Toward High Wall-Plug Efficiency in Nanowire-Based Red Micro-LEDs

Displays for future technologies such as augmented and virtual reality require ultrahigh resolution and efficient power consumption. While micro-LEDs can attain the required sizes for these displays, at present, their efficiencies are severely lacking, especially the red-emitting ones. Here, we show that by utilizing a combination of strategies for enhancing the carrier injection efficiencies, including nitrogen polarity, Mg-doped AlGaN electron-blocking layer, and a p-GaN layer with gradient doping, unprecedentedly high wall-plug efficiency for a submicron red LED has been achieved. Light-emitting diodes with submicrometer dimensions exhibited an emission wavelength of ∼650 nm, reaching a peak external quantum efficiency of ∼12.3%, and a wall-plug efficiency of ∼11.4%, corresponding to a peak electrical efficiency of ∼92%. Through this work, we demonstrate that the hitherto low electrical efficiency of nanowire-based devices can be overcome through careful design of the device heterostructure and that such devices can form the foundation of future micro-LED displays.