Polarization engineering of InAlN/GaN HFET and the effect on DC and RF performance

We demonstrate InAIN/GaN based heterostructure field effect transistor (HFET), which allow us to engineer the polarization induced charges, and improve the DC and RF characteristics over conventional nitride-based transistors. The In_xAl_1-xN/GaN heterostructures were grown on sapphire substrates by metal-organic vapor phase epitaxy (MOVPE) with In content of 4% to 15%, and characterized by X-ray photoemission spectroscopy (XPS) and X-ray diffraction (XRD). HFET devices with gate length of 0.7 μm were fabricated and their DC to RF characteristics show a reduction in current collapse with the increase of In content. Channel transport analysis is conducted using temperature-dependent Hall effect measurements and RF delay analysis.