Breaking the transverse-magnetic polarized light emission bottleneck of AlGaN LED using nano-patterned substrates and Al reflector

Ultraviolet light-emitting diodes based on Al-rich AlGaN semiconductors operating in the 210 nm-280 nm have drawn significant interest for many critical applications, including water purification, disinfection of air and surface as preventive measures of SARS COV-2, sterilization, etc. However, for the above-mentioned applications, the current technology still relies on toxic and inefficient mercury-based UV lamps. Driven by the immense need for an efficient, mercury-free, compact alternative technology, future water purification and disinfection technologies require the development of high-efficiency UV-C light-emitting diodes. To date, the external quantum efficiency (EQE) in AlGaN quantum well (QW) UV-LED heterostructures has been severely limited due to several factors including large densities of defects/dislocations, extremely low light extraction efficiency (LEE) of dominant transverse magnetic (TM) light, absorptive p -GaN contact, and total internal reflection (TIR).