Effect of AlN spacer layer thickness on AlGaN/GaN/Si Schottky barrier diodes

AlGaN/GaN Schottky barrier diodes (SBDs) are popularly demonstrated on 6-in. silicon substrate for next generation motor drive and power supply applications. The epitaxial structures with various inserted AlN spacer layer thicknesses have been investigated using the device DC, reverse recovery time and low-frequency noise (LFN) characteristics. The fabricated SBD with 2.0 nm AlN spacer layer realized the highest breakdown voltage of 274 V without edge termination together with the lowest on-resistance (R_ON) of 2.75 mΩ-cm² than the SBDs with AlN 0.0 nm and AlN 1.5 nm designs. The fabricated SBD with 2.0 nm AlN spacer layer also demonstrated the fast reverse recovery time of 22.6 nS and lower reverse recovery charge of 4.2 nC. Additionally, lower level of LFN characteristic was obtained in SBD with 2.0 nm AlN spacer layer at 300 K and 500 K due to the better carrier confinement in two dimensional electron gas (2DEG) channel. These results suggest that the SBD with 2.0 nm AlN spacer layer is one of the most promising designs for high speed and high-power rectifier circuit applications.