Spatial correlation of electron field emission sites withnon-diamond carbon content in CVD diamond

Field-induced electron emission is obtained from 15 mm diameter CVD polycrystalline diamond films deposited on silicon wafers from a microwave discharge. These films were grown such that the percentage of non-diamond carbon is highest at the edge of the film. It was found that the majority of the emission sites also occured at the edge of the film     

Enhanced electron emission from phosphorus-doped diamond-cladsilicon field emitter arrays

Undoped and phosphorus (P)-doped diamond-clad Si field emitter arrays have been successfully fabricated using microwave plasma chemical vapor deposition (MPCVD) technology. The electron emission from the blunt diamond-clad microtips are much higher than those for the pure Si tips with sharp curvature due to a lower work function. Furthermore, the characteristics of emission current against applied voltage for the P-doped diamond-clad tips show superior emission at lower field to the undoped ones. After the examination of Auger electron spectroscopy (AES) and electrical characteristics of as-grown diamond, such a significant enhancement of the electron emission from the P-doped diamond-clad tips is attributed to a higher electron conductivity and defect densities     

Simulation and design of field emitter array

Some simulation results about potential, field strength, and emitting current density of cone-shaped emitter arrays are presented. Several important design features about the field emitter array are discussed. The most striking feature is that if one wants to obtain more current from the field emitter array in a given device area, there is a limit to the density of the emitter array due to the emitter tip field strength lowering effect, which is a result of the interaction from nearby surrounding tips. If one reduces the tip radius to increase the field strength a higher current density is compensated by a reduced effective emitting area; therefore, to obtain the highest emitter current for a certain set of designed emitter array geometric parameters a corresponding optimal tip radius needs to be determined     

Effect of diamond-like carbon coating on the emissioncharacteristics of molybdenum field emitter arrays

We have studied the electron emission characteristics of Mo field emitter arrays (FEAs) using a diamond-like carbon (DLC) film deposited by a layer-by-layer technique using plasma enhanced chemical vapor deposition. The turn-on voltage was lowered from 55 to 30 V by a 20 nm thick hydrogen-free DLC coating and maximum emission current was increased from 166 to 831 μA. Also the gate voltage required to get the anode current of 0.1 (μA/emitter) decreases from 77 to 48 V. Furthermore, the emission current from DLC coated Mo FEAs is more stable than that of noncoated Mo FEAs     

Optimization of electron beam focusing for gated carbon nanotube field emitter arrays

We fabricated gated field emitter arrays with a novel focusing structure of electron beams, where the focusing electrode concentrically surrounded each gate hole. Carbon nanotube emitters were screen printed inside an amorphous-Si concave well far below the gate. It was theoretically and experimentally verified that the concave well structure effectively focused the emitted electron beams to their designated phosphor pixels by modulating focusing gate voltages. For the vacuum packaged field emission displays with the pixel specification fitting high-definition televisions, color reproducibility of approximately 71% was achieved at the brightness of 400 cd/m/sup 2/.     

图案化定向碳纳米管阵列的场发射性能研究

考虑到碳纳米管的几何形貌会在一定程度上影响其场发射性能,如驱动电场,发射电流强度等,因此本文设计了三种不同的几何图案,并采用热气相化学沉积（TCVD）法制备出了相应几何结构的定向碳纳米管阵列;通过模拟计算和场发射测试实验,我们对以上三种结构的场发射性能进行比较,发现具有规则六边形蜂窝形状的碳纳米管阵列具有最强的边缘效应,最小的屏蔽效应,以及相同电场下最大的发射电流。     

微米金刚石薄膜的制备与场发射研究

利用微波等离子体化学气相沉积（MPCVD）法,在镀金属钛层的陶瓷基底上面,调整优化沉积参数,制备出了碳膜。通过各种仪器分析了碳膜的内部结构和表面形貌,证明该碳膜是微米金刚石薄膜。进一步将微米金刚石薄膜作为场发射阴极材料,测试了其场致电子发射特性。稳定发射状态下的开启电场为1.15V/μm, 在3.35V/μm的电场下,其场发射电流密度为0.81mA/cm2,发射点密度约为104/ cm2。并对其发射机理进行了研究。     

