Schottky diodes on GaN (gallium nitride) semiconductors

The electrical characteristics of Au and Ni Schottky barriers on n-type GaN grown by gas phase molecular beam epitaxy were investigated. Capacitance-Voltage and Current-Voltage techniques were used to calculate the barrier height, carrier concentration and ideality factor. Two different processing techniques, one-mask and two-mask process, were used to fabricate the Schottky diodes. An electron gun evaporator was used to deposit the metal contacts on the n-type GaN surface. The metal contacts were deposited at a pressure of 10^-8 Torr.

Using the one-mask process, the forward current ideality factor was 1.01 and 1.20 for Au/n-GaN and Ni/n-GaN Schottky diodes, respectively. The Capacitance-Voltage and Current-Voltage measurements show that the barrier height was 1.2 eV and 0.9eV for Au/n-GaN and 1.12 eV and 0.91 eV for Ni/n-GaN Schottky diodes, respectively.

Using the two-mask process, the forward current ideality factor was 1.30 and 1.02 for Au and Ni Schottky diodes, respectively. The Capacitance-Voltage and Current-Voltage measurements show that the barrier height was 2.02 eV and 0.85eV for Au/n-GaN and 2.30 eV and 0.86 eV for Ni/n-GaN Schottky diodes, respectively.