  In this paper, we aim to understand the apparent characteristics of IQE and
I-V curve in AlGaInP and InGaN LED devices. For the analysis, we separate the
current into radiative current and non-radiative current component by using the
information of IQE. We carefully analyze each current component by ideality
factor, S parameter, and the modified Shockley diode equation which is suitable
for LED device. Through the analyses, it has been found that the
characteristics of respective current components are basically similar for both
samples while the physical origin of the potential drop induced by radiative
current and the amount of double injection current induced non-radiative
current by are different. Compared with AlGaInP LEDs, the InGaN LEDs have
higher degrees of electron overflow initiated by low recombination rate in
active region, causing both the efficiency droop and the higher operating
voltage. To remedy this, the radiative recombination rate and/or the active
volume should be increased further.
