3D Concepts for Gallium-Nitride Electronics

基于氮化镓（GaN）的电子器件如今通常用作高电子迁移率晶体管（HEMT），例如在移动的通信中。由于其3 MV/cm的高击穿电压和潜在的高工作温度，GaN也越来越多地被讨论用于中压范围内的未来电力电子器件。一般而言，GaN电子器件的进一步发展，特别是对于功率电子器件，通常被认为受到各种问题的阻碍，包括过高的缺陷密度、过低的瞬态功率耗散能力和有限的击穿行为。已被证明在电力电子领域极其有用的垂直器件几何形状（例如，在IGBT中）目前还不可用，这是由于缺少GaN高质量体衬底。如今的GaN FET技术依赖于平面HEMT方法，依赖于AlGaN-GaN界面处的2-dim电子气。我们项目的主要思想是探索基于3D GaN纳米棒的GaN电子产品的垂直概念。事实上，3D GaN纳米棒有可能克服平面2D HEMT技术的大部分上述限制，并可能在以后产生一种全新的GaN电子产品，当许多现有的基础问题得到解答时。该项目的概念是探索三维GaN（GaN纳米棒）作为新型垂直电子GaN基器件基础的潜力，特别强调-但不限于-电力电子。该项目是基于在TU布伦瑞克和Uni卡塞尔的两个参与小组在过去几年中关于GaN 3D微米和纳米棒的可再现MOVPE生长的实质性进展，在2英寸和4英寸衬底上大面积均匀制造纳米棒集合，以及对这种3D GaN纳米线特性的先进理论理解。总之，该项目旨在探索和开发未来垂直GaN MOSFET技术的核心工艺和器件策略。这种垂直设计概念将允许直接朝向大面积器件（通过使用例如与垂直电流路径并联的数百万个纳米FET）进行缩放，从而潜在地承载（和切换）非常大的电流。此外，平行的垂直3D器件几何形状将允许更有效的冷却策略。总体而言，我们的垂直器件战略解决了许多被确定为平面GaN功率器件中的严重挑战的问题。该项目的一个特别重要的方面将是3D GaN领域的实验和理论专业知识的结合。

Electronic devices based on Gallium Nitride (GaN) are nowadays regularly used as High Electron Mobility Transistors (HEMTs), e.g. in mobile communication. Due to its high breakdown voltage of 3 MV/cm and potentially high operating temperatures, GaN is also more and more intensely discussed for future power electronics in the intermediate voltage range. The further development of GaN electronics in general, and in particular for power electronics, is generally seen to be hampered by various issues, including too high defect densities, too low transient power dissipation capability and limited breakdown behavior. Vertical device geometries (e.g. in IGBTs), which have been proven to be extremely useful in power electronics, are not available, which is due to missing GaN high quality bulk substrates. GaN FET technology today is relying on a planar HEMT approach, relying on a 2-dim electron gas at the AlGaN-GaN interface. The main idea of our project is to explore a vertical concept for GaN electronics based on 3D GaN nanorods. In fact, 3D GaN nanorods would have the potential to overcome most of the above mentioned limitations of planar 2D HEMT technology and could lead to a completely new type of GaN electronics later on, when many of the existing foundational questions have been answered. The concept of this project is to explore the potential of 3-dimensional GaN (GaN nanorods) as a basis for novel vertical electronic GaN-based devices, with a particular emphasize - but not exclusively - on power electronics. The project is based on substantial progress in the two participating groups at TU Braunschweig and Uni Kassel over the last years concerning the reproducible MOVPE growth of GaN 3D micro- and nanorods, with large area homogenous fabrication of nanorod ensembles on 2 inch and 4 inch substrates, as well as an advanced theoretical understanding of the properties of such 3D GaN nanowires. In summary, the project aims at the exploration and development of central process and device strategies for a future vertical GaN MOSFET technology. Such vertical design concepts will allow straight forward scaling towards large area devices (by using e.g. millions of nanoFETs in parallel with vertical current path) potentially carrying (and switching) very large currents. Also, parallel vertical 3D device geometries would allow for more efficient cooling strategies. Overall, our vertical device strategy addresses many of the issues being identified as serious challenges in planar GaN power devices. A particularly important aspect of this project will be the combination of experimental and theoretical expertise in the field of 3D GaN.