Effect of annealing temperature on the electrical and structural properties of V/p-GaN Schottky structures

• Annealing effects on electrical and structural properties of V/p-GaN SBD are studied.
• Maximum barrier height is obtained on V/p-GaN SBD upon annealing at 400 °C.
• Interface state density decreases with increasing annealing temperature up to 400 °C.
• Electrical results are correlated with the interfacial microstructure of the contacts.
• Nitride interfacial phases are responsible for increase in BH after annealing at 400 °C.

The electrical and structural properties of V/p-GaN Schottky barrier diode (SBD) have been investigated as a function of annealing temperature. The Schottky barrier height (SBH) of the as-deposited contact is found to be 0.82 eV (I–V) and 1.10 eV (C–V). However, it is noted that the SBH increases for the contact annealed at 400 °C and the values are 0.94 eV (I–V) and 1.21 eV (C–V). Further, with increasing annealing temperature up to 500 °C, the SBH decreases to 0.92 eV (I–V) and 1.19 eV (C–V). Also, the rectification ratio of the V/p-GaN SBD is evaluated for as-deposited and annealed contacts. The electrical parameters of the V/p-GaN SBD are also discussed with Cheung's and Norde functions. It is noted that the interface state density decreases upon annealing at 400 °C and then slightly increases after annealing at 500 °C. Results reveal that the superior electrical characteristics are obtained for the contact annealed at 400 °C. The electrical results are also correlated with the interfacial microstructure of the contacts. The AES and XRD results reveal that the formation of nitride phases at the interface may be the reason for the increase of SBH after annealing at 400 °C. The formation of gallide phases at the interface may be reason for the decrease in the SBH.