Field Emission Characteristics of the Structure of Vertically Aligned Carbon Nanotube Bundles.

Pao-Hung Lin,Hsin-Yueh Chang,Kuei-Yi Lee,Hsuan-Chen Chang,Wei-Jhih Su,Yi-Ting Shih,Ching-An Chen,Cong-Lin Sie

doi:10.1186/s11671-015-1005-1

Pao-Hung Lin, Hsin-Yueh Chang + Show 6 more

Open Access

https://doi.org/10.1186/s11671-015-1005-1

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Abstract

In this study, we performed thermal chemical vapor deposition for growing vertically aligned carbon nanotube (VACNT) bundles for a field emitter and applied photolithography for defining the arrangement pattern to simultaneously compare square and hexagonal arrangements by using two ratios of the interbundle distance to the bundle height (R) of field emitters. The hexagon arrangement with R = 2 had the lowest turn-on electric field (Eto) and highest enhancement factor, whereas the square arrangement with R = 3 had the most stable field emission (FE) characteristic. The number density can reveal the correlation to the lowest Eto and highest enhancement factor more effectively than can the R or L. The fluorescent images of the synthesized VACNT bundles manifested the uniformity of FE currents. The results of our study indicate the feasibility of applying the VACNT field emitter arrangement to achieve optimal FE performance.

Highlights

Since its discovery in 1991, carbon nanotube (CNT) [1] properties have been explored and examined, and several applications have been designed and developed
The performance of field emission (FE) materials determined on the basis of the Fowler–Nordheim (FN) equation [2], which describes the relation between the FE current number density, Φ, and enhancement factor β, is influenced by the nature of the material and the arrangement and surface morphology of the field emitter
The bundle was vertically aligned with the Si substrate; it consisted of vertically aligned CNTs (VACNTs) with a high number density of approximately 109 cm−2, which was examined using the magnified scanning electron microscope (SEM) image of the bottom region

Summary

Introduction

Since its discovery in 1991, carbon nanotube (CNT) [1] properties have been explored and examined, and several applications have been designed and developed. The performance of FE materials determined on the basis of the Fowler–Nordheim (FN) equation [2], which describes the relation between the FE current number density, Φ, and enhancement factor β, is influenced by the nature of the material and the arrangement and surface morphology of the field emitter. Because the materials used for various emitter fabrications are identical, the arrangement of an emitter decisively influences FE characteristics, primarily, the screening effect and the number density of the emission site. The pattern of CNT bundle arrays can be defined by using photolithography; the required catalyst metal can be deposited on the defined position. This method is simple, easy to control, and inexpensive

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