Uniform electron emission from a nitrogen-doped diamond-basedelectron emitter fabricated by the sintering technique

A nitrogen (N)-doped diamond-based electron emitter has been fabricated by the sintering technique prior to the chemical vapor deposition process in order to improve the uniformity. There are no spatial differences in reflective electron energy loss spectra (REELS) from the diamond-based electron emitter, suggesting that uniform surface conditions are obtained. The uniform electron emission from the obtained electron emitter is confirmed through emission current vs anode voltage characteristics measurements. It seems that the uniformity of the emitter surface results in uniform electron emission from the diamond electron emitter     

Rate equation of current degradation of the Spindt-type field emitter array

The degradation rate of the emission current of the Spindt-type field emitter arrays in the display environment has been measured. The relative degradation rate is found to be a function of the square of emission current and proportional to the anode bias (voltage). A life model is presented that leads to development of an analytical rate equation of emission current degradation. Based on this model, there is a steady-state level at which the emission current is stable. The steady-state emission current depends on anode bias, background pressure in the package and cleanliness of anode and cathode surfaces. Experimental results are consistent with the rate equation derived from the model. Since the model does not include any material and process that make the cathode, it could probably apply to any field emission cathodes.     

Improvement of electron emission efficiency and stability bysurface application of molybdenum silicide onto gated poly-Si fieldemitters

As an approach to improve electron field emission and its stability, molybdenum (Mo) silicide formation on n⁺ polycrystalline silicon (poly-Si) emitters has been investigated. Mo silicide was produced by direct metallurgical reaction, namely, deposition of Mo and subsequent rapid thermal annealing. The surface morphologies and emission properties of Mo-silicided poly-Si (Mo-polycide) emitters have been examined and compared with those of poly-Si emitters. While anode current of 0.1 μA per tip could be obtained at the gate voltage of 82 V from poly-Si emitters, the same current level was measured at 72 V from Mo-polycide emitters. In addition, the application of Mo silicide onto poly-Si emitters reduced the emission current fluctuation considerably. These results show that the polycide emitters can have potential applications in vacuum microelectronics to obtain superior electron emission efficiency and stability     

利用场发射扫描电镜的低电压高性能进行材料表征

场发射扫描电子显微镜（FESEM）是一种高分辨扫描电镜,在材料分析中得到广泛应用。尤其是良好的低压高空间分辨性能和低压下良好的SE像相互结合使用,使SEM应用范围得到扩展。     

球状微米金刚石的制备过程及其场发射性能的研究

在纯平的陶瓷衬底上面,利用磁控溅射方法镀上一层金属钛。对金属钛层进行表面缺陷处理后,放入微波等离子体化学气相沉积腔中,利用正交实验方法制备出场发射性能最优的薄膜,通过扫描电镜、X射线衍射仪、拉曼光谱仪等仪器,研究了薄膜的微观表面形态、结构组成等,得到了该薄膜是球状微米金刚石薄膜的结论。并进一步研究了最优场发射薄膜的发射机理。     

外场下等离子体中波的增强和带电粒子流的加速

在不考虑碰撞机制的情况下,研究了外加高频电磁场(泵波)下等离子体中Langmuir波和离子声波的增强以及带电粒子流的加速.基于流体力学方程,推导了描述等离子体参量不稳定性的振动方程,进一步得到描述带电粒子流加速的数学表达式和有质动力的数学表达式.结果表明,在等离子体参量不稳定性的激发过程中,Langmuir波和离子声波得以增强以及带电粒子流由于泵波与Langmuir波(离子声波)的耦合而加速;有质动力的产生是由于泵波与Langmuir波(离子声波)的耦合而且它是参量不稳定过程的策动力,另外有质动力不仅存在高频分量,还存在低频分量.     

激光在硅基底沉积类金刚石膜的光学应用

研究了氧气氛和掺硅对类金刚石(DLC)膜性能的影响机理.采用飞秒激光烧蚀石墨靶材,通过氧气氛、掺硅和离轴平移旋转等技术,在硅基底上镀制出比传统工艺透过率、硬度、附着力和稳定性等性能更优的无氢DLC膜.实验验证了随着氧气氛压强的增大,样片透过率先增大后减小,存在一个最佳气压(2 Pa).并且掺硅有助于改善DLC膜的性能,掺硅量也存在一个最佳值.在3-5 μm波段,正面镀DLC膜、背面镀普通增透膜的硅红外窗口的平均透过率≥91.7%,DLC膜的纳米硬度高达40～50 GPa.且通过军标规定的高温、低温、湿热、盐雾、重摩擦等环境实验.满足光学窗口工程应用的要求.     

热敷法制备丝状阴极及其在场发射中的应用

采用热敷法将碳纳米管(CNT)浆料直接热敷在Ni丝上制备成丝状阴极,并在圆柱形灯管中采用二极结构测试其场发射性能.扫描电镜(SEM)测试表明,丝状阴极的表面有一层均匀的CNT材料;场发射结果表明,CNT-Ni丝状阴极与传统的场发射阴极相比具有更优良的场发射性能,开启电场为0.15 V/μm,当电压为2280V时发射电流达到4 mA.在腔体中测试其发光亮度,最高值达到了14000 cd/m2.     

Study on the vacuum breakdown in field emission of a nest array of multi-walled carbon nanotube/silicon nanoporous pillar array

A composite structure, a nest array of multi-walled carbon nanotubes/silicon nanoporous pillar array (NACNT/Si-NPA), with good field emission properties, was synthesized through growing CNT on Si-NPA by thermal chemical vapor deposition. In order to make full use of its good field emission properties, the vacuum breakdown behavior accompanied with field emission from NACNT/Si-NPA was investigated. The results revealed that a positive feedback of field emission and resulted Joule heat ignited a small portion of protruding emitters, which caused spark discharge, destroyed the anode and generated a large amount of heat. The thermal runaway ultimately resulted in the destruction of substrate and vacuum breakdown.     

Design and research of quasi-planar self-aligned silicon avalanche electron emission array

The device structure and technical processings of quasi-planar self-aligned silicon avalanche electron emission array arc introduced. The processing step at the edge of electron emission region is about 10nm only and the width of self-aligned current channel of shallow As implantation is about 3μm. Its I-V characteristics show a larger linear region and lower series resistance than that of the previous silicon avalanche electron emission devices. Some of the electron emission characteristics are also discussed in this paper.     

Investigation of growth properties of patterned and aligned carbon nanotubes for field emitter

We demonstrate the use of microstructures as an inducement for the growth of patterned and aligned carbon nanotubes (CNTs) during thermal chemical vapor deposition process. The growth of individual nanotube lines of vertical-standing 8-10 μm length can be controlled in almost any directions. In directions of approximate 90°, 60°, 45° or 0° relative to substrate surface, kinds of aligned CNTs patterns were synthesized. We also show that the flow of carrier gas and apical dominance like plant growth are the main factors of patterning CNTs, which indicates that the distribution of electric field can be controlled and the shielding effects can be weakened. The result establishes a method of patterned and aligned nanotubes, which is well suited for ordered arrays of CNTs field emitters. The field emission currents were observed to be fairly reproducible ranging from 375 to 1000 V and field emission measurements show a low turn-on field (1.25 V/μm).     

衬底对微米金刚石聚晶薄膜生长及场发射特性的影响

摘要：本文在陶瓷衬底上面利用磁控溅射的方法镀上一层厚金属钛,用不同方法对金属钛层进行表面处理,处理后的衬底放在微波等离子体化学气相沉积腔中,在相同的沉积条件下制备出不同微米金刚石薄膜。对不同的薄膜的微观表面形态、结构组成进行对比研究;对不同的薄膜用二极管型结构测试了它们的场致发射电子的性能,并对发射机理进行了深入的研究。最终分析出不同方法处理的衬底,对微米金刚石聚晶薄膜生长及场发射特性的影响的原因。