Barrier Height Enhancement of Al[sub x]Ga[sub 1−x]N∕GaN Schottky Diodes Prepared by P[sub 2]S[sub 5]∕(NH[sub 4])[sub 2]S Treatments

Abstract

The passivation of modulation-doped Al 0.1 Ga 0.9 N/GaN Schottky surfaces by treatment with (NH 4 ) 2 S and P 2 S 5 /(NH 4 ) 2 S has been investigated. The current-voltage (I-V) curves of these Schottky diodes demonstrate that the Ti/Pt/Au-Al 0.1 Ga 0.9 N/GaN Schottky diodes prepared by P 2 S 5 /(NH 4 ) 2 S treatment have the lowest reverse-leakage current (7.5 nA/cm 2 ) 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 (NH 4 ) 2 S treatment has an improvement for these favorable characteristics. Further, a thin phosphide layer on the samples with the P 2 S 5 /(NH 4 ) 2 S treatment exhibits a larger improvement on the Schottky-barrier height and the reverse-leakage current.