Effects of Temperature on Current Crowding of GaN-Based Light-Emitting Diodes

The effects of temperature on the current crowding of GaN-based light-emitting diodes (LEDs) were investigated. At 300 K, LEDs fabricated with transparent ITO contacts on the p-layer (ITO-LEDs) showed a larger effective active area ratio (
A
_r
) of 0.69, compared to 0.57 for LEDs fabricated with a reflective Ag contact. However, the
A
_r
for ITO-LEDs decreased more rapidly with increasing temperature (0.28 at 440 K) than that for Ag-LEDs (0.31) due to the ITO-LEDs' higher junction temperature associated with a larger series resistance, resulting in a consistent and rapid drop of optical output power.