Scanning Microwave Microscopy for Electronic Device Analysis on Nanometre Scale

Probing electrical properties of state-of-the-art electronic devices is one of the key features of Scanning Microwave Microscopy. While providing valuable information on charge carrier properties, the combination of an atomic force microscope cantilever with a microwave signal raises the question on the actual spatial resolution of the system. On the example of the highly confined two-dimensional electron gas of an AlGaN/GaN structure, the effective tip radius is demonstrated to be in the range of the theoretical tip radius for sharp tips, while both values differ for unevenly shaped cantilever tips. The presented method demonstrates the role of the microwave excitation region for the spatial resolution of the system as well as the potential of this method to characterise the effective tip radius.