CAREER: A New GaN-based Unit Cell for Highly Efficient Integrated Power Conversion

这项教师早期职业发展（Career）计划的研究目标是开发一种具有集成驱动电路的极低损耗功率晶体管，用于功率转换应用。该方法将使用一种创新的制造工艺来解决基于氮化镓的垂直晶体管的问题，这些问题以前限制了该技术实现卓越性能和广泛采用。由于能量转换效率低下，大量的能量以热能的形式被浪费了。通过该方案提供的解决方案将减少或消除浪费的能源，从而有效地延长可用能源的使用寿命。这种能源节约将增加全球能源安全并减少温室气体排放。教育和推广部分旨在培养对科学、技术、工程和数学（STEM）学科的兴趣，并在本科和K-12阶段发展科学知识。这些活动的重点是与不同的学生群体合作，特别是妇女和其他代表性不足的群体。研究和教育的整合将通过专门了解半导体器件的研讨会和课程来实现，并为他们的K-12教室建立原型或模型。具体的拓展目标包括通过工程冒险与K-8女孩合作，通过工程师服务教育与师范学院候选人合作。教育目标是继续建立在最近介绍的电力电子课程，并扩展通过该计划下的研究获得的前沿技术知识。氮化镓氮极取向的独特极化特性将首次被用于开发垂直晶体管，在结构生长过程中不需要中断。氮化镓铝/氮化镓异质结构的反极化场被设计为阻断晶体管中的电流，同时为电流在指定区域流动提供非常导电的路径。导通状态电阻低于1mohm。从这种新型晶体管设计中估计出Cm2，并将其作为本程序的目标。由于电路板互连和键合线电感的有害影响，缺乏集成栅极驱动器限制了功率变换器的高开关速度和效率。这项创新将电力电子技术的极限推向了非常高的功率密度，并在高频率下提供高效率，首先开发了性能优越的氮基垂直晶体管，然后通过集成基于片上横向晶体管的驱动电路，消除了键合线和板互连的痕迹电感对开关速度的限制。这项研究的范围扩展到基础器件研究和应用空间，其中器件结构将用于确定材料的基本性质，包括氮化镓中电子速度的第一次直接测量。最后，通过在高频下实现高效率的功率转换，从而提高效率和减小外形因素的新电路架构将证明其优点。

The research objective of this Faculty Early Career Development (CAREER) Program award is to develop a very low loss power transistor with an integrated drive circuit for power conversion applications. The approach will use an innovative fabrication process to address issues with Gallium Nitride-based vertical transistors that have previously limited the technology from achieving superior performance and widespread adoption. A significant amount of energy is wasted as heat due to inefficient power conversion. The solution provided through this program will reduce or eliminate the wasted energy thereby effectively extending the lifetime of available energy resources. This energy savings will add to the global energy security and reduce greenhouse gas emissions. The educational and outreach components are aimed at fostering interest in Science, Technology, Engineering, and Mathematics (STEM) disciplines and developing scientific knowledge at the undergraduate and K-12 levels. These activities are focused on working with a diverse group of students particularly women and other underrepresented groups. Integration of the research and education will be achieved through workshops and classes dedicated to understanding semiconductor devices and build prototypes or models for their K-12 classrooms. Specific outreach goals include collaboration with K-8 girls through Engineering Adventure and Teacher College candidates through Engineers Serving Education. The educational goal is to continue building on a recently introduced coursework on power electronics and extend the knowledge on cutting edge technologies acquired through the research under this program.The unique polarization properties of the nitrogen polar orientation of Gallium nitride will be utilized for the first time to develop vertical transistors that require no interruptions during the growth of the structure. The reverse polarization field of the Aluminum Gallium Nitride/Gallium Nitride heterostructure is designed to block current in the transistor while providing a very conductive path for the current to flow in designated region. An on-state resistance below 1 mohm.cm2 is estimated from this novel transistor design and is set as a target in this program. Lack of an integrated gate driver has limited high switching speed and efficiency of power converters due to the deleterious effects of board interconnects and bond wire inductance. This innovation pushes the limits of power electronics to very high power densities with high efficiency delivered at high frequencies by first developing superior performance of nitride-based vertical transistors and then eliminating the limits placed on switching speed by trace inductance of bond wires and board interconnects by integrating the driver circuit based on lateral transistors on-chip. The scope of this research extends into both fundamental device research and application space where the device structures will be used to determine fundamental properties of the material including the first direct measurement of electron velocity in Gallium nitride. Finally the merit will be evident through new circuit architectures with increased efficiency and reduced form factor by enabling high efficiency power conversion at high frequencies.