采用转移掺杂介质的氢终端金刚石场效应管制备、特性和稳定性研究

Surface conductivity of the hydrogen-terminated diamond (H-diamond) can be formed by the transfer-doping of atmospheric adsorbates at room temperature, and the field effect transistors (FETs) fabricated based on this surface conductivity are the mainstream device structure of the current diamond electronic devices. Some materials with high electron affinity (HEA), e.g. MoO3, have also demonstrated transfer-doping effect on H-diamond, and efficiently raised the surface conductivity. Meanwhile, these materials as dielectrics can improve the thermal stability and over-time stability, and help to solve the long-standing problems related to the small and unstable conductivity of H-diamond caused by the nature of atmospheric adsorbates. Therefore, utilizing these HEA materials in diamond FETs as both the surface doping material and the dielectric could pave new ways to realize high performance diamond FETs with high stability. This project will explore the modulation, control and optimization of the transfer-doping effect of these HEA materials on H-diamond, and reveal the relationship between the traps, leakage and thermal stability of them and the transfer-doping effect and explore the relevant physical mechanisms. We will further research the device performance, thermal and over-time stability and radiation resistance of the diamond FETs utilizing these dielectrics, and then find out the optimization methods of the dielectric characteristics and the device structure. We expect to realize the diamond FETs with the maximum output current over 300mA/mm, or the off-state source-drain breakdown voltage over 200V, and the reduction of the output current at 200℃ compared with that at room temperature should be less than 20%.

氢终端金刚石可由空气吸附物转移掺杂在室温下形成表面电导，基于该电导制备的场效应管（FET）是目前金刚石电子器件的主流结构。MoO3等高电子亲和能材料对氢终端金刚石也有转移掺杂作用，可有效提高其表面电导；同时这类材料作为介质，可提高表面电导的热稳定性和随时间的稳定性，有望解决传统的空气吸附氢终端电导偏小且稳定性较差的问题。因此，采用MoO3等材料兼做表面掺杂和介质，为研制高性能高稳定性金刚石FET提供了新的途径。本项目将探索MoO3等介质对氢终端金刚石转移掺杂作用的调控和优化方法，揭示介质的陷阱、漏电、热稳定性等和其掺杂作用的相关性和物理机制，研究采用这类介质的氢终端金刚石FET的器件性能和热稳定性、随时间稳定性和抗辐照特性的表现，提出介质特性和器件结构的优化方法。最终将实现金刚石FET特性：最大输出电流≥300mA/mm；关态源漏击穿电压≥200V；200℃输出电流比室温下降量≤20%。

金刚石是一种典型的超宽禁带半导体材料，具有击穿场强高、载流子输运特性好、热导率极高等优异的性质，适合高速大功率电子器件应用。金刚石的高效体掺杂尚未解决，氢终端金刚石在室温下具有表面p型电导，氢终端金刚石场效应管是目前金刚石有源电子器件的主流结构。然而，氢终端金刚石的表面电导是由空气吸附物转移掺杂形成的二维空穴气提供，有迁移率低、稳定性差的缺点。.本项目开展了氢终端金刚石上固态转移掺杂介质MoO3、Al2O3和HfO2等的转移掺杂作用和采用这些介质的氢终端金刚石场效应管的制备、特性和稳定性研究。研究揭示了氢终端金刚石表面MoO3介质的转移掺杂作用，建立MoO3/Si3N4双层介质的优化结构和制备方法，研制出具有高输出电流、高跨导和低导通电阻的场效应管。扩展了固态转移掺杂理论，揭示了氢终端金刚石上300℃-ALD Al2O3或HfO2介质转移掺杂的机理，研制出的Al2O3/氢终端金刚石器件具有出色的大信号动态开关特性和重复测量稳定性，实现最大漏极输出电流密度415mA/mm，源漏关态击穿电压>200V，200℃器件输出电流比室温下降量19.4%。还开展了一些相关研究，制备出氢终端金刚石/氟化物介质高电导增强型MISFET器件，揭示了高电导增强型沟道形成机理；揭示了面向高频小信号应用的氢终端金刚石场效应管横向等比例缩小规律，以及面向微波功率应用的氢终端金刚石场效应管的直流和微波特性的内在关系和器件性能的关键制约因素。.本项目共发表SCI论文12篇，出版1部专著《金刚石半导体器件前沿技术》（张金风，张景文，蔚翠，刘金龙 著，西安电子科技大学出版社，2022）；申请国家发明专利4项均授权，其中2项实现技术转让，转让金75万元。培养博士研究生1人、硕士研究生7人。