Dependence of leakage current in Ni/Si₃N₄/n-GaN Schottky diodes on deposition conditions of silicon nitride

Metal-insulator-semiconductor (MIS) GaN-based Schottky diodes with an ultra-thin in situ deposited Si₃N₄ dielectric are fabricated and characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The leakage current of the reverse biased diodes is found to depend strongly on Si₃N₄ deposition temperature, with an activation energy of 7.3 eV, and reactor atmosphere (N₂ versus H₂). The dependence is attributed to point defects originating from the deviation of Si₃N₄ from stoichiometric composition. Deposition of Si₃N₄ at low temperatures is shown to substantially suppress the leakage current. The effective barrier heights in the MIS Schottky diodes are also affected by Si₃N₄ deposition conditions and, in particular, by the deposition temperature. (paper)