Evidence of localization effects in InGaN single-quantum-well ultraviolet light-emitting diodes

The importance of doping or alloying with In for obtaining high external qu antum efficiency was shown for GaN-based single-quantum-well (SQW) structur es in terms of localization effects due to quantum-disk (Q-disk [M. Sugawar a, Phys. Rev. B 51, 10743 (1995)])-size potential minima in the QW plane. T he ultraviolet light-emitting diode with lightly In-alloyed InGaN SQW exhib ited an electroluminescence peak from the band-tail states. Monochromatic c athodoluminescence mapping images of In0.03Ga0.97N SQW indicated the presen ce of Q-disk-size effective bandgap variation. Furthermore, cubic InGaN QW which does not suffer from the piezoelectric field normal to the QW plane, also exhibited a broad band-tail. (C) 2000 American Institute of Physics. [ S0003-6951(00)01413-3].