  The current-voltage characteristic and ideality factor of III-Nitride quantum
well light-emitting diodes (LEDs) grown on bulk GaN substrates are
investigated. At operating temperature, these electrical properties exhibit a
simple behavior. A model in which only active-region recombinations have a
contribution to the LED current is found to account for experimental results.
The limit of LED electrical efficiency is discussed based on the model and on
thermodynamic arguments, and implications for electroluminescent cooling are
examined.
