Browsing by Author "Lo, Hsiang-Yu"

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Analysis of field emission of fabricated nanogap in Pd strips for surface conduction electron-emitter displays
(2008-04-01)
Lo, Hsiang-Yu
;
Li, Yiming
;
Tsai, Chih-Hao
;
Pan, Fu-Ming
;
材料科學與工程學系
We study the field emission (FE) property of a nanometer-scale gap structure in a palladium strip, which was fabricated by hydrogen absorption under high-pressure treatment. A vigorous cracking process could be accompanied by extensive atomic migration during the hydrogen treatment. A three-dimensional finite-difference time-domain particle-in-cell method is adopted to simulate the electron emission in a surface-conduction electron-emitter display (SED) device. Examinations of conducting characteristics, FE efficiency, the local field around the emitter, and the current density on the anode plate with one FE emitter are conducted. The image of a light spot is successfully produced on a phosphor plate, which implies that the explored electrode with nanometer separation possesses a potential SED application. Experimental observation and numerical simulation show that the proposed structure can be used as a surface conduction electron emitter and has a high FE efficiency with low turn-on voltage and a different electron emission mechanism. This study benefits the advanced SED design for a new type of electron source.
Effect of Process Variation on Field Emission Characteristic in Surface Conduction Electron-Emitters
(2007)
Lo, Hsiang-Yu
;
Li, Yiming
;
Chao, Hsueh-Yung
;
Tsai, Chih-Hao
;
Pan, Fu-Ming
In this work, we explore the effect of process variation on field emission characteristics in surface conduction electron-emitters. The structure of palladium thin-film emitter is fabricated on the substrate and the nanometer scaled gap is formed by the focused ion beam (FIB) technique. Different shapes of nanogaps due to the process variations are investigated by the experiment and 3D Maxwell particle-in-cell simulation. Four deformation structures are examined, and it is found that the Type 1 exhibits high emission efficiency due to a stronger electric field around the apex and larger the emission current among structures. The electron emission current is dependent upon the angle of inclination of surface.
Effect of process variation on field emission characteristics in surface-conduction electron emitters
(2008-07-01)
Lo, Hsiang-Yu
;
Li, Yiming
;
Tsai, Chih-Hao
;
Chao, Hsueh-Yung (Robert)
;
Pan, Fu-Ming
In this paper, we explore the effect of process variation on field emission characteristics in surface-conduction electron emitters. The structure of Pd thin-film emitter is fabricated on the substrate and the nanometer scale gap is formed by the focused ion beam technique. Different shapes of nanogaps due to the process variations are investigated by the experiment and three-dimensional Maxwell particle-in-cell simulation. Four deformation structures are examined, and it is found that the type I exhibits high emission efficiency due to a stronger electric field around the apex and larger emission current among structures. The electron emission current is dependent upon the angle of inclination of surface. Hydrogen plasma treatment is also used to increase the edge roughness of the nanogap and thereby dramatically improve the field emission characteristics. For the nanogap with a separation of 90 nm, the turn-on voltage significantly reduces from 60 to 20 V after the hydrogen plasma treatment.
Effects of Hydrogen Plasma Treatment on Field-Emission Characteristics of Palladium Nanogap Emitters
(2008)
Tsai, Chih-Hao
;
Chen, Kuan-Jung
;
Pan, Fu-Ming
;
Lo, Hsiang-Yu
;
Li, Yiming
Nanogaps were prepared on the Pd line electrode by focused ion beam, and electron field-emission characteristics of the Pd nanogap emitter subject to hydrogen plasma treatment were studied. The as-prepared nanogap had smooth and uniform gap edges, and thus field-emission characteristics of the nanogap emitter were primarily dependent on the gap separation. After the hydrogen plasma treatment, the field-emission property of the Pd nanogap emitter was significantly enhanced. The improvement in the field-emission property was mainly attributed to formation of a ragged morphology on the nanogap emitter during the hydrogen plasma treatment. The ragged morphology provided more emitting sites with a high field enhancement factor. The Fowler-Nordheim plot was used to elucidate the dependence of field-emission characteristics of the Pd nanogap emitter on the plasma-induced ragged morphology. (C) 2008 The Electrochemical Society. [DOI: 10.1149/1.2988646] All rights reserved.
