Conduction Mechanisms in Al0.84In0.16N/AlN/GaN investigated at the nanoscale

Nearly lattice matched Al0.84In0.16N/AlN/GaN heterostructures have a high potential to be used in HEMTs because of their ability to provide high electron mobility [1] and high 2D electron gas density [2]. However, microscopical electrical properties and morphology have not been deeply investigated up to now. Here we report the characterization of MOCVD grown Al0.84In0.16N/AlN/GaN heterostructures using Atomic force microscopy and conductive-Atomic force microscopy. We have used Atomic Force Microscopy for topography maps and conductive atomic force microscopy to obtain the current-maps at nanoscale. A bias is applied to the Atomic Force Microscopy conductive tip and the resulting current is mapped over the selected area. The analyses of these current maps allow for understanding the current flow in these structures. Figure 1 shows an example of a topography map over one of the described structure. By varying the applied bias to the tip a current-voltage characteristic is obtained which allows for the study of the electronic transport mechanism in these heterostructures. By using Fowler-Nordheim tunnelling model for the conduction mechanism in the metal (tip) oxide semiconductor (MOS) system the electronic transport mechanism has been explained. References: [1] Jinqiao Xie, Xianfeng Ni, Mo Wu, Jacob H. Leach, Ümit Özgür, and Hadis Morkoç, APPLIED PHYSICS LETTERS 91 (2007) 132116 [2] M. Gonschorek, J.F. Carlin, E. Feltin, M. A. Py, N. Grandjean, V. Darakchieva, B. Monemar, M. Lorenz, and G. Ramm, JOURNAL OF APPLIED PHYSICS 103, (2008) 093714