Investigation of the Effect of Structural Properties of a Vertically Standing CNT Cold Cathode on Electron Beam Brightness and Resolution of Secondary Electron Images.

Alfi Rodiansyah,Kyu Chang Park,Joonwon Lim,Ha Rim Lee,Boklae Cho,Da Woon Kim

doi:10.3390/nano11081918

Abstract

Carbon nanotube (CNT)-based cold cathodes are promising sources of field emission electrons for advanced electron devices, particularly for ultra-high-resolution imaging systems, due to their high brightness and low energy spread. While the electron field emission properties of single-tip CNT cathodes have been intensively studied in the last few decades, a systematic study of the influencing factors on the electron beam properties of CNT cold cathodes and the resolution of the secondary electron images has been overlooked in this field. Here, we have systematically investigated the effect of the structural properties of a CNT cold cathode on the electron beam properties and resolution of secondary electron microscope (SEM) images. The aspect ratio (geometric factor) and the diameter of the tip of a vertically standing CNT cold cathode significantly affect the electron beam properties, including the beam size and brightness, and consequently determine the resolution of the secondary electron images obtained by SEM systems equipped with a CNT cold cathode module. Theoretical simulation elucidated the dependence of the structural features of CNT cold cathodes and electron beam properties on the contribution of edge-emitted electrons to the total field emission current. Investigating the correlations between the structural properties of CNT cold cathodes, the properties of the emitted electron beams, and the resolution of the secondary electron images captured by SEM equipped with CNT cold cathode modules is highly important and informative as a basic model.

Highlights

Field emission electron sources have attracted enormous research attention in the field of electron emission and electron devices, due to their inherent merits, including high brightness, coherence, and low energy spread [1,2,3,4,5]
The basic field emission characteristics were measured in the diode structure with the phosphor anode for evaluation of the Carbon nanotube (CNT) cold cathode
We investigated the effect of the structural properties of CNT cold cathodes on the electron beam properties and resolution of secondary electron images

Summary

Introduction

Field emission electron sources have attracted enormous research attention in the field of electron emission and electron devices, due to their inherent merits, including high brightness, coherence, and low energy spread [1,2,3,4,5]. The small radius of curvature of the tip of CNT cold cathodes induces a substantial field enhancement effect and decreases the operating voltage of the field emission devices. It is beneficial for a miniaturized electron emission source to be able to be driven stably up to few micro-amperes of current [15,16,17,18,19,20]. Despite the suitable features of CNTs for high-performance cold cathodes, there

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Conclusion