Emission Efficiency Dependence on the Tilted Angle of Nanogaps in Surface Conduction Electron-Emitter
(2008)
Li, Yiming
;
Kuo, Yi-Ting
;
Cheng, Hui-Wen
;
Yeh, Ta-Ching
;
Lo, Hsiang-Yu
In this work, the emission efficiency of the novel surface conduction electron-emitter corresponding to tilted angles (0) of the driving electrode is studied numerically. Due to the small angle, the emitter apex becomes significant and induces large electric field. The large electric field then attracts more particles into vacuum and then increases the emission current. However, the structure of the driving electrode limits the electron trajectory while the angle decreases, and it reflects the portion of collected current by the anode decreases and makes a drop in emission efficiency. It shows there is the highest emission efficiency (about 37%) under an optimum angle theta = 60 degrees. The result provides an insight into the relation between emission efficiency and emitter apex.
Emission Efficiency Dependence on the Width and Thickness of Nanogaps in Surface-Conduction Electron-Emitter Displays
(2009-05-01)
Li, Yiming
;
Lo, Hsiang-Yu
;
電信工程研究所
;
Institute of Communications Engineering
In this work, we explore the optimal size of nanogaps for the high field emission (FE) efficiency. In the FE process, the emission current is highly dependent upon both the material properties and the shape of the emitter. Thus, we first calibrate the theoretical model with the experimental data using the numerical simulation which is developed to evaluate the FE efficiency under different conditions. A three-dimensional finite-difference time-domain particle-in-cell method which approaches to self-consistent simulation of the electromagnetic fields and charged particles is adopted to simulate the electron emission in the surface-conduction electron-emitter display (SED) device. Examinations into conducting characteristics, FE efficiency, local electric fields around the emitter, and current density on the anode plate with one surface conduction electron-emitter (SCE) are conducted. It is found that the optimal width of nanogap in the SCE is about 80 similar to 90 nm and optimal thickness of the emitter is 30 nm to obtain the highest FE efficiency. This study benefits the advanced SED design for a new type of electron sources.
Field-emission properties of novel palladium nanogaps for surface conduction electron-emitters
(2007-11-28)
Lo, Hsiang-Yu
;
Li, Yiming
;
Chao, Hsueh-Yung
;
Tsai, Chih-Hao
;
Pan, Fu-Ming
We explore novel nanometer-scale gaps with different widths in palladium (Pd) thin-film strips using hydrogen absorption under high- ressure conditions and different temperatures. Both the experimental measurement and numerical calculation are conducted to examine the electron conduction properties of the newly proposed surface conduction electron- emitters (SCEs). It is shown that this novel structure exhibits a high emission efficiency, so that a low turn-on voltage of 40 V for an SCE with a 30 nm nanogap is obtained. A calibrated model is adopted to predict the effects of the emitter thickness and different material work functions on emission current with different width of nanogaps. It is found that the heightened thickness increases the emission current. However, it tends to saturate for smaller nanogaps. The decrement of work function is proportional to the increase in emission current, which is independent of the width of nanogap.
High field emission efficiency surface conduction electron emitters
(2008-09-01)
Li, Yiming
;
Chao, Hsueh-Yung
;
Lo, Hsiang-Yu
;
電信工程研究所
;
Institute of Communications Engineering
Two different surface conduction electron-emitter (SCE) structures with the nanogap of 90 nm wide fabricated by hydrogen embrittlement (HE) and focused ion beam techniques are simulated for the first time. We employ a three-dimensional particle-in-cell method coupling with finite-difference time-domain scheme to simulate the property of electron emission in these SCEs. Our calibrated simulation predicts high emission efficiency of the SCE structure which is fabricated by HE. Compared with the other SCE structure, it is observed that the proposed structure possesses low power consumption at the fixed emission current when the width of nanogap becomes narrower. The current-voltage characteristics including conducting mechanisms are investigated and explained.
Low Turn-On Voltage and High Focus Capability for Field Emission Display
(2008)
Kuo, Yi-Ting
;
Lo, Hsiang-Yu
;
Li, Yiming
;
電信工程研究所
;
Institute of Communications Engineering
In this work, the properties of low turn-on voltage and high focused capability for novel field emission display are studied. According to the development of novel structure for surface conduction electron-emitter provided by Tsai et al, the 3D FTDT-PIC method has been used to analyze the properties of this device. We can find the novel structure having a tip around the corner on the left electrode implies that it can produce high electric fields around the emitter apex, and generate high emission current.
