Jingfang Xu

ZnO/Zn phosphor thin films prepared by IBED

Abstract ZnO/Zn phosphor thin films were prepared by ion-beam-enhanced deposition (IBED). Post-deposition annealing of these films was performed at temperatures from 100 to 1000°C in a N 2 atmosphere. RBS, XRD and PL spectra were employed to characterize these films. It was detected that there is a large amount of excess Zn in the prepared films. An amorphous structure was found in the films deposited without ion bombardment, and simultaneous ion bombardment could cause the films to contain crystalline phases and even greater excess Zn. The PL spectra showed that UV/violet and blue/green luminescence was excited in ZnO/Zn films. The annealing strongly affected the visible luminescence. Possible reasons may include the recovery of structural defects, homogenization, and evaporation of excess Zn with different contributions at different temperature ranges.

Characteristics of ZnO : Zn phosphor thin films by post-deposition annealing

Abstract ZnO:Zn phosphor thin films were prepared by ion beam assisted deposition (IBAD). Post-deposition annealing of these films was performed at temperature from 100°C to 1000°C in N2 and air, respectively. Several analysis techniques were employed to characterize their composition, structure and photoluminescence. Two different bands of luminescent peaks, which are UV/violet (380–420 nm) and blue/green (470–530 nm) luminescence, were found in the PL spectra of these films. The results show that the intensity of the blue/green light is strongly affected by the temperature of annealing which may result from the recovery of structural defects, the homogenization and the evaporation of excess Zn. However, the contributions of these processes are different at different temperature ranges. We also find that the films annealed in N2 ambient show stronger luminescent intensity than those in air ambient.

Enhanced electron field emission properties of diamond-like carbon films using a titanium intermediate layer

Substantially improved uniformity and enhanced electron field emission properties of hydrogen-free diamond-like carbon (DLC) films were obtained using a titanium intermediate layer after the annealing process. Large emission current densities of 2.08 mA cm-2 at 14.3 V µm-1 and 7.20 mA cm-2 at 25.7 V µm-1 were achieved for DLC/Ti/Si film annealed at 430 °C for 0.5 h. Its field emission was much more uniform than that of as-prepared DLC/Ti/Si and DLC/Si films. Secondary ion mass spectroscopy (SIMS) showed that C has been amply diffused into the Ti layer. An x-ray photoelectron spectroscopy (XPS) spectrum of the annealed DLC/Ti/Si film after 10 min of argon ion sputtering showed the formation of TiC at the interface between the DLC and Ti/Si substrate. This interaction and interdiffusion of C and Ti could significantly lower the Schottky barrier height between the DLC and Ti/Si substrate. The result was that electrons induced from the Ti/Si substrate can be easily penetrated into DLC films, which enhances the field emission properties.

Memory emission of printed carbon nanotube cathodes

The memory emission (ME) effect of printed carbon nanotube cathodes (PCNTCs) was reported. If the surface of PCNTCs is marked in a pattern by some methods, the emission image of this cathode will be the figure of the same pattern, just like the PCNTCsremember what happened in the past. We named this phenomenon as “memory emission.” According to the finding of field emission scanning electron microcopy, we suggested that the connecting CNT bundles protruding to the substrate and the electron conductive probability increasing from the substrate to the topside CNT emitter, which result in the emission enhancement of the marked place, were the reasons of the ME effect of PCNTCs. With the help of the ME effect of PCNTCs, the well-patterned emission image could easily be obtained.

Effect of annealing on electron field emission properties of hydrogen-free amorphous carbon films

In this paper, a series of 200-nm-thick, hydrogen-free, amorphous carbon (a-C) films deposited on heavily doped Si (111) by filtered arc deposition (FAD) were isothermally annealed at 200, 400, 600, 800, and 1000°C for 30 min. Electron field emission from these films was studied by using a diode structure device. It was shown that field emission properties of the films were degraded with increasing annealing temperatures. But after being annealed at 800°C for 30 min, the a-C film showed enhanced field emission properties compared with the unannealed a-C film. Atomic force microscopy (AFM) showed that a-C film annealed at 800°C had dense protrusions on the surface. It was shown that annealing can have a remarkable effect on field-emission properties of the a-C films.

