Effect of hydrostatic pressure on the barrier height of Ni Schottky contacts on n-AlGaN

We report measurements of the Schottky barrier height of Ni contacts on Ga-polarity n-Al0.08Ga0.92N as a function of pressure. With applied hydrostatic pressure, Al0.08Ga0.92N 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 Al0.08Ga0.92N can be explained by its larger piezoelectric constants and smaller density of interface states at the metal-semiconductor interface compared to GaN.