Performance on GaN-Based Light-Emitting Diodes with Different Substrate Tilt Angles

The electrostatic discharge (ESD) performance of GaN-based light-emitting diodes (LEDs) with naturally-textured p-GaN contact layers grown on c-axis miscut sapphire substrates are studied. During machine model tests, the device grown on a 0.35 degrees miscut sapphire shows the highest ESD tolerance, while the one grown on a 0.2 degrees miscut sapphire exhibits the poorest tolerance. It is discovered that this effect correlates with the presence of maximum capacitance (C-m) values, over the difference in defect densities between LEDs. The variation in C-m values is caused by parasitic capacitance effect induced by different p-GaN surface morphologies between the studied devices. This observation gives us more reliable application in improving ESD performance based on the device grown on a 0.35 degrees miscut sapphire.