Enhancement of the Optical Output Power of InGaN/GaN Multiple Quantum Well Light-Emitting Diodes by a CoFe Ferromagnetic Layer

We report the increase of the optical output power of InGaN/GaN multiple quantum well (MQW) flip-chip blue light-emitting diodes (LEDs) using cobalt–iron (CoFe) ferromagnetic layers. The CoFe alloy layer is deposited on a p-ohmic reflector of the flip-chip LEDs to apply a magnetic field in the MQWs. The optical output power of LEDs with a CoFe layer after magnetization is increased by 23% at an injection current of 20 mA compared with LEDs that have a CoFe layer before magnetization. The time-resolved photoluminescence spectra and magnetic field simulations indicated that the improvement of the optical output power of the LEDs is attributed to an enhanced radiative recombination rate in the MQWs by the additional drift of carriers in the MQWs due to the gradients of the magnetic field of the CoFe ferromagnetic layer.