Optical analysis of III-nitride micro-light-emitting diodes with different sidewall treatments at low current density operation

In this work, the optical efficiency of III-nitride blue micro-LEDs (mu LEDs) ranged from 5 x 5 to 60 x 60 mu m2 with different sidewall treatments at low current density range was investigated. The results showed dielectric sidewall passivation using atomic layer deposition (ALD) has superior optical enhancement compared to conventional RF sputtering, where most of the enhancement occurred at low current density range. Additionally, the use of ALD sidewall passivation and chemical treatment offered significant efficiency improvement for different sizes of mu LEDs at operating less than 1 A cm-2 and the devices without sidewall treatments did not emit light. The effect of sidewall treatments to the effective Shockley-Read-Hall (SRH) nonradiative recombination coefficient, or the effective A coefficient from the ABC model, was estimated. The effective SRH nonradiative recombination coefficient was suppressed by two orders of magnitude for devices with sidewall treatments compared to devices without sidewall passivation.