Measurements were made of the electrical and optical properties of blue light-emitting diodes that were based upon III-V nitrides. The current-voltage characteristics were described by a relationship of the form, I = Ioexp[V], where  was temperature-independent. This suggested the operation of a process of conduction via tunnelling. The differences between blue and blue-green devices were explained by taking account of the tunnelling process across semiconductor interfaces at which large numbers of defects were present. The light output intensity, as a function of junction-voltage, revealed that radiative recombination occurred via deep levels that were located in the forbidden gap. It was concluded that the non-radiative centers saturated at very low current values which were comparable to the values at which this saturation took place in light-emitting diodes that were based upon III-V arsenides with a low defect content.

I.Mártil, E.Redondo, A.Ojeda: Journal of Applied Physics, 1997, 81[5], 2442-4