Investigation on external quantum efficiency droops and inactivation efficiencies of AlGaN-based ultraviolet-c LEDs at 265-285 nm

The temperature-dependent external quantum efficiency (EQE) droops of 265 nm, 275 nm, 280 nm, and 285 nm AlGaN-based ultraviolet-c light-emitting diodes (UVC-LEDs) differed in Al contents have been comprehensively investigated. The modified ABC model (R = An + Bn (2) + Cn (3)) with the current-leakage related term, f(n) = Dn (4), has been employed to analyze the recombination mechanisms in these UVC-LED samples. Experimental results reveal that, at relatively low electrical-current levels, the contribution of Shockley-Read-Hall (SRH) recombination exceeds those of the Auger recombination and carrier leakage. At relatively high electrical-current levels, the Auger recombination and carrier leakage jointly dominate the EQE droop phenomenon. Moreover, the inactivation efficiencies of 222 nm excimer lamp, 254 nm portable Mercury lamp, 265 nm, 280 nm, and 285 nm UVC-LED arrays in the inactivation of Escherichia coli have been experimentally investigated, which could provide a technical reference for fighting against the new COVID-19.

Automated summary

The temperature-dependent external quantum efficiency (EQE) droop of AlGaN-based UVC-LEDs with different Al contents at wavelengths of 265 nm, 275 nm, 280 nm, and 285 nm was comprehensively investigated. The recombination mechanisms in these UVC-LED samples were analyzed using the modified ABC model, revealing that the contribution of Shockley-Read-Hall recombination exceeds those of Auger recombination and carrier leakage at low electrical-current levels. At high electrical-current levels, Auger recombination and carrier leakage jointly dominate the EQE droop phenomenon. Experimental investigation of the inactivation efficiencies of various UVC light sources against Escherichia coli provides a technical reference for combating COVID-19.