Optical and microstructural characterization of Micro-LED with sidewall treatment

Abstract

The traditional influence on the sidewall damage of Micro-LED was mostly focused on the research of I-V-L. In this paper, we discussed the influence of Micro-LED sidewall damage from the perspective of optical and microstructural characterization. Scanning electron microscopy showed that the Micro-LED structure with smaller size was more irregular after inductively coupled plasma etching. High-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy analysis showed that the area of the upper and lower regions of the quantum well was inconsistent, there was about 2 nm lattice disorder on the surface of the sidewall of the mesa, and oxygen and silicon impurity atoms were enriched. For optical characterization, a method combining laser scanning confocal microscopy and photoluminescence (PL) was proposed to evaluate the optical performance of the mesa. The results showed that the luminescence of Micro-LED mesa was uneven, the luminous intensity at the edge of the mesa was reduced by more than 65%, and the luminous wavelength was shifted by several nanometers. Finally, we optimized the sidewall treatment process, effectively improved the performance of Micro-LED devices by combining tetramethylammonium hydroxide treatment and SiO2 passivation, and increased the luminous intensity of Micro-LED 2 μm away from the edge by about 4.7 times and PL uniformity was greatly improved. These results provided an available reference for the development of Micro-LED.