Xiaxi Yang

Enhanced field emission from ZnO nanotetrapods on a carbon nanofiber buffered Ag film by screen printing

Field emission properties of screen-printed ZnO nanotetrapods on a carbon nanofiber buffered Ag electrode were studied. The turn-on electric field (at a current of 0.1 μA/cm2) and maximum emission current are 0.6 V/μm and 2.8 mA/cm2 (at a field of 2.2 V/μm), which were significantly improved compared to the control device made of ZnO nanotetrapods on Ag directly without a carbon nanofiber buffer. The improved field emission is due to the better contact (both mechanical and electrical) formed with a carbon nanofiber buffer.

High efficiency surface-conducted field emission from a ZnO nanotetrapod and MgO nanoparticle composite emitter

We report a surface-conducted field emitter made of a ZnO nanotetrapod and MgO nanoparticle composites with a high emission efficiency (∼100%) and current (3.77 mA at a gate voltage of 100 V and anode voltage of 1800 V). The fabrications of the triode structure with a 10×10pixel array and corresponding driving method have been proposed. The electron trajectories are simulated according to the structure. Individual pixel addressing can be achieved by a sequential scanning mode. Display of moving images employing this triode structure was demonstrated. The results are of significance to the development of ZnO based triode field emitters.

CNT-FED Architecture Based on a Gate Electrode of Diabolo Mode

Summary form only given. Recently, the carbon nanotube field emission display has drawn more and more concern. With its excellent image display quality and low fabrication expense, the printable CNT-FED will take the place of cathode ray tube as the major consumer-priced and mass-market display. A normal CNT-FED device is composed of the CNT cathode, the gate electrode, the anode and dielectric insulator layers. The gate electrode in CNT-FED is used to modulate and address the electron beam. Because some electrons may be collected by the gate electrode in a triode, the brightness of the image is decreased. This paper proposes a novel gate structure fabricated on a glass plate with diabolo funnels. Chemical corrosion was utilized to produce diabolo funnels in the glass dielectric layer and HF with the 40% concentration with sulfuric acid is used. A metal layer was screen-printed on the lower surface of the glass-mesh plate as an electron extraction gate electrode. MgO film was vaporized on the surface of the diabolo funnels. The electrons from CNT are transported in a diabolo mode via secondary electron emission over the wall of the diabolo funnel placed above the sub emitters. As a result, many electrons including the secondary electrons and backscatters are generated and the brightness of the diabolo mode gate structure CNT-FED could increase obviously. In the paper, we give the results of numerical simulation of the secondary electron emission process with Monte Carlo method. In this paper, we also study the influence of a MgO layer on the surface of the diabolo funnel. Comparisons are made between a bare glass diabolo funnel and a MgO layer coated on the surface of the funnel. As the simulation results and experiment results shown, the triode structure in which a MgO layer is vaporized on the surface of the funnel can get higher brightness

Effect of ion bombardment on the field emission property of tetrapod ZnO

The influences of ion bombardment on the field emission performance of tetrapod ZnO nanostructures are reported. As the scanning electron microscopy images and photoluminescence spectrum show, the tips of the field emitters are destroyed and the surface state of the field emitters is also changed after the ion bombardment. The ion bombardment has a considerable effect on the field emission properties of the tetrapod ZnO field emitters. After Ar+ ion bombardment with the energy of 3 keV and the ion current of 0.05 μA for 30 min, the turn-on field increases about 63% and the threshold field increases about 77%, respectively. There are two main reasons for the variation in field-emission property: (1) the decrement of the field enhancement factor β, which is caused by the variation in morphology of field emitter; (2) the increment of work function φ, which is caused by the changed concentration of the surface oxygen vacancy.

Investigation of ZnO Nanotetrapod and MgO Hybrid Field Emitter

In this letter, we report a new kind of hybrid field emitters with a mixture of ZnO nano-tetrapods and MgO particles by a spin-coating method. Due to the excellent field-emission properties of hybrid field emitters, the turn-on electric field (at a current density of 1 ¿A/cm2) and the threshold electric field (at a current density of 1 mA/cm2) have been reduced to 0.6 and 0.92 V/¿m, respectively. The turn-on and the threshold electric fields have been decreased by about 67% and 74% compared with the data reported previously. With these hybrid field emitters, a cathodoluminescent lamp is investigated. As the experimental results show, the operation voltage of the cathodoluminescent lamp is low, and the ratio between the anode and the cathode currents is quite high. Apart from this, the brightness uniformity of the lamp is also improved.

