Microscale light-emitting diodes (µLEDs) have been extensively employed for solid-state lighting applications. However, the ratio of the sidewall area to the emitting area increases as the pixel size of µLEDs decreases, which increases the non-radiative recombination probability on the sidewall surface and eventually degrades the performance of µLEDs. In this study, we investigate the nature of chemical bonds at the sidewall/passivation layer interface using three passivation materials (SiO2, Al2O3, and Si3N4), to identify the underlying mechanism of passivation and thereby achieve high-performance InGaN-based µLEDs. According to the X-ray photoelectron spectroscopy results, the ratio of Ga[sbnd]O bonds on the sidewall/passivation layer interface to Ga[sbnd]N bonds varies with the passivation layer (1.1, 1.06, and 0.33 for SiO2, Al2O3, and Si3N4, respectively). This amount is a key factor affecting the passivation and directly influences the µLED performance. The µLED with SiO2 passivation exhibits a 39% higher light output power and 192% higher current density compared to those associated with the µLED with Si3N4 passivation. These results indicate that the suppression of non-radiative defects depends on the chemical states at the sidewall/passivation layer interface. The findings can provide guidance for optimizing the device performance of µLEDs by selecting appropriate passivation layers.
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation (NRF) grant (No. 2016R1A3B 1908249 ) funded by the Korea government .
© 2022 Elsevier B.V.
- Microscale light-emitting diodes
- Non-radiative recombination
- Passivation layer
- Sidewall defects
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Surfaces and Interfaces