Improvement of external quantum efficiency in InGaN-based double-heterostructure light-emitting diodes

The improvement in efficiency droop was investigated by using an InGaN-based, double-heterostructure (DH) active region. The external quantum efficiency (EQE) is improved by 89.3% at a current density of 200 A/cm ² by inserting a 20-nm-thick p-type AlGaN as the electronblocking layer (EBL). The interface states created between the DH active region and EBL might be responsible for the effective level through the other suggested mechanisms besides the Auger loss. The redshift phenomenon of the electroluminescence (EL) peak wavelength is attributed to the bandgap renormalization, although the detailed mechanism associated with the efficiency droop remains unknown.