Local electroluminescence and time-resolved photoluminescence study of InGaN light-emitting diodes

Uniformity of luminescence properties in blue InGaN light-emitting diodes has been studied and analyzed by local time-resolved photoluminescence and microelectroluminescence measurements at different biasing. For studied structures, some nonuniform distribution of photoluminescence properties has been observed at reverse biasing conditions. This nonuniformity revealed inhomogeneous distribution of electric field over the active region. It is supposed that nonuniform distribution of acceptors concentration in p-GaN is a source of electric field fluctuations. Microelectroluminescence measurements showed that areas with locally lower acceptor concentration in p-GaN layer emit lower electroluminescence intensity. This was caused by limited hole injection efficiency into multiple quantum wells region at high current.