We report measurements of the Schottky barrier height of Ni contacts on Ga-polarity n- Al0.08 Ga0.92 N as a function of pressure. With applied hydrostatic pressure, Al0.08 Ga0.92 N Schottky diodes show a decrease in the forward bias current, and correspondingly an increase in the barrier height, which is approximately twice as large as that previously reported for Schottky contacts on Ga-polarity n-GaN. The observed change in barrier height with pressure is attributed to a combination of band structure and piezoelectric effects. The larger change of barrier height for Al0.08 Ga0.92 N can be explained by its larger piezoelectric constants and smaller density of interface states at the metal-semiconductor interface compared to GaN.
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The authors acknowledge partial support from NSF/ECS and NASA/JPL. Support from a Fulbright grant, CIES, IIE, IRPA RMK-8 Strategic Research grant, University of Minnesota, and Universiti Sains Malaysia is also gratefully acknowledged.