Enhanced wall plug efficiency of AlGaN-based deep-UV LEDs using Mo/Al as p-contact

P-type contacts with a high reflectivity in the ultraviolet spectral region made of molybdenum/aluminum (Mo/Al) on AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) emitting at 265 nm have been investigated. Optimized Mo/Al contacts are shown to have a high optical reflectivity above 75 % at 265 nm. DUV LEDs with an absorbing p-AlGaN heterostructure operated at 20 mA show a 15 % higher light output power and a 1 V lower voltage when Mo/Al instead of Pt is used as p-contact. The effect on the voltage of DUV LEDs with a UV-transparent p-side heterostructure is similar. Moreover, DUV LEDs with a Mo/Al contact show a lower operation voltage compared to LEDs with an indium tin oxide/aluminum (ITO/Al) p-contact where the ITO is intended to form a semitransparent low-resistance contact and the Al serves as a reflector.