多通道势垒调控常关型金刚石FET原理及特性研究

The surface channel field-effect transistor, based on diamond materials, has great potential and prospects in the aspects such as ultrahigh power, ultrahigh frequency, high temperature, strong radiation etc., covering communication, transportation, aerospace, high-end defense equipment, and many other fields. However, the research on the normally-off devices has just started and the channel carrier concentration and mobility have to be sacrificed to obtain the normally-off type characteristic. In view of existing problems, this project proposes a multi-channel barrier-regulated normally-off diamond field-effect transistor, which aims to achieve normally-off type characteristics by depleting the two-dimensional hole gas in the channel with the effect of Schottky barrier ascribed from non-hydrogen and hydrogen termination. Moreover, the carrier concentration and mobility does not degrade. Exploring the variation law of the Schottky contact space charge zone with the height of the barrier and interface properties. Studying the influence of parameters such as space charge zone, channel width and etching depth on the distribution of electric field intensity in the multi channels, and explaining the mechanism that how to regulate the normally-off characteristic by the multi-channel structure. Clarifying the relationship between the electrical properties of the device and the surface characteristics, structural parameters, and establishing the corresponding device’s model. Successfully establishment of these theories and devices’ models will offer the basis for the design and optimization of FETs based on single crystal diamonds, and lay a solid foundation for further improvement of diamond power electronics.

以金刚石材料为基础的表面沟道场效应晶体管（FET）在超大功率、超高频、高温和强辐照等方面有巨大应用潜力和发展前景，涵盖了通讯、交通、航空航天、高端国防装备等诸多领域。然而目前针对常关型器件研究尚处于起步阶段，需要牺牲沟道载流子浓度和迁移率来获得常关型特性。本项目针对当前存在的问题，提出一种多通道势垒调控常关型表面沟道金刚石FET，旨在利用通道侧壁非氢终端与金属产生的肖特基势垒与栅极肖特基势垒共同耗尽通道内二维空穴气实现常关型特性，且载流子浓度与迁移率不受损伤。探索肖特基接触空间电荷区随势垒高度、界面特性的变化规律；研究空间电荷区、通道宽度和刻蚀深度等参数对通道内电场强度分布的影响，阐述多通道结构调控常关型特性的机理；明确器件电学性能与表面特性和结构参数的关系，建立对应器件模型。上述理论与器件模型的成功建立将为金刚石基FET的设计与优化提供依据，也为金刚石电力电子技术进一步发展奠定坚实基础。

以金刚石材料为基础的表面沟道场效应晶体管（FET）在超大功率、超高频、高温和强辐照等方面有巨大应用潜力和发展前景，涵盖了通讯、交通、航空航天、高端国防装备等诸多领域。然而目前针对常关型器件研究尚处于起步阶段，需要牺牲沟道载流子浓度和迁移率来获得常关型特性。. 本项目针对当前存在的问题，提出多种栅极结构调控常关型表面沟道金刚石FET，利用栅极与氢终端产生的空间电荷区耗尽通道内二维空穴气实现常关型特性，且载流子浓度与迁移率不受损伤。研究从多个思路出发，开展了金刚石氢终端与非氢端获得及其与不同金属形成肖特基结构特性、各类栅极结构沟道电场强度分布及电学性能、器件结构参数及特性等三方面的研究。最终，成功实现了常关型氢终端表面沟道单晶金刚石FET器件，探索了常关型器件电学特性与器件结构的内在关联，研究了栅极下方空间电荷区随器件结构参数及栅极材料的变化规律，阐述了器件结构调控常关型特性的机理。具体研究内容包括LaB6/氢终端金刚石场效应晶体管、Ti/TiOx栅极金刚石晶体管、Y栅极金刚石晶体管三种常关型器件结构及电学特性的研究，揭示了沟道关断的机理，解决了目前实现常关特性的技术手段对器件沟道载流子特性破坏、牺牲器件性能的问题，常关型器件最大源漏电流密度度、阈值电压等关键指标达到国际领先水平，为常关型的氢终端单晶金刚石FET的深入研发和应用提供了技术支持和理论指导。. 总体上讲上述既定目标已基本实现，各个主线研究内容也已完成。在项目的资助和支持下，以第一/通信作者在Carbon、IEEE Electron Device Letters、Applied Physics Letters、IEEE Transaction on Electron Devices、Diamond and Related Materials、ChemNanoMat等行业顶级、国际著名期刊发表SCI论文6篇，中科院1区论文1篇，2区论文3篇。合作发表SCI论文11篇，申请、获授权国家发明专利16项，圆满完成了预计指标。项目执行期间，共指导了4名硕士研究生，联合培养2名博士生。