Inhomogeneous Light Emission From the Vertical Structured Blue Micro-LEDs

By using microscopic hyperspectral imaging, the inhomogeneous electroluminescence (EL) across the mesa of blue vertical micro-LEDs has been investigated. The sidewall emission dominates the EL of micro-LEDs under higher current injections and that bright circular light emission from the sidewall region possesses larger peak energy due to the strain relaxation. The multi-channel radiative recombination leads to the high-energy peaks in the EL spectra of the inner and dim regions of mesa. The photons, which are generated in the inner region of mesa and transported to sidewall after experiencing multiple reflections, act as the indispensable component for sidewall emissions. This work emphasizes the importance of spatially resolved spectral characterization in revealing the mechanisms of light emission from sidewall of micro-LEDs.