垂直结构氮化镓功率晶体管的材料与工艺问题

硅功率器件已接近其理论物理性能的极限。基于宽禁带半导体材料的电力电子系统能够实现更高的功率密度和电能转换效率,而具有高临界电场和载流子迁移率的氮化镓被认为是未来高功率、高频和高温应用的最有希望的候选者之一,而由品质因子给出的氮化镓基功率器件的综合性能具有大于1 000倍于硅器件的理论极限。目前已产业化的氮化镓功率晶体管主要基于水平结构,但垂直结构更有利于实现更高电压和更大电流。随着氮化镓衬底材料的逐渐成熟,近期垂直结构氮化镓功率器件成为了学术界和产业界的研究热点,并被认为是下一代650～3 300 V电力电子应用的候选器件。基于此,回顾了垂直结构氮化镓晶体管的最新进展,特别是与器件相关的材料和工艺问题,并总结了开发高性能垂直结构氮化镓功率晶体管的主要挑战。

Materials and Processing Issues in Vertical GaN Power Transistors

Silicon-based power devices are reaching their fundamental performance limit. The use of wide-bandgap semiconductors offers potential for power electronic systems with much higher power densities and higher conversion efficiency. Gallium nitride(GaN), with a high critical electric field and carrier mobility, is considered as one of the most promising candidates for the future high-power, high-frequency and high-temperature applications. The comprehensive performance of GaN-based power devices given by the quality factor is 1 000 times of the theoretical limit of Si-based devices. At present, the industrialized GaN power transistors are primarily based on lateral structures, however, the vertical structures are more suitable for the realization of even higher voltage and larger current. Particularly, vertical GaN power devices have recently attracted increasing attention from academia and industrial cycles along with the gradual maturation of GaN substrate materials, and they are considered as candidates for applications of the nextgeneration 650~3 300 V power electronics. In this background, this paper reviews recent progress and the key remaining challenges towards the development of vertical GaN power transistors, with emphasis on the materials and processing issues related to each device architecture.