Selective Ohmic Contact Formation on Schottky Type AlGaN/GaN UV Sensors Using Local Breakdown

Local annealing method was developed to change the Ni-AlGaN/GaN and Ni-GaN rectifying contacts into ohmic contacts by using the dielectric breakdown of a sacrificial insulator. The current increased 10⁵ times in an AlGaN/GaN Schottky diode as a result of the annealing step. An interdigitated Schottky metal-semiconductor-metal ultraviolet (UV) sensor was fabricated using the locally annealed electrodes. The UV to visible rejection ratio of the GaN-based UV sensor was 5.2 at forward bias to 467.9 at a reverse bias of -1 V. Unlike typical annealing methods, the local annealing method will be useful to change the contact property on the probing stage even after finishing the whole fabrication processes.