Presentation Information

[22p-13M-5]Simultaneous Influence of nanoPSS and Photonic Crystal on the Temporal Light Extraction in Transparent AlGaN UVB LEDs

〇Muhammad Ajmal Khan1, Eriko Matsuura1, Yukio Kashima1, Hideki