Surface recombination in III-nitride LEDs: negligible or important?

There is ongoing interest in the fabrication of micro-pixel light-emitting diodes (LEDs) and LED arrays in view of their potential application in Li-Fi communication technology. Reduction of the LED dimensions necessary for this brings into play physical effects that have not been considered before as critical ones for the device performance. In particular, surface recombination has been known for a long time as an essential channel of carrier losses in AlGaInP-based LEDs, lowering their efficiency of the chip sizes as small as a few hundred microns. Surprisingly, this mechanism was never regarded as a valuable factor capable of affecting the efficiency of blue and green III-nitride LEDs.