Selective Annealing Effects of Asymmetric Schottky-Type AlGaN Metal-Semiconductor-Metal UV-B Sensor

We proposed and fabricated AlGaN/GaN-based asymmetric Schottky-type metal-semiconductor-metal (MSM) ultraviolet (UV) photodiode with as-deposited Ti/Al/Ni/Au and Ni/Au as Schottky contact metal schemes. Ti/Al/Ni/Au electrode was annealed locally by using the electrical breakdown of a sacrificial insulator. We investigated the electrical and optical characteristics of devices before and after the local annealing. After the selective annealing, the dark current at -1.7 V bias and the UV to visible rejection ratio (UVRR) at -5 V bias were 2.4×10-12 A/cm2 and 527, which were improved remarkably compared to dark current of 4.05×10-10 A/cm2 and UVRR of 86 before annealing.