Current crowding and optical saturation effects in GaInN/GaN light-emitting diodes grown on insulating substrates

Abstract

Current crowding in mesa-structure GaInN/GaN light emitting diodes (LEDs) grown on insulating substrates is analyzed. A model developed reveals an exponential decrease of the current density with distance from the mesa edge. Devices with stripe-shaped mesa geometry display current crowding and a saturation of the optical output power at high injection currents. It is shown that the optical power saturation depends on the device geometry. It is also shown that saturation is less pronounced in LEDs employing a ring-shaped mesa geometry, which reduces current crowding, as compared to the conventional square-shaped mesa geometry.