The effects of slanted mesa sidewall on p-n junction GaN-Based LEDs

Typically, most of the commercially available GaN-based LEDs (Light Emitting Diodes) are grown on sapphire as their substrates. Due to the insulating substrate, lateral current injection is employed so that the anode and cathode contacts are in side-by-side configuration. During the etching process, the possibility of slanted mesa sidewall to form is higher. In this work, the influence of slanted mesa sidewall are studied while its light emitting area size and contacts position are maintained. The comparison for optical output power, current-voltage, thermal dissipation and distribution characteristics of different angles of slanted mesa sidewall are performed. Angles of slanted mesa sidewall are varied from angle-in and angle-out with reference to 90 degrees at mesa edge. The simulation results revealed that with the increment of slanted angle, the LEDs performed better due to improved overall emission intensity and uniform current distribution of the devices. The angled sidewalls efficiently deflect photons that are initially guided laterally within the GaN epilayer in the off-surface direction. As such, devices showed better overall performance.