Vertical GaN Junction Barrier Schottky Diodes by Mg Implantation and Activation Annealing

Vertical GaN Junction barrier Schottky (JBS) diodes are fabricated on hydride vapor phase epitaxy (HVPE) GaN substrates. The p-type JBS gridded regions were formed by selective area doping by Mg ion implantation followed by an activation anneal. Implantation was performed into a 10 mu m thick unintentionally doped GaN layer grown by metal organic chemical vapor deposition (MOCVD). Evaporating Pd/Au formed the anode contacts and the cathode was formed of Ti/Al/Ni/Au. Activation of the Mg-implanted GaN was achieved by implementing a three part process, which includes: 1) capping the GaN surface with sputtered AlN, 2) annealing in a 350 PSI nitrogen overpressure environment, and 3) performing a multi-cycle rapid thermal anneal (MRTA) with a peak temperature of 1350 degrees C. In addition to the JBS structures, Schottky barrier diodes (SBDs) and PiN diodes were also fabricated.