Presentation Information
[9a-N205-2]Demonstration of (219–221 nm)-Band Extreme-far-UVC LEDs on c-Sapphire
〇(P)Amina Yasin1, Yuki Nakamura1, M. Nawaz Sharif1, M. Ajmal Khan1, Hideki Hirayama1 (1.RIKEN)
Keywords:
AlGaN based Extreme-far-UVC LEDs,external quantum efficiency,i-AlGaN
Far-Ultraviolet-C AlGaN-based light-emitting diodes (LEDs) emitting below 230 nm are gaining significant attention for their potential to safely inactivate viruses in public spaces without harming humans. However, achieving high efficiency at wavelengths below 230 nm, remains a major challenge. Taniyasu et al. reported the external quantum efficiency (EQE) of on-wafer device on the order of ~0.000001%, which is still lower than that for typical on wafer UVB LEDs (EQE ≈ 10%). To enable practical disinfection systems while suppressing the harmful part of the spectral range longer than 230 nm, the development of shorter-wavelength LEDs (219–222 nm) with improved performance is highly desirable. In this study, we report the fabrication and optimization of AlGaN-based far-UVC LEDs with peak wavelengths at 219, 220, and 221 nm. To improve emission efficiency, we optimized the epitaxial structure by engineering the n-type AlGaN layers and introducing an intrinsic AlGaN (i-AlGaN) layer followed by a multi-quantum well (MQW) active region. To isolate the role of the i-AlGaN layer, we also fabricated LEDs using only the i-AlGaN layer (without MQW) as the active region. Devices were grown on AlN/c-sapphire templates using metal-organic chemical vapor deposition. By changing the Al composition in the i-AlGaN layer to 90.5%, 90%, and 88.7%, the emission peaks were successfully tuned to 219 nm, 220 nm, and 219 nm, respectively. Structural and compositional optimizations of the i-AlGaN and MQW active region led to improved internal quantum efficiency and electron injection efficiency. The EQEs of the fabricated LEDs, measured under continuous-wave operation at room temperature, were 0.0017% (219 nm), 0.009% (221 nm with only i-AlGaN) and 0.012% (221 nm) with corresponding output powers of 0.01 mW, 0.008 mW, and 0.002 mW at 20 mA. These results highlight a promising approach toward realizing efficient extreme-far-UVC LEDs suitable for safe and effective viral disinfection.