Triode field emitters with planar carbon-nanoparticle cathodes Kyung Ho Park, Sungil Bae, Soonil Lee * , Ken Ha Koh Department of Molecular Science and Technology, Ajou University, Suwon 442-749, Republic of Korea Received 4 September 2004; received in revised form 23 March 2005 Available online 15 August 2005 Abstract We designed and fabricated three different types of triode field emitters with planar carbon-nanoparticle (CNP) cathodes such as a normal-gate structure, a double-gate structure, and a well-structure. A normal-gate structure CNP triode emitter showed good field emission properties. The field emission started at the gate-voltage of 45 V, and the anode current reached the level of 120 nA at the gate-voltage of 60 V. However, in general, normal-gate structure suffered from large gate current. Using the dou- ble-gate structure, we successfully reduced the gate current to the level less than 4% of anode currents up to the anode current of 250 nA. To simplify fabrication process while maintaining the gate current reduction effect of the double-gate structure, a triode emitter with a well-structure cathode was fabricated via reactive-ion etching of a heavily doped n-type silicon wafer. The triode emit- ter with a well-structure cathode and a recessed gate structure showed negligible gate current. Ó 2005 Elsevier B.V. All rights reserved. PACS: 85.45.Db; 81.05.Uw Keywords: Triode field emitter; Carbon-nanoparticles; Double-gate structure; Well-structure 1. Introduction Triode field emitters have many advantages in practi- cal applications; for example, low driving voltage, high resolution, and full gray-scale imaging are possible only in triode-type field emission display. In particular, triode emitters with planar cathodes have become attractive because of their advantages, including the substantial reduction in manufacturing cost, over tip-array cath- odes. Therefore, during the last few years, many groups have vigorously tried to fabricate triode-type field emit- ters incorporating various carbon based films with excel- lent electron emission characteristics as cathodes [1–9]. Carbon-nanotubes emerged as one of the promising electron emitters due to their natural structure that could give large electric field enhancement. However, as it turned out, it was particularly hard to fabricate tri- odes with the normal-gate structure using carbon-nano- tube films as cathodes, and only few groups succeed in demonstrating gate controlled emission from nano- tube–cathode triodes [6–9]. This difficulty arose mainly from the peculiar structural trait of nanotubes; they were typically long and very flexible, and, therefore, sus- ceptible to cathode-gate short or to a huge gate current. Previously, we reported an excellent electron emission from carbon-nanoparticle (CNP) films [10]. CNP film consisted of uniformly distributed CNPs with diameters in the range of 100–200 nm, and each CNP consisted of carbon layer encapsulating metal (or carbide) cores. Since, CNP films reveal smooth surface morphology, in addition to the excellent emission properties, CNP films are suitable as cathode material for triode field emitters with planar cathodes. The details of CNP syn- thesis, structure, and its field emission properties were presented elsewhere [10]. In this work, we report the fab- rication and operation results of three different types of triode field emitters with planar CNP cathodes. 1567-1739/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.cap.2005.07.017 * Corresponding author. E-mail address: soonil@ajou.ac.kr (S. Lee). www.elsevier.com/locate/cap www.kps.or.kr Current Applied Physics 6 (2006) 1048–1053