Investigations of GaN-based vertical field effect transistors for applications in high-power electronics

在这个项目中，常关电流孔径垂直场效应晶体管的概念（CAVET）将被调查的分析，外延，加工和表征的电子功率器件的基础上第III-N族半导体。本项目的目的是研究垂直晶体管，以提高关键器件参数的导通电阻和击穿电压在一个更高的水平比Si器件和横向GaN基器件。与以前的工作相比，这将使用外延方法来定义孔径。对于所需的厚缺陷贫GaN漂移层，氢化物气相外延（HVPE）生长将根据我们长期的经验，这种方法进行和分析。在这些先进的低缺陷密度衬底上，实际的器件结构将通过金属有机气相外延（MOVPE）生长，使用选择性区域外延用于所需的电流孔层，以最大限度地减少横向结构化期间的任何缺陷产生。在工艺方面，需要分析和执行垂直结构化和复杂的工艺流程，以探索垂直晶体管在电流和击穿稳定性方面的全部潜力。将研究与CAVET孔径相结合的新型常闭概念。IAF的完整器件模拟将指导和支持外延生长和器件加工。将特别关注所需的掺杂情况。将进行结构和电气表征，以了解这类新的高压操作设备的前景和局限性。工作计划由乌尔姆大学、弗赖堡大学和弗劳恩霍夫宇航联合会的小组共同定义和执行。这些团队的背景结合了该项目在半导体外延、加工、建模和表征方面所需的深入专业知识。

In this project, normally-off current aperture vertical field effect transistor concepts (CAVET) will be investigated for the analysis, epitaxy, processing, and characterization of electronic power devices based on group III-N semiconductors. The aim of this project is to investigate vertical transistors in order to enhance the key device parameters on-state resistance and breakdown voltage on a higher level than in Si devices and lateral GaN-based devices. In contrast to previous work this shall be accomplished using epitaxial approaches for the definition of the aperture. For the required thick defect-poor GaN drift layer, hydride vapor phase epitaxial (HVPE) growth will be performed and analyzed based on our long-standing experience of this method. On these advancedlow defect density substrates, the actual device structures will be grown by metalorganic vapor phase epitaxy (MOVPE) using selective area epitaxy for the required current aperture layers in order to minimize any defect generation during lateral structurization. On the processing side, vertical structuring and complex process flows need to be analyzed and performed in order to explore the full potential of the vertical transistor in terms of current flow and breakdown stability. Novel normally-off concepts in combination with the CAVET aperture shall be investigated. Full device simulations atIAF will guide and support epitaxial growth and device processing. Particular focus will be put on the required doping profiles. Structural and electrical characterization will be performed to understand the prospects and limitations of this new class of devices for high-voltage operation. The work program is defined and executed jointly by groups at the University of Ulm, University of Freiburg and Fraunhofer IAF. The background of the groups combines the required in-depth expertise for this project in terms of semiconductor epitaxy, processing, modeling and characterization.