Abstract
In this study, high power GaN p-i-n diodes are grown on pattern sapphire substrates (PSSs) by metal organic chemical vapor deposition (MOCVD) and fabricated to quasi-vertical structure. The intrinsic layer (i-layer) has conductivity modulation in high level injection resulting in decreasing the forward series resistances at forward bias. When a negative bias is applied, i-layer of GaN p-i-n diode could support high reverse voltage. Using the concentration and thickness of i-layer with different epitaxial wafers fabricates devices. The thinner thickness and higher concentration of the i-layer are, the lower forward voltage (VF) and specific on-resistance (RONA) will be. In order to improve reverse characteristics of device, using two-step, field plate and integration of two-step and field plate structures with edge terminations can reduce the leakage current and enhance the breakdown voltage at reverse bias. The thickness 5 μm and concentration 1×1016 cm-3 of i-layer with integration of two-step and field plate structure has the lowest specific on-resistance of 0.59 mΩ-cm2, and breakdown voltage is over 800 V. The corresponding Baliga’s Figure of Merit (BFOM) is over 1 GW/cm2. Finally, depositing aluminum along surface of mesa shades the ultraviolet from device at forward bias, and avoiding the epoxy of package be broken to achieve better reliability of device.