Barrier height enhancement of Al_x Ga_1-x NGaN schottky diodes prepared by P₂ S₅ (NH₄)₂ S treatments

The passivation of modulation-doped Al0.1 Ga0.9 NGaN Schottky surfaces by treatment with (NH4) 2 S and P2 S5 (NH4) 2 S has been investigated. The current-voltage (I-V) curves of these Schottky diodes demonstrate that the TiPtAu- Al0.1 Ga0.9 NGaN Schottky diodes prepared by P2 S5 (NH4) 2 S treatment have the lowest reverse-leakage current (7.5 nA cm2) and the highest Schottky-barrier height (0.98 eV). Detailed X-ray photoelectron spectroscopy analysis indicates that a thin sulfide layer on the samples with the (NH4) 2 S treatment has an improvement for these favorable characteristics. Further, a thin phosphide layer on the samples with the P2 S5 (NH4) 2 S treatment exhibits a larger improvement on the Schottky-barrier height and the reverse-leakage current.