Observation of Enormous Non-Linearities in the Output Electroluminescence Characteristics of Room-Temperature GaN-Based Microcavities

Highly non-linear light (λ ~ 380 nm)-current characteristics are observed in a bulk GaN-based laterally-emitting microcavity diode at room temperature. The value of the non-linear slope, when plotted in a double logarithmic scale, increases from ~ 2 to ~ 40 at the threshold (~ 5 kA/cm2). The spectral characteristics remain essentially invariant with increasing excitation and no signatures of coherence are observed at any injection. Control measurements indirectly show that the electroluminescence originates from the p-type Mg:doped GaN contact layer. These phenomena are at least partially and qualitatively similar to previous observations of super-linear photoluminescence characteristics in Zn:doped GaN epilayers at ~ 180 K [1]. In our case, the super-linearity originates, most possibly, due to the redistribution of injected carriers between the radiative and non-radiative pathways over a particular excitation regime. Further analysis of these effects is in progress and will be presented.


[1] M. A. Reshchikov, A. J. Olsen, M. F. Bishop, and T. McMullen, Phys. Rev. B 88, 075204 [2013].