Intense ultraviolet electroluminescence properties of the high-power InGaN-based light-emitting diodes fabricated on patterned sapphire substrates

The electroluminescence and photoluminescence characteristics of high-efficient InGaN multi-quantum-well ultraviolet light-emitting diodes have been investigated, There appeared a single emission band in the electroluminescence spectra at about 3.235 eV with a band width of 90 meV at room temperature under direct current. With increasing forward Current, the luminescence intensity was not saturated. and increased linearly with increasing injection current Up to 50 mA. Under pulsed current conditions at room temperature, the luminescence intensity increased linearly with increasing injection current up to I WO mA. and a shift of the electroluminescence peak position was not observed. These result,, indicated that the injected carriers were confined efficiently in the active layer, and also suggested the possibility of realizing ultraviolet laser diodes. It was revealed that the forward-biased electroluminescence spectrum at 4 K reflected the distribution of hot electrons injected into the active layer. The maximum temperature of hot electrons was estimated to be about 350 K under a forward-biased Pulsed current of about 500 mA. which was much higher than the lattice temperature.