J. Amaratunga , b a W.I. Milne , H. Ahmed a Microelectronics Research Centre, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB30 HE, UK b Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB21 PZ, UK Abstract We report on the electrical characteristics of plasma enhanced chemical vapour deposition (PECVD)-grown, multi-walled carbon nanotube (MWCNT) devices made by a new fabrication method, PMMA suspended dispersion. This method makes it possible to suspend nanotubes between metal electrodes and to remove unwanted nanotubes from the substrate. The measurements show that the MWCNTs are metallic and able to 6 2 maintain a current density | 2 3 10 A/cm for more than 15 days with a maximum current density of 7 2 | 1.8 3 10 A / cm . This high current density and reliability will make PECVD-grown MWCNTs applicable to field emission cathodes.  2002 Elsevier Science B.V. All rights reserved. Keywords: Multi-walled carbon nanotubes; Plasma enhanced chemical vapour deposition; PMMA suspended dispersion; Field emission cathode 1. Introduction The remarkable properties of carbon nanotubes (CNTs) [1,2] have generated considerable interest for their use in numerous applications. Various experiments have shown that CNTs have superior mechanical strength [3], unique transport characteristics [4,5], and a high aspect ratio [1]. These unique properties of CNTs make them suitable candidates for applications such as scanning probe tips [6], nanoscale transistors [7,8], and field emission cathodes [9]. The CNTs used in these devices were prepared by various techniques, namely arc-discharge [1], laser ablation [10] and chemical vapour deposition (CVD) [11]. The latter technique allows precise control of the location of where the nanotubes are grown. This is done by using a catalyst-mediated growth process with lithographically *Corresponding author. E-mail address: sbl22@cam.ac.uk (S.-B. Lee). 0167-9317 / 02 / $ – see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0167-9317(02)00436-7