CONTRIBUTION OF ZONE FLUCTUATION POTENTIAL AND DISORDERING OF HETEROBOUNDARIES TO THE DECREASED EFFICIENCY OF NITRIDE-BASED LEDS

The zone fluctuation potentials (ZFPs) in quantum wells located in the space charge region (SCR) of the p-n junction and the lateral ZFPs in quantum wells outside the SCR in blue, green, and UV LEDs based on nitrides have been experimentally determined. Green LEDs were used as an example to show that the low external quantum efficiency (EQE) of LEDs at the maximum correlated with an increase in the ZFP and disordering of heteroboundaries in quantum wells located in the SCR. The EQE at the maximum decreased because charge carriers were captured by charged centers localized at disordered heteroboundaries. The lateral ZFP in quantum wells located outside the SCR was the main parameter determining the decrease of the EQE from the moment the p-n junction opened until current densities reached 30-40 A/cm(2).