  Carrier recombination and transport processes play key roles in determining
the optoelectronic performances such as the efficiency droop and forward
voltage in InGaN/GaN multiple-quantum-well (MQW) light-emitting diodes (LEDs).
In this work, we investigate the dominant carrier transport and recombination
processes inside and outside the MQW region as a function of injection current
from a new point of view by separately examining the carrier energy loss.
Analysis of the measurement results reveals that the carrier accumulation and
subsequent spill-over from the MQW active region to the clad is the most
probable mechanism of explaining the efficiency and forward voltage variation
with the injection current.