Nanogap fabrication on palladium electrodes for field emission display applications
(2007)
Tsai, Chih-Hao
;
Chen, Kuan-Jung
;
Pan, Fu-Ming
;
Lo, Hsiang-Yu
;
Li, Yiming
We have used focused ion beam (FIB) to produce nanogaps on palladium thin film line electrodes. The two facing cross-sections of the as-prepared nanogap were smooth and exhibited a large turn-on voltage for electron field emission depending on the separation of the gap. Hydrogen plasma treatment was used to increase the edge roughness of the nanogap, and thereby dramatically improve the field emission characteristics. For a gap with a separation of 90 nm, the turn-on voltage reduced to 50 V from 175 V after the hydrogen plasma treatment.
Novel surface conduction electron emitter (SCE) nanogaps for field emission displays
(2008)
Tsai, Chih-Hao
;
Pan, Fu-Ming
;
Lo, Hsiang-Yu
;
Li, Yiming
;
Kuo, Yi-Ting
A novel nanometer scaled gap in palladium thin film strip was prepared by hydrogen absorption under high pressure conditions, and implemented in the fabrication of the surface conduction electron emitter (SCE) for flat panel display applications. The lattice constant increase in the Pd due to the phase transformation from the a-phase to the beta-phase after hydrogen absorption, a large compressive stress occurred to the Pd thin film. With a proper geometric arrangement of the Pd/Pt/Ti emitter electrode of the SCE structure, a single nanogap per SCE device was prepared. Finite element analysis was carried out to study the hydrostatic stress distribution in the thin film emitter structure after Pd hydrogenation, and thereby the optimized thickness of thin film electrodes of the emitter Was determined for the nanogap fabrication. The novel SCE emitter had an inclined protrusion structure on the cathode, which greatly enhance the local electrical field and improve electron beam focusing. The experimental measurement and theoretical analysis show that field emission properties of the novel SCE are superior to conventional SCE with the coplanar cathode.
Numerical simulation of field emission in the surface conduction electron-emitter display
(2007)
Lo, Hsiang-Yu
;
Li, Yiming
;
Chao, Hsueh-Yung
;
Tsai, Chih-Hao
;
Pan, Fu-Ming
We employ a three-dimensional (3D) particle-in-cell method coupling with finite-difference time domain scheme to simulate the electron emission in surface conduction electron-emitter displays (SEDs). This computational technique includes the space charge effects automatically. We thus explore the conducting mechanism, the emission efficiency, and the current density distribution on the anode plate with one field emission emitter.
Surface conduction electron emission in palladium hydrogenation nanogaps
(2008-04-21)
Li, Yiming
;
Lo, Hsiang-Yu
;
電信工程研究所
;
Institute of Communications Engineering
A nanometre scale gap (nanogap) structure in palladium strip fabricated by hydrogen absorption under high-pressure treatment was proposed and applied to the surface conduction electron emitter for flat panel displays. In this paper we demonstrate that the structure possesses different high field-emission efficiencies with low turn-on voltages and high focused capability, compared with the conventional type. An experimentally validated simulation is conducted to investigate the field-emission characteristics of the explored structure. It is observed the inclined sidewall and protrusion of this nanogap can enhance the local electric field and the focused capability and protect emission areas from being damaged by impurity ions during field-emission operation. This study benefits the advanced design of metallic electrodes in nanodevice technology for new types of electron sources and display applications.
Three-dimensional simulation of novel surface conduction electron-emitters
(2007)
Lo, Hsiang-Yu
;
Li, Yiming
;
Chao, Hsueh-Yung
;
Tsai, Chih-Hao
;
Pan, Fu-Ming
We for the first time explore a novel structure of Pd thin-film emitter fabricated on the substrate with various gaps ranging from mn to 90 nm. With the 3D electromagnetic particle-in-cell (PIC) simulation, we study the conducting mechanism and driving current for the new device with one palladium field emission emitter. Compared with the experimental data, our calibrated simulation predicts a high emission efficiency of the investigated device structure. It is found that the turn-on voltage is about 50V and a very high electron emission current of 0.1 mA is estimated at the anode voltage of 80 V for one emitter. The novel structure Of surface conduction electron-emitter (SCE) has the advantages of the simple fabrication and the high emission efficiency. Based upon the numerical procedure, we are currently investigating the emission efficiency for more advanced structures of SCE.