Interplay of sidewall damage and light extraction efficiency of micro-LEDs

This Letter describes the impact of shape on micro lightemitting diodes (mu LEDs), analyzing 400 mu m(2) area mu LEDs with various mesa shapes (circular, square, and stripes). Appropriate external quantum efficiency (EQE) can yield internal quantum efficiency (IQE) which decreases with increasing peripheral length of the mesas. However, light extraction efficiency (eta(e)) increased with increasing mesa periphery. We introduce analysis of J(peak) (the current at peak EQE) since it is proportional to the non-radiative recombination. Etching the sidewalls using tetramethylammonium hydroxide (TMAH) increased the peak EQE and decreased the sidewall dependency of J(peak). Quantitatively, the TMAH etching reduced non-radiative surface recombination by a factor of four. Hence, shrinking mu LEDs needs an understanding of the relationship between non-radiative recombination and eta(e) where analyzing J(peak) can offer new insights. (C) 2022 Optica Publishing Group