Recovering the efficiency of AlGaInP red micro-LEDs using sidewall treatments

A sidewall treatment process is proposed to recover the external quantum efficiency (EQE) loss in AlGaInP micro-LEDs (& mu;LEDs). The proposed sidewall treatment consists of thermal annealing, ammonium sulfide chemical treatment, and sidewall passivation using atomic-layer deposition (ALD). The devices with sidewall treatment show improved optical power of more than 500% and 190% at 5 and 100 A cm(-2), respectively, compared to devices with ALD sidewall passivation. The reduction in EQE was 20% when shrinking the device dimensions from 100 x 100 to 20 x 20 & mu;m(2). This work reveals that AlGaInP & mu;LEDs can be energy efficient by employing proper sidewall treatments.