Performance Optimization of Au-Free Lateral AlGaN/GaN Schottky Barrier Diode With Gated Edge Termination on 200-mm Silicon Substrate

In this paper, a further leakage reduction of AlGaN/GaN Schottky barrier diodes with gated edge termination (GET-SBDs) has been achieved by optimizing the physical vapor deposited TiN as the anode metal without severe degradation of ON-state characteristics. The optimized GET-SBD multifinger power diodes with 10 mm anode width deliver similar to 4 A at 2 V and show a median leakage of 1.3 mu A at 25 degrees C and 3.8 mu A at 150 degrees C measured at a reverse voltage of -200 V. The temperature-dependent leakage of Si, SiC, and our GaN power diodes has been compared. The breakdown voltage (BV) of GET-SBDs was evaluated by the variation of anode-to-cathode spacing (LAC) and the length of field plate. We observed a saturated BV of similar to 600 V for the GET-SBDs with LAC larger than 5 mu m. The GET-SBD breakdown mechanism is shown to be determined by the parasitic vertical leakage current through the 2.8 mu m-thick buffer layers measured with a grounding substrate. Furthermore, we show that the forward voltage of GET-SBDs can be improved by shrinking the lateral dimension of the edge termination due to reduced series resistance. The leakage current shows no dependence on the layout dimension LG (from 2 to 0.75 mu m) and remains at a value of similar to 10 nA/mm. The optimized Au-free GET-SBD with low leakage current and improved forward voltage competes with high-performance lateral AlGaN/GaN SBDs reported in the literature.