Thermionic emission conduction in Mo AlGaN/GaN diodes in the presence of Schottky barrier inhomogeneities

Wide bandgap semiconductors for high-power and high-frequency applications drain a lot of scientific interest. Among them AlGaN/GaN heterostructure with its related 2D electron gas is a key element for advanced microelectronics devices. Nonetheless, Schottky contacts on AlGaN/GaN heterostructure typically show a non- ideal behavior due to concomitant conduction mechanisms and high ideality factor. This study investigates the electrical behavior of molybdenum Schottky contacts on AlGaN/GaN heterostructures grown on silicon, focusing on the temperature dependence of the electrical parameters. Despite limited adoption of molybdenum as a Schottky metal, its application result in a contact that exhibits a conduction dominated by thermionic emission (TE) with an ideality factor of 1.26 at room temperature. This conduction behavior, uncommon for AlGaN/GaN Schottky contacts, enabled a detailed analysis of the barrier inhomogeneities. The concentration of inhomogeneities justifying the observed electrical behavior is 2 × 10⁹ cm^{- 2}, in good agreement with the density of dislocations in the heterostructure.