Ru/N-polar GaN Schottky diode with less than 2 μA/cm2 reverse current

In this letter, we report the Schottky barrier diode investigation of ruthenium (Ru) deposited by atomic layer deposition on N-polar GaN. The Schottky diodes showed near-ideal thermionic current behavior under forward bias and reverse bias at various temperatures. The barrier height values extracted from both regions agreed well at each temperature and the barrier was extracted to be 0.77 eV at room temperature. The combination of the 0.77 eV barrier and thermionic current characteristic resulted in $\mu \text{A}$ /cm2 reverse current at −5 V, which is a record-low value for N-polar GaN Schottky diodes. As a comparison, the Ru on Ga-polar GaN Schottky barrier diode, which has a barrier height of 1.0 eV, exhibited a ~ two-order of magnitude higher leakage than Ru on N-polar GaN at −5 V due to other parasitic leakage mechanisms.