Comparative study of electroluminescence efficiency of blue (In,Ga)N and red GaAs quantum well diodes

摘要

Electroluminescence (EL) efficiency of a bright blue (In,Ga)N quantum-well (QW) diode has been studied in comparison with a high quality GaAs QW diode over a wide temperature range and as a function of current. For the red diode the EL intensity increases in directly proportional to the current at 20 K, indicating a nearly unity external quantum efficiency, although the EL efficiency is influenced by the transport of electrically injected carriers and nonradiative processes at higher temperatures. For the blue diode, however, the room temperature EL efficiency is surprisingly high, although the low-temperature EL efficiency is found to be quite low at high injection and significantly varied with current. These variations of the EL efficiency with current and temperature for the blue diode are attributed to the carrier capture and escape processes influenced under the internal piezo-field effects as a function of forward bias voltage.