9 September 2021
Red InGaN μLEDs for displays
University of California Santa Barbara (UCSB) in the USA suggests that indium gallium nitride (InGaN) red micro-sized light-emitting diodes (μLEDs) could provide a solution for displays [Panpan Li et al, Appl. Phys. Lett., v119, p081102, 2021].
Although the high indium content leads to relatively low external quantum efficiency (EQE) compared with commercial aluminium indium gallium phosphide (AlInGaP) regular-size LEDs, which can reach 20-30%, the UCSB research shows that the InGaN devices maintain their ~2.5% EQE as the dimensions scale down to the tens of microns level.
The researchers comment on the AlGaInP μLED EQE: “This is caused by the SRH [Shockley-Read-Hall] carrier injection loss due to a higher surface recombination velocity of AlInGaP, which is related to the fundamental property of the materials and difficult to overcome.” The SRH mechanism is the major non-radiative recombination route at low current density.
The team also points out that μLED display proposals suggest the need for 5μmx5μm red-emitters with 5% EQE, adding “we believe that InGaN red μLEDs would have large potentials for such efficiencies.”
Tags: Red InGaN μLEDs AlInGaP InGaN MOCVD
The author Mike Cooke is a freelance technology journalist who has worked in the semiconductor and advanced technology sectors since 1997.