Optical and electrical characterizations of micro-LEDs grown on lower defect density epitaxial layers
Srinivas Gandrothula, Takeshi Kamikawa, Pavel Shapturenka, Ryan Anderson, Matthew S. Wong, Haojun Zhang, James S. Speck, Shuji Nakamura, Steven P. DenBaars
Abstract
We have fabricated μLEDs of mesa sizes 10 × 10 and 15 × 15 μm2 on native (2021¯) semipolar substrates and on epitaxial lateral overgrown (ELO) wings of the (2021¯) substrate. The ELO μLEDs exhibited very low leakage current (less than 10−10 A) under forward bias (V < 2 V) and at reverse bias voltages, which was a reduction in several orders of magnitude when compared with planar μLEDs under the same fabrication and sidewall passivation scheme. Electrical characterization revealed that the mesa sidewall is less damaged in plasma dry etching in the ELO μLEDs due to a lower material defect density than the planar μLEDs. Moreover, the ELO μLEDs showed improved optical performance over the planar μLEDs.