Effects of Annealing on Electrical Characteristics and Current Transport Mechanisms of the Y/p-GaN Schottky Diode

This study investigates the effects of annealing on the electrical properties and current transport mechanism of Y/p-GaN Schottky barrier diodes (SBDs). We found no significant change in the surface morphology of the Y Schottky contacts during the annealing process. The Schottky barrier height (SBH) of the as-deposited Y/p-GaN SBD was estimated to be 0.95 eV (I–V)/1.19 eV (C–V). The SBH increased upon annealing at 400°C and 500°C, and then decreased slightly with annealing at 600°C. Thus the maximum SBH of the Y/p-GaN SBD was achieved at 500°C, with values of 1.01 eV (I–V)/1.29 eV (C–V). In addition, the SBH values were estimated by Cheung’s, Norde, and Ψ_s-V plots and were found to be in good agreement with one another. Series resistance (R_S) values were also calculated by I–V, Cheung’s, and Norde functions at different annealing temperatures, with results showing a decrease in the interface state density of the SBD with annealing at 500°C, followed by a slight increase upon annealing at 600°C. The forward-bias current transport mechanism of SBD was investigated by the logI–logV plot at different annealing temperatures. Our investigations revealed that the Poole–Frenkel emission mechanism dominated the reverse leakage current in Y/p-GaN SBD at all annealing temperatures.