Stable field emission from screen-printed ZnO-tetrapod emitters

This article describes a study on field emission properties of ZnO tetrapods, which were synthesized by rapid heating metal zinc pellets at 900°C in air. A diode configuration with a screen-printed cathode was used to measure the field emission properties of the ZnO emitters. A low turn-on field of 1.86V∕μm at a current density of 1μA∕cm2 was obtained, while the emission current density reached 1mA∕cm2 at an applied field of 4.15V∕μm and showed no saturation. The field emission of the ZnO-tetrapod sample was recorded for 20h: no degradation of the emission current was observed in this period, while the fluctuations of the emission current were less than 3%. These experimental results indicate that ZnO tetrapods are a promising cold cathode for low cost field emission displays using screen printing.

Evaporation of Tetrapod ZnO Nanostructures and Its Influence on the Field-Emission Performance

The ZnO cathode is a promising electron source due to its excellent field-emission performance. In this letter, we investigate the evaporation characteristics of the field emitters in a screen-printed ZnO cathode by a quadrupole mass spectrometer, energy-dispersive X-ray, and scanning electron microscopy. As the experiments show, the oxygen and zinc start to be evaporated if the temperature is higher than 1273 K. The quantity of evaporative materials increases with the increment of temperature, and the quantity of evaporated oxygen is much larger than that of zinc. The evaporations of oxygen and zinc have considerable effects on the field-emission properties of the ZnO cathode, particularly the turn-on field, the threshold electric field, and the emission current density. Therefore, the evaporation of field emitters is an important factor for the stability of the field-emission current.

Architecture of field emission display based on a gate electrode of diabolo mode

In the normal gate carbon nanotube field emission display (CNT-FED), the gate electrode is used to modulate and address the electron beam. This article proposes a novel gate architecture made on a glass substrate with diabololike funnels. Chemical corrosion was utilized to produce diabolo funnels in the glass dielectric layer. A metal layer was screen printed on the lower surface of the glass-mesh plate as an electron extraction gate electrode. MgO film was vaporized on the wall of the diabolo funnels. The electrons from CNT are transported in a diabolo mode via secondary electron emission over the wall of the diabolo funnel placed above the subemitters. As a result, electrons including the secondary electrons and backscatters are generated and the brightness of the diabolo mode gate architecture CNT-FED could increase obviously.

Synthesis of Tetrapodlike Zinc Oxide Nanostructures by Inductive Heating

The inductive heating method is used to synthesize regular tetrapodlike zinc oxide nanostructures on a glass substrate. The morphology of tetrapodlike ZnO nanostructures is investigated by scanning electron microscopy. It is found that the tetrapodlike ZnO structure fabricated by inductive heating is smaller than that fabricated by PVD. Therefore, more emission sites can be generated with the tetrapodlike ZnO structures obtained by inductive heating. The field-emission characteristics of ZnO nanostructures are also measured in this letter. The measurement results show that the tetrapodlike ZnO nanostructures obtained by the inductive heating method have low turn-on electric field and high emission current. Its field-emission performance is better than that of the tetrapod ZnO emitters obtained by PVD due to its good morphology and adhesion on substrate. Because ZnO nanostructures can grow directly on a glass substrate with the inductive heating method, it is very useful for the application in the field-emission display panel.

Growth mechanism and field emission properties of inject-like ZnO nanostructure

We report the fabrication process of injector-like ZnO nanostructures and their excellent field emission properties. Injector-like Zinc oxide (ZnO) nanostructures were synthesized on a Si (001) substrate with ~5 nm thick gold film by direct thermal evaporation of Zinc power under a low temperature of 600 degC and normal pressure. Field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), Raman and photoluminescence (PL) were applied to study the structural characteristics and optical properties of the product.