Field Emission Properties of Large Area Carbon Nanotube Cathodes in DC and Pulse Modes
- PDF / 2,570,790 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 47 Downloads / 219 Views
1081-P15-07
Field Emission Properties of Large Area Carbon Nanotube Cathodes in DC and Pulse Modes
Qingliang Liao1, Yue Zhang1, Liansheng Xia2, Junjie Qi1, Yunhua Huang1, Zi Qin1, Ya Yang1, and Zhanjun Gao1 1
State Key Laboratory for Advanced Metals and Materials, Department of Materials Physics, University of Science and Technology Beijing, Beijing, 100083, China, People's Republic of 2
Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang, 621900, China, People's Republic of
ABSTRACT A large area carbon nanotube cathode was fabricated by use of a screen printing method. The emission properties of the cathode were investigated in both direct current and pulse mode experiments. In the direct current mode, the cathode has high field enhancement factor and high emission current density. In the double-pulse mode, the emission current density can approach 267 A/cm2 at an applied electric field of 15.4 V/um. Steady intense electron beams were obtained from the cathode. The results proved that the emission mechanism of CNTs at pulse electric field is plasma-induced field emission. The carbon nanotube cathode is suitable for not only field emission display applications but also high-power microwave device applications. INTRODUCTION Carbon nanotubes (CNTs) have attracted considerable attention for their potential use in the field of emission applications due to their nanometer scale, high aspect ratio, superior mechanical strength, good conductance and high chemical stability [1, 2]. CNT cathodes have realized their application in a variety of devices aiming at field emission applications [3, 4]. There have been many reports on the field emission of CNTs which were subjected to direct current (DC), and the field emission current up to tens of mA/cm2. Research toward the development of flat panel displays and scanning microscope probes has shown the CNTs are able
to carry very high local current densities of about 105 A/cm2 [5]. Recently, current densities as high as 4 A/cm2 have been reported [6]. However the current density cannot meet the requirement of intense-current sources. It is well known that application of a high-voltage (HV) pulse between a cathode and an anode leads to high-current electron beams. Therefore, it is very interesting to study the emission behavior of CNTs subjected to a pulsed electric field. In this paper, we have measured the emission characteristics of CNT cathode fabricated by screen-printing method in both DC and pulse mode experiments. The emission mechanism of CNTs at pulse electric field was studied. In different mode experiments, the CNT cathode has good field emission properties. EXPERIMENTAL DETAILS Multi-walled carbon nanobubes synthesized by the thermal CVD method were used as the field emission materials. Purified CNTs were mixed with different kinds of organic binders and were dispersed with an ultrasonic dispersion machine for 60 minutes. The paste was screenprinted on a silicon substrate with two inches in diameter, and dried at 80 °C for 20 min. A sin
Data Loading...
