Chaogang Lou

A Stable Field-Emission Light Source With ZnO Nanoemitters

A field-emission cathode is fabricated with ZnO tetrapodlike nanoemitters. With a simple planar triode structure, a cathodoluminescent light source has been investigated. Because of the characteristics of surface-conduction electron-emission planar triode, this cathodoluminescent light source shows a very good performance. As experimental results show, the turn-on electric field is about 1 V/mum, whereas the current density is 1 muA/cm2. The threshold electric field is 1.6 V/mum, whereas the current density is 1 mA/cm2. When a pulse voltage with 4% duty cycle is applied on the gate electrode, the fluctuation of anode current is smaller than 15 % during 200 h.

An Improved Planar Triode With ZnO Nanopin Field Emitters

In this letter, an improved planar triode with ZnO nanopin field emitters has been proposed. Comparison with a conventional planar triode, a layer of ZnO nanostructures is deposited between the cathode and gate electrode. These ZnO nanostructures are used as field emitters. Because both electrodes and ZnO layer can be deposited with screen-printing method, the fabrication process of an improved planar triode is quite simple. As experimental results shown, the turn-on voltage and the threshold voltage are low. The swing voltage is about 120 V when the anode current of a single pixel is 200 nA. A good focus performance is also obtained with a new electrode-pattern in the planar triode.

High-current-density field emission from multiwalled carbon nanotubes by chemical-vapor deposition with effective aging treatment

Carbon nanotubes have been grown on silicon substrates coated with nickel-catalyst films by chemical-vapor deposition using mixtures of acetylene and nitrogen. An effective aging treatment was carried out before the field-emission measurement of carbon-nanotube samples. The results show that the turn-on field is 1.8V∕μm at 2μA emission current and that the highest emission current of 13mA at the electrical field of 23V∕μm. This corresponds to the field-emission current density of 414mA∕cm2. Some discussions about the long growing time of carbon nanotubes, the aging process, and high-current field emission are given.

Study of electric field distribution on a vertically-standing single-walled carbon nanotube emitter irradiated by femtosecond laser pulses

Ultrafast pulsed electron sources enable the amazing applications including the time-resolved electron microscopy, ultrafast X-ray sources, guided electron interferometer, ultrafast Analog-to-Digital converter and et al. Recent published research papers have described nanometric ultrafast electron sources which are metal nanotips irradiated by ultrafast laser beam [1–5]. Some researchers believe that the laser driven ultrafast electron emission from metal nanotips is related to thermionic emission, optical field emission and multiphoton emission. The nature of the laser driven ultrafast electron emission is not so clear to date. However, experimental data show that optical field emission process is real.

Efficient field emission of carbon nanotubes grown on a copper substrate

Carbon nanotubes have been grown on a polished copper substrate by thermal chemical vapor deposition (CVD). Nickel film is deposited on the metallic substrate as catalyst and the reactant gas is acetylene. Efficient field emission of CNTs emitters (Emission area is about 3.14 mm2) is observed from I-V and F-N curves. Stable emission current with the density of more than 20mA was got at the electric field of 2.87V/um. SEM and TEM were used to characterize the morphologies of carbon nanotubes.

Analysis of the driving characteristic of carbon nanotube triode with high frequency

A circuit model is proposed to analyze the driving characteristics of the carbon nanotube field emission triode. In the model, the current gain magnitude, the cutoff frequency, and the transition frequency can be calculated, and the result is confirmed by PSPICE simulation. In addition, the parameters that affect the cutoff frequency and the transition frequency are discussed, which include capacities, inductances, and transconductance. The influence of the traverse time of electrons on the triode’s frequency performance will play an important role in the range of very high frequency.

Field Emission From the Carbon Nanotube Cathode Fabricated by Powder Metallurgical Method

Traditional powder metallurgical method is used to fabricate the cold field emission cathodes. Copper powder and nano-copper oxide powder are mixed with carbon nanotubes, respectively, then pressed and sintered to form two kinds of bulk cathodes. The measurement results show that cathodes fabricated by this method have typical I-V curve and F-N curve

Analysis of the Driving Characteristic of CNT Triode with High Frequency

The driving characteristic of a carbon nanotube field emission triode is analyzed using RF-PSPICE model. A circuit model of the triode is proposed

Influence of Catalyat Film Thickness on Carbon Nanotubes

In this paper, the effects of catalyst film thickness on the field emission currents and the emission stability of carbon nanotubes (CNTs) are presented. The CNTs are grown on Ni catalyst films of different thickness (20 nm, 50 nm, 70 nm) by chemical vapor deposition (CVD). Results show that the CNTs grown on 20 nm catalyst films have a poorer field emission and poorer emission stability than those of 50 and 70 nm catalyst films

Large Current Emission from CNTs Cold Cathode

Carbon nanotubes (CNTs) have attracted great interest in the scientific field because of their unique structure, remarkable properties and potential applications. CNTs have been synthesized by methods such as arc discharge, chemical vapor deposition, laser ablation, etc. Such sustained, high-current field emission is necessary for many technological applications: for example, flat-panel field-emission displays require 10 mA/cm2, while microwave power amplifier tubes require at least 400 mA/cm2. These high-current density levels were previously obtainable only by thermionic emission above 1000 K, or lithographically fabricated tips. Field emission has been reported from other forms of carbon, however, at lower current densities (0.3 mA/cm2 for graphite, 30 mA/cm 2 for diamond)