Deep-ultraviolet light-emitting diodes (DUV-LEDs) based on AlGaN alloys are promising for applications in water purification, air sterilization, and portable disinfection. However, their efficiency remains constrained by two intrinsic challenges: inefficient p-type doping and severe electron leakage, which limit carrier utilization and external quantum efficiency (EQE). Here, we propose a systematic tunnel junction (TJ)-mediated carrier regulation strategy by engineering both the spatial position and thickness of the TJ within AlGaN DUV LEDs. Six TJ configurations are comparatively investigated through band-structure simulations and carrier transport analysis, revealing that a 10 nm TJ inserted at the hole supply layer (HSL)/p-GaN interface (Structure E) provides the optimal balance between electron confinement and hole injection. In this configuration, the n+ layer of the TJ introduces an additional 579 meV electron-blocking barrier, while the p+-n+ junction establishes a 430 meV ultrathin tunneling pathway for efficient hole injection, leading to enhanced carrier overlap and radiative recombination in the multiple quantum wells. As a result, Structure E achieves a peak EQE of 6.3%, representing a 117% improvement over the reference structure, and delivers an optical output power of 24 mW at 100 mA, approximately 3.5 times higher than that of the reference device, while maintaining suppressed efficiency droop at high injection currents. Furthermore, increasing the TJ thickness beyond 30 nm induces an exponential reduction in tunneling probability, resulting in deteriorated hole injection and reduced radiative recombination. This work establishes a quantitative correlation between nanoscale TJ engineering, carrier transport regulation, and macroscopic device performance, providing a general design framework for high-efficiency AlGaN-based deep-ultraviolet.
Birefringent metasurfaces supporting ENZ-plasmon polaritons enable tailored, polarization-dependent nanoscale light-matter interactions. We demonstrate a coupled ENZ- plasmon polariton platform using asymmetric gold cross-nanoantennas and an ultrathin ITO film near its ENZ wavelength of 1415 nm. The asymmetric cross-antennas induce structural birefringence, resulting in distinct plasmonic resonances for orthogonal polarizations that hybridize with the ENZ mode via localized near-field coupling. The strong coupling reduces the spectral separation between polarization-dependent resonances by about threefold in the presence of an ENZ layer, compared with antennas on glass. These findings establish ENZ coupling as a way to engineer birefringent polaritonic responses around telecom wavelengths.
