AlN/GaN HEMT technology with in-situ SiNx passivation

We report on the fabrication of low resistance Ohmic contacts on AlN/GaN HEMT material terminated with in-situ SiNx. The AlN/GaN material was grown on SiC substrate using metal organic chemical vapor deposition (MOCVD), and employs a 5nm in-situ SiNx layer to reduce the cracking of the highly stressed AlN layer. A low Ohmic contact resistance of 0.4 Ω.mm was achieved, and this is one of the lowest reported values. 2×200 μm finger AlN/GaN HEMT devices exhibited a maximum drain current density, IDSS, of 700 mA/mm, which in comparison with standard AlGaN/GaN HEMT devices (on SiC) was at least 2× higher.