Electron field emission from nitrogen-containing diamond-like carbon films deposited by filtered arc deposition

Abstract In this paper, electron field emission properties and fluorescent displays of 300 nm thick nitrogen-containing diamond-like carbon (DLC:N) films are reported. The films were deposited on to highly n -doped Si (111) substrates by filtered arc deposition (FAD) with different N 2 partial pressures (0.01, 0.05, 0.1 Pa) in the deposition chamber. Their electron field emission properties were studied using a simple diode structure. It was shown that the DLC:N film possessed enhanced field emission properties when a N 2 pressure of 0.05 Pa was used. Emission current of 0.1 μA was detected under the electric field of 8.1 V/μm. An emission current density of 0.204 mA/cm 2 was obtained under 17.8 V/μm.

Electron Field Emission from Different sp3 Content Diamond-Like Carbon Films

Different sp3 content diamond-like carbon films are deposited on to highly n-doped Si(111) substrates by a new plasma deposition technique-filtered arc deposition. Their electron field emission properties are studied by using a simple diode structure. It is showed that the turn-on field is decreased and field emission current density is increased with the increasing sp3 content (75-80%, 80-83%, and 88-90%) of the films. Field emission current of 0.1 μA from the three samples was detected under the electric field of 10.1, 5.6, and 2.9 V/μm and emission current density of 4.4, 15.2, and 43.2 μA/cm2, respectively, under 14.3 V/μm. Fowler-Nordheim (F-N) plots of the three samples nearly show of lineaity indicating that electron field emission obeys F-N theory.

Surface Modification Of Printed Carbon Nanotubes And Its Application Of Field Emission

A surface-modified carbon nanotubes (CNTs), which shows an excellent electron field emission property was obtained in the present work. Conventional screen-printing technology was applied to prepare the CNT films. After hydrogen plasma surface treating process, the morphology of nanotubes surface were totally changed. Those modified CNTs exhibited low turn-on electron field of 0.98 V/μm, current density of 1 mA/cm2 at a field of 6.53 V/μm and a very high emission site density of about 106/cm2, which is three orders of magnitude higher than that of untreated CNT films. Diode-type prototype devices were obtained which proved the modified CNTs is suitable for field emission displays.

High sp(3) content hydrogen-free amorphous diamond: an excellent electron field emission material

Details are given of a study of the characteristics of field-induced electron emission from hydrogen-free high sp3 content (>90%) amorphous diamond (a-D) film deposited on heavily doped (ρ<0.01ω·cm) n-type monocrystalline Si (111) substrate. It is demonstrated that a-D film has excellent electron field emission properties. The emission current can reach 0.9 μA at applied field as low as 1 V/μm, and the emission current density can be about several mA/cm2 under 20 V/μm. The emission current is stable when the beginning current is at 50 μA within 72 h. Uniform fluorescence display of electron emission from the whole face of the a-D film under the electric field of 10–12 V/μm is also observed. The contribution of excellent electron emission property results from the smooth, uniform, amorphous surface and high sp3 content of the a-D film.

Improved electron emission properties of screen-printed carbon nanotube film by hydrogen plasma surface treatment

Tao Feng*, Jihua Zhang, Xi Wang, Xianghuai Liu, Shichang Zou Ion Beam Laboratory, Shanghai Institute of Mircosystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, Peoples Republic of China Phone: +86-21-62511070-8923, E-mail: tfeng@itsvr.sim.ac.cn Qiong Li, Jingfang Xu Department of Electronics Science and Technology, East China Normal University, Shanghai 200062, Peoples Republic of China