CARBON NANOTUBE LATERAL FIELD EMITTERS WITH METALLIC ANODE

摘要

In 1961, the concept of lateral field emission devices fabricated utilizing semiconductor microfabrication technique was proposed by Shoulders [1]. Since then, lateral field emitters utilizing various materials including NiCr [2] Si [3], W [4], TiW [5], diamond [6], and carbon nanotubes (CNTs) [7-9] as the emitters have been reported. Beside ease of fabrication comparing to "vertical-type" field emission devices, an attractive feature of lateral devices is that their capacitance is generally small (< pF) due to the small interelectrode overlapping area. Consequently, lateral devices have been studied broadly for potential high frequency operation with low threshold voltage. In this study, a novel approach of growing CNTs selectively and laterally on oxidized silicon substrate with an integrated metallic anode, utilizing a dual-mask microfabrication process, Fig. 1, is presented. The fabrication process begins with sputter-deposition of a tri-metal layer of metal/Co/Ti after the first mask patterning, Where Co and Ti are the growth catalyst and buffer layer, respectively. The thick top metal layer suppresses vertical growth of CNTs and also serves as electrical contact. In the second mask patterning, the anode pattern is aligned to the cathode such that a metallic anode can be deposited. The synthesis of the lateral CNT emitters was achieved through a two-step microwave plasma-enhanced chemical vapor deposition (MPCVD) including a pre-growth H{sub}2 plasma treatment, as described previously [10].