Recently, a research team from Xiamen University has made significant progress in the field of deep ultraviolet light-emitting diodes (DUV LEDs). Their important findings, "Plasmonic omni-directional reflective pads for enhanced light extraction in sub-250 nm deep-ultraviolet light-emitting diodes," were published in the internationally renowned journal *Photonics Research*. The corresponding author of the paper is Jun Yin from Xiamen University. The team comprises members from the School of Physics Science and Technology, the Ministry of Education Engineering Research Center for Micro-Nano Optoelectronic Materials and Devices, the Peng Danling Institute of Micro-Nano Science and Technology, and the Tan Qixiang Innovation Laboratory (FDIX) at Xiamen University. This research innovatively embeds an array of plasmonic omnidirectional reflective pads and uniformly distributed n-type contact rods within a p-GaN layer, significantly improving the light extraction efficiency of deep ultraviolet light-emitting diodes (DUV LEDs) below 250 nm, providing crucial technological support for the development of this field.
(a) Schematic diagram of a deep ultraviolet flip-chip light-emitting diode (LED) below 250nm using distributed n-type contact rods and embedded plasmonic pads to improve light extraction efficiency; (b) Schematic diagram of the photon propagation modulation mechanism of the plasmonic pads; (c) Comparison of simulated current-voltage (I-V) curves of the device with plasmonic pads and the control group device; (d) Comparison of current distribution of the control group and the plasmonic device (D = 8μm) at 100mA, with black arrows indicating the direction and magnitude of current flow in the two-dimensional plane; (e) Variation of average current density in the active layer with the size of the plasmonic pads, and comparison with the area ratio of the plasmonic pads to the active layer; (f) Comparison of surface emission intensity of the control group and the plasmonic device (D = 8μm); (g) Variation of light extraction efficiency (LEE) with the size of the plasmonic pads and related enhancements. The insets in (d) and (f) show detailed views of typical areas in the corresponding figures, with red arrows indicating the plasmonic pads.
(a)Electroluminescence (EL) spectra of plasmonic deep ultraviolet light-emitting diodes (DUV LEDs) with different plasmonic pad sizes compared to a control device without plasmonic pads in the p-GaN layer. (b) Optical output power distributions of a batch of plasmonic devices based on plasmonic pads of different sizes (D = 8, 16, 20, and 24 μm), compared with control devices. (c) Typical current-voltage (I-V) curves and optical output power (LOP) curves of control and plasmonic deep ultraviolet light-emitting diodes with different plasmonic pad sizes; (d) Corresponding angular emission patterns of the devices shown in (c).
