Scanning Probe Microscopy nanoscale electrical characterization of AlGaN/ GaN grown on structured GaN templates

Scanning Capacitance Microscopy (SCM), Scanning Surface Potential Microscopy (SSPM) and Scanning Spreading Resistance Microscopy (SSRM) techniques are applied to perform investigation of AlGaN/GaN heterostructures epitaxially grown on spatially structured GaN templates used for quasi vertical high electron mobility transistors (VHEMT) fabrication. The heterogeneity of electrical properties in this structures was observed that might be caused by structural defects in AlGaN barrier, with density varying in different regions of the sample. SCM one point spectroscopy measurements confirmed the existence of two dimensional electron gas (2DEG) at AlGaN/GaN interface on the slope of the transition region between reactive ion etched and unetched areas under the transistor channel. Electrical parameters of 2DEG in slope region do not differ significantly from those determined for the other areas of the sample.