Temperature dependence of current-voltage characteristics of Ni–AlGaN/GaN Schottky diodes

Abstract

Ni–AlGaN/GaN Schottky barrier diodes (SBDs) with lateral geometry were fabricated on sapphire substrates. At 300 K, devices with 500-μm-diameter Schottky contacts exhibited breakdown voltage (VB) of 765 V, forward current (IF) of 0.065 A at 1.5 V, and specific on-resistance (Ron) of 81.3 mΩ cm2, producing a figure-of-merit (VB2/Ron) of ∼7.2 MW cm−2. Measured in multifinger patterns, the same parameters were 420 V, 3.2 A, 4.6 mΩ cm2, and 38.4 MW cm−2, respectively, at 300 K. With the increase in measurement temperature from 300 to 450 K, SBDs with dimensions of 3000×3000 μm2 showed larger effective barrier heights (0.8 eV at 300 K and 1.27 eV at 475 K) and a slightly negative temperature coefficient (−0.48 V K−1) for reverse breakdown voltage, while there was a little change in reverse leakage current. These results show the strong influence of barrier height inhomogeneity on the temperature dependence of apparent barrier heights obtained through current-voltage measurements.