Light Emission\nfrom the Sidewall Region Dominates\nthe Spectral Broadening of InGaN-Based Red Micro-LEDs

InGaN-based red microlight-emitting diodes (micro-LEDs)\nhave demonstrated\nsuperiority in monolithic integration microdisplays, and red micro-LEDs\ngrown on silicon substrates are cost-efficient and potentially compatible\nwith pixel driving schemes; however, the spectral broadening and inhomogeneous\nlight emission would greatly limit their applications. Herein, to\nimprove the performance of InGaN-based red micro-LEDs, the origin\nof the spectral broadening and the inner physics of the local light\nemission from InGaN-based red micro-LEDs grown on silicon substrates\nwere demonstrated via microscopic hyperspectral imaging. The bright\ncircular light emission with a shorter wavelength from the sidewall\nregion of the micro-LEDs is mainly due to the carrier recombination\nin localized states, which can result in a deviation of the perceived\ncolor. The localization can be attributed to the fluctuation in the\nwell thickness, hindering the realization of a uniform red emission.\nThe results further suggest that reasonable strategies to mitigate\nthe spectral broadening effect from the sidewall region of micro-LEDs\nare significant for achieving efficient InGaN-based red micro-LEDs\nwith a high perceived color quality.