Leakage-current reduction and improved on-state performance of Au-free AlGaN/GaN-on-Si Schottky diode by embedding the edge terminations in the anode region

AlGaN/GaN Schottky barrier diodes (SBDs) have been fabricated on GaN-on-Si wafers (8-inch) with Au-free CMOS compatible technology. Two types of Edge Terminations have been investigated to suppress the leakage current with the conventional AlGaN/GaN Schottky Barrier Diodes fabricated on the same wafer as a reference. The External Edge Terminated-SBD (EET-SBD) shows a trend of reduction in leakage current by scaling down the spacing between the edge termination and the Schottky contact. By embedding the edge terminations inside the anode region named Gated Edge Terminated-SBD (GET-SBD), four orders of magnitude reduction in leakage current has been observed experimentally compared with the reference. Furthermore, anode recess was performed and its influences on both on-and off-state characteristics were studied. The recessed EET-SBD shows lower leakage current than the non-recessed one. The forward voltage drop in EET-SBD appears to be degraded by recess. The recessed GET-SBD features the lowest leakage (1 mu A/mm at V-AC of -600 V) and improved on-state performance (with V-F of 1.15 V). With Anode-to-Cathode distance (LAC) of 10 mu m, a breakdown voltage over 600 V in all three architectures has been achieved in both recessed and non-recessed wafers. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim