Microplasmas from Diamond Arrays

来自金刚石阵列的微等离子体

• 批准号: EP/G069980/1
• 负责人: Paul May
• 金额: $ 44.35万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG069980%2F1
• 关键词: Microplasmas; Diamond; Arrays

Microplasmas are smaller scale versions of the hollow cathode discharges which have been widely used for almost 100 years as high electron density, low pressure discharge devices for a variety of applications. Hollow cathode discharges comprise two electrodes - an anode, and a cathode shaped like a hollow tube or cavity - separated by a small gap. When a high voltage is applied across these electrodes, a plasma is formed in the gap which extends inside the cavity. Normally such hollow cathode devices work at very low pressures, but as the dimensions of the electrodes and the cavity decrease to below a few 10s of um, the pressure at which the plasma can be maintained rises to ~1 atmosphere. Often referred to as 'microdischarges' or 'microplasmas', these atmospheric pressure discharges represent a new and fascinating realm of plasma science. Many thousands of microcavities can be fabricated as arrays onto a substrate, allowing large area flat panels plasma devices to be made. The number of applications for these devices is growing rapidly. Microplasmas have begun to find uses such as the destruction of volatile organic compounds (VOCs) which can be contaminants in air supplies or present in waste gases from industrial processes. This makes such devices candidates for advanced life support systems, such as in submarine, aircraft, and spacecraft, and for exhaust gas clean up from, say, the electronics industry. One application is the potential use of large arrays of microcavity plasma devices as flat panel displays for computers or TVs. Microplasmas can also be used as excimer light sources, particularly in the deep-UV, suggesting the possibility of large area flat panel monochromatic light sources. Microplasmas can also be used as micro-sized chemical-reactors. To date, the range of electrode materials employed in microplasma devices ranges from refractive metals to semiconductors, and different, but compatible materials are required for different parts of the device. For the electrodes, metals such as Mo, Ni, Pt, Ag and Cu have been used, whereas alumina and boron nitride are needed for other parts of the device.The aim of the proposed work is to fabricate microplasma arrays using diamond in the active components. The superlative properties of diamond, such as its chemical inertness, low wear rate, low sputter rate, negative electron affinity, high secondary electron yield, and compatibility with Si technology, give it a number of major advantages over conventional materials used for these devices. In particular, the fact that the electrical conductivity of diamond can be controllably varied from highly insulating through to metallic, simply by changing the concentration of the dopant, will allow essentially all the components of the microplasma array to be fabricated from this one material. The electrodes would be made from highly B-doped diamond (deposited in Bristol by chemical vapour deposition techniques), giving high conductivity with high electron emission efficiency. The insulating dielectric would be made from the oxidised undoped diamond surface. The entire device could be made on a Si wafer for compatibility with existing Si microfabrication techniques, or from a thick undoped CVD diamond substrate, thus giving all the benefits of high thermal conductivity and therefore the potential for device operation at high power levels. The alternative strategy is to use inkjet coating technology that developed at Bristol to direct-write thick layers of doped/undoped/doped nanodiamond powder sandwich structures onto a suitable substrate.The project is a collaboration between Bristol University, who will deposit the CVD/inkjet diamond layers, the Rutherford-Appleton lab, who will develop etching processes to pattern the diamond into microcavities, and the Open university, who will test the devices and arrays for performance and lifetime.

微等离子体是空心阴极放电的较小尺度版本，其作为高电子密度、低压放电装置已被广泛用于各种应用近100年。空心阴极放电包括两个电极-阳极和形状像空心管或空腔的阴极-由小间隙分开。当在这些电极上施加高电压时，在空腔内部延伸的差距中形成等离子体。通常，这种空心阴极装置在非常低的压力下工作，但是当电极和腔的尺寸减小到低于几十μ m时，等离子体可以保持的压力上升到约1个大气压。通常被称为“微放电”或“微等离子体”，这些大气压放电代表了等离子体科学的一个新的和迷人的领域。可以将数千个微腔作为阵列制造到衬底上，从而允许制造大面积平板等离子体装置。这些设备的应用数量正在迅速增长。微等离子体已经开始找到用途，例如破坏挥发性有机化合物（VOC），这些化合物可能是空气供应中的污染物或工业过程废气中的污染物。这使得这些设备成为先进生命支持系统的候选人，例如潜艇，飞机和航天器，以及电子工业的废气清理。一个应用是微腔等离子体装置的大阵列作为计算机或电视的平板显示器的潜在用途。微等离子体也可以用作准分子光源，特别是在深紫外线中，这表明大面积平板单色光源的可能性。微等离子体也可以用作微型化学反应器。迄今为止，微等离子体装置中采用的电极材料的范围从折射金属到半导体，并且装置的不同部分需要不同但相容的材料。对于电极，金属，如钼，镍，铂，银和铜已被使用，而氧化铝和氮化硼的其他部分的装置所需要的。金刚石的最高性能，如其化学惰性，低磨损率，低溅射率，负电子亲和力，高二次电子产率，以及与Si技术的兼容性，使其具有许多优于用于这些设备的传统材料的主要优点。特别地，简单地通过改变掺杂剂的浓度，金刚石的电导率可以可控地从高绝缘性变化到金属性，这一事实将允许微等离子体阵列的基本上所有部件都由这一种材料制造。电极将由高硼掺杂金刚石（通过化学气相沉积技术沉积在布里斯托）制成，具有高导电性和高电子发射效率。绝缘电介质将由氧化的未掺杂金刚石表面制成。整个器件可以在Si晶片上制造，以与现有的Si微制造技术兼容，或者由厚的未掺杂CVD金刚石衬底制成，从而提供高热导率的所有好处，因此具有在高功率水平下操作器件的潜力。另一种策略是使用布里斯托开发的喷墨涂层技术，将掺杂/未掺杂/掺杂纳米金刚石粉末夹层结构的厚层直接写入到合适的基底上。该项目是布里斯托大学（将存款CVD/喷墨金刚石层）、卢瑟福-阿普尔顿实验室（将开发蚀刻工艺以将金刚石图案化为微腔）和开放大学之间的合作，他们将测试设备和阵列的性能和使用寿命。

项目成果

High-pressure dc glow discharges in hollow diamond cathodes

空心金刚石阴极中的高压直流辉光放电

• DOI: 10.1088/0963-0252/25/2/025005
• 发表时间: 2016
• 期刊: Plasma Sources Science and Technology
• 影响因子: 3.8
• 作者: Truscott B

Electrospray Deposition of Diamond Nanoparticle Nucleation Layers for Subsequent CVD Diamond Growth

• DOI: 10.1557/proc-1203-j17-27
• 发表时间: 2009
• 期刊: MRS Proceedings
• 作者: O. Fox;J. Holloway;G. Fuge;P. May;M. Ashfold

Generation of microdischarges in diamond substrates

金刚石基底中微放电的产生

• DOI: 10.1088/0963-0252/21/2/022001
• 发表时间: 2012
• 期刊: Plasma Sources Science and Technology
• 影响因子: 3.8
• 作者: Mitea S