Pantle Florian, Becker Fabian, Kraut Max, Wörle Simon, Hoffmann Theresa, Artmeier Sabrina, Stutzmann Martin
Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
Nanoscale Adv. 2021 May 5;3(13):3835-3845. doi: 10.1039/d1na00221j. eCollection 2021 Jun 30.
GaN-on-diamond is a promising route towards reliable high-power transistor devices with outstanding performances due to better heat management, replacing common GaN-on-SiC technologies. Nevertheless, the implementation of GaN-on-diamond remains challenging. In this work, the selective area growth of GaN nanostructures on cost-efficient, large-scale available heteroepitaxial diamond (001) substrates by means of plasma-assisted molecular beam epitaxy is investigated. Additionally, we discuss the influence of an AlN buffer on the morphology of the GaN nanostructures. The nanowires and nanofins are characterized by a very high selectivity and controllable dimensions. Low temperature photoluminescence measurements are used to evaluate their structural quality. The growth of two GaN crystal domains, which are in-plane rotated against each other by 30°, is observed. The favoring of a certain domain is determined by the off-cut direction of the diamond substrates. By X-ray diffraction we show that the GaN nanostructures grow perpendicular to the diamond surface on off-cut diamond (001) substrates, which is in contrast to the growth on diamond (111), where the nanostructures are aligned with the substrate lattice. Polarity-selective wet chemical etching and Kelvin probe force microscopy reveal that the GaN nanostructures grow solely in the Ga-polar direction. This is a major advantage compared to the growth on diamond (111) and enables the application of GaN nanostructures on cost-efficient diamond for high-power/high-frequency applications.
由于具有更好的热管理性能，基于金刚石的氮化镓（GaN-on-diamond）是一种有望实现可靠的高性能大功率晶体管器件的途径，有望取代常见的基于碳化硅的氮化镓（GaN-on-SiC）技术。然而，基于金刚石的氮化镓的实现仍然具有挑战性。在这项工作中，研究了通过等离子体辅助分子束外延在具有成本效益的大规模可用异质外延金刚石（001）衬底上选择性区域生长氮化镓纳米结构。此外，我们讨论了氮化铝（AlN）缓冲层对氮化镓纳米结构形貌的影响。纳米线和纳米鳍具有非常高的选择性和可控尺寸。低温光致发光测量用于评估它们的结构质量。观察到两个氮化镓晶畴的生长，它们在平面内彼此相对旋转30°。特定晶畴的择优取向由金刚石衬底的切角方向决定。通过X射线衍射我们表明，氮化镓纳米结构在切角金刚石（001）衬底上垂直于金刚石表面生长，这与在金刚石（111）上的生长情况相反，在金刚石（111）上纳米结构与衬底晶格对齐。极性选择性湿化学蚀刻和开尔文探针力显微镜表明，氮化镓纳米结构仅沿Ga极性方向生长。与在金刚石（111）上的生长相比，这是一个主要优势，并且使得氮化镓纳米结构能够应用于具有成本效益的金刚石上，用于高功率/高频应用。
