ABOVE 2 A/mm DRAIN CURRENT DENSITY OF GaN HEMTS GROWN ON SAPPHIRE

Abstract

We report on the investigation of an InAlN/GaN HEMT structure, delivering higher sheet carrier density than the commonly used AIGaN/GaN system. We achieved in a reproducible way more than 2 A/mm maximum drain current density for a gate length of 0.25 μm with unpassivated undoped devices realized on sapphire substrates. Small signal measurements yield a F T = 31 GHz and F MAX = 52 GHz , which illustrates the capability of these structures to operate at high frequencies. Moreover, the pulsed analysis indicates a more stable surface in the case of AlInN than that of AlGaN , attributed to the lattice matched growth of this barrier with 17% In content on GaN , avoiding strain piezo polarization in the material.