Structural and electrical properties of AlGaN/GaN heterostructures grown on 2°-off-axis 4H–SiC epilayers

This paper reports on the structural and electrical properties of AlGaN/GaN heterostructures grown onto 2°-off-axis silicon carbide (4H–SiC) epitaxial layers. The quality of the grown heterostructures was assessed by a combination of different analytical techniques, revealing a density of conductive dislocations in the order of 1 × 109 cm−2. Electrical characterizations of test patterns and transistors provided insights into the transport properties in the two-dimensional electron gas channel, demonstrating a high current density and a field effect mobility (μFE) of about 1800 cm2/Vs. The temperature dependence of μFE allowed us to identify optical phonon scattering as the dominant transport mechanism in the system at high temperature. In addition to demonstrating the suitability of 2°-off-axis 4H–SiC epilayers for the growth of functional AlGaN/GaN high electron mobility transistors, these results provide useful insights for device manufacturers aiming at the monolithic integration of novel GaN devices onto SiC epitaxial layers.