Radiative and nonradiative recombination processes in ultraviolet light-emitting diode composed of an In0.02Ga0.98N active layer

Radiative and nonradiative recombination processes have been studied in ult raviolet In0.2Ga0.98N light-emitting diodes (LEDs), by employing photoinduc ed voltage, electroreflectance, and time-resolved photoluminescence spectro scopy. It was found that excitons in the In0.02Ga0.98N active layer are wea kly localized at low temperature, and delocalized above about 70 K, showing a three-dimensional feature in the temperature dependence of the radiative lifetime. The external quantum efficiency (eta(ext)) of this LED is about ten times higher than the LED whose active layer is composed of GaN. Improv ement of the eta(ext) value by the addition of a small amount of In to the active layer is attributed to the suppression of the density of the nonradi ative recombination center (NRC), as well as possibly to where the origin o f the NRC is changed. (C) 1999 American Institute of Physics. [S0003-6951(9 9)01504-1].