Enhancement of the Schottky barrier height using a nitrogen-rich tungsten nitride thin film for the schottky contacts on AlGaN/GaN heterostructures

Abstract

Tungsten, stoichiometric W2N, and nitrogen-rich W2N films were used as Schottky contacts on AlGaN/GaN heterostructures. The nitrogen content in the film was controlled by varying the nitrogen-to-argon gas flow ratio during the reactive sputter deposition. The diode with the nitrogen-rich film exhibited a higher Schottky barrier height and the leakage current was comparable to that of the Ni/Au Schottky contact. Analysis suggested that this was due to the increase of the tungsten nitride work function as the result of higher nitrogen incorporation. Furthermore, after 600 degrees C thermal annealing, the diode was stable and showed no change in the leakage current.