Recovering the efficiency of AlGaInP red micro-LEDs using sidewall treatments
Matthew S. Wong, Ryan C. White, Stephen Gee, Tanay Tak, Srinivas Gandrothula, Hyoshik Choi, Shuji Nakamura, James S. Speck, Steven P. DenBaars
Abstract
Abstract A sidewall treatment process is proposed to recover the external quantum efficiency (EQE) loss in AlGaInP micro-LEDs ( μ 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 × 100 to 20 × 20 μ m 2 . This work reveals that AlGaInP μ LEDs can be energy efficient by employing proper sidewall treatments.