Collaborative Research EAGER: Reliable High Current Density Vacuum Electronics

基于通过真空控制电子运动的真空电子器件和系统具有许多应用，包括等离子体显示器、用于通信和成像的微波和太赫兹辐射源、扫描电子显微镜以及用于极端环境的电子器件。然而，有效且可靠地将电子发射到真空中的装置由于其低电流密度和差的可靠性而具有挑战性。该项目由普渡大学和俄亥俄州州立大学合作，旨在展示真空发射器的新设计，使其能够在高电流密度下可靠地运行。涉及两种不同半导体的两种互补方法-硅和氮化镓将用于演示真空发射器，由详细的电子和热建模技术指导。所提出的工作将能够实现高性能的真空电子器件，可以集成在半导体芯片上的微米尺度。这些微型高电流密度发射器将超越当前的最新技术水平，并可以实现大量的新应用，这些应用利用真空电子技术进行显示、高数据速率通信、高温电子技术和成像。该项目将导致在半导体技术的高度跨学科和新领域的研究生的培训和教育，并可能导致真空电子电路和系统的几个新的商业相关应用。这个合作项目将联合收割机结合在硅制造和真空电子学在普渡大学，和III族氮化物异质结构和极化工程在俄亥俄州州立大学，以证明可靠的高电流密度发射器。本文将研究一种新的硅场致发射体的方法，利用硅中具有相当低的载流子浓度的电流饱和效应，将硅发射体设计成通过晶格和电离杂质散射限制输运来控制电流密度。一个平行的方法，使用异质结构和极化工程将追求实现高效的场发射平面III族氮化物半导体结构。III族氮化物半导体具有固有的极化，使得大电压能够在纳米级距离上下降。这使得现场工程能够将半导体内的导带与外部的真空水平对准。极化工程的概念将与超尺度结构中的弹道传输相结合，以实现III族氮化物半导体表面的有效场发射。所提出的器件将使高电流密度场发射在平面几何形状，这可能是有利的几个应用。复杂的建模技术，包括二维电热模拟和蒙特卡罗模拟异质结构中的传输将在普渡大学和俄亥俄州州立大学开发，以设计和评估硅和III族氮化物材料系统中的真空发射器。将进行集成真空电子器件的微制造技术的开发和演示。拟议的工作将使人们更好地了解工程纳米级结构和III族氮化物半导体的场发射。这里提出的概念使用有前途的新方法来克服与高电流密度发射器相关的挑战，因此可能对真空微电子学的科学和应用产生变革性的影响。

Vacuum electronic devices and systems, which are based on the control of electron motion through vacuum, have numerous applications including plasma displays, microwave and terahertz radiation sources for communications and imaging, scanning electron microscopes, and electronics for extreme environments. However, devices that efficiently and reliably emit electrons into vacuum have been challenging due to their low current density and poor reliability. The proposed project, a collaboration between Purdue University and Ohio State University, aims to demonstrate new designs for vacuum emitters to enable them to operate reliably at high current densities. Two complementary approaches involving two different semiconductors - Silicon and Gallium Nitride will be used to demonstrate vacuum emitters, guided by detailed electronic and thermal modeling techniques. The proposed work will enable realization of high-performance vacuum electronic devices that can be integrated on semiconductor chips at the micrometer scale. These microscale high current density emitters would surpass the current state-of-art and could enable a large array of new applications that exploit vacuum electronics for display, high data-rate communications, high-temperature electronics, and imaging. The project will lead to training and education of graduate students in a highly interdisciplinary and novel area of semiconductor technology, and could lead to several new commercially relevant applications for vacuum electronic circuits and systems.This collaborative project will combine the complementary expertise in Si fabrication and vacuum electronics at Purdue University, and III-nitride heterostructure and polarization engineering at Ohio State University to demonstrate reliable high current density emitters. A new approach to Si field emitters will be investigated to take advantage of current saturation effects in Silicon with fairly low carrier concentration, The Si emitters will be designed to control current density through lattice and ionized impurity scattering limited transport. A parallel approach using heterostructure and polarization engineering will be pursued to achieve highly efficient field emission in planar III-nitride semiconductor structures. III-nitride semiconductors have intrinsic polarization that enables large voltages to be dropped across nanometer scale distances. This enables field engineering to align the conduction band within the semiconductor with the vacuum level outside. The polarization engineering concepts will be combined with ballistic transport in ultrascaled structures to achieve efficient field emission from III-nitride semiconductor surfaces. The proposed device will enable high current density field emission in planar geometries that could be advantageous for several applications. Sophisticated modeling techniques including 2-dimensional electro-thermal simulations and Monte Carlo simulations of transport in heterostructures will be developed at Purdue University and Ohio State University to design and evaluate the vacuum emitters in both Silicon and III-nitride material systems. Development and demonstration of micro-fabrication technology for integrated vacuum electronic devices will be done. The proposed work would lead to better understanding of field emission from engineered nanoscale structures and III-nitride semiconductors. The concepts proposed here use promising and novel approaches for overcoming challenges related to high current density emitters, and could therefore have transformative impact on the science and applications of vacuum microelectronics.