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

这个教师早期职业发展（CAREER）计划奖的研究目标是开发一个非常低损耗的功率晶体管与功率转换应用的集成驱动电路。该方法将使用创新的制造工艺来解决氮化镓基垂直晶体管的问题，这些问题以前限制了该技术实现上级性能和广泛采用。由于功率转换效率低，大量能量被浪费为热量。通过该计划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。 这种节能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水平上发展科学知识。这些活动的重点是与不同的学生群体，特别是妇女和其他代表性不足的群体合作。研究和教育的整合将通过致力于理解半导体器件的研讨会和课程来实现，并为他们的K-12教室构建原型或模型。具体的推广目标包括通过工程探险与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。该项目的教育目标是在最近推出的电力电子课程的基础上，继续扩展通过该项目的研究获得的尖端技术知识。氮化镓的氮极性取向的独特极化特性将首次用于开发在结构生长期间不需要中断的垂直晶体管。氮化铝镓/氮化镓异质结构的反向极化场被设计为阻挡晶体管中的电流，同时为电流在指定区域中流动提供非常导电的路径。低于1 mohm.cm 2的通态电阻估计从这种新颖的晶体管设计，并设置为在这个程序中的目标。由于板互连和接合线电感的有害影响，集成栅极驱动器的缺乏限制了功率转换器的高开关速度和效率。这一创新将功率电子器件的极限推到非常高的功率密度，并在高频下提供高效率，其方法是首先开发基于氮化物的垂直晶体管的上级性能，然后通过集成基于片上横向晶体管的驱动器电路来消除键合线和板互连的迹线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特性，包括氮化镓中电子速度的首次直接测量。最后，通过实现高频下的高效率功率转换而具有增加的效率和减小的形状因子的新电路架构，优点将是明显的。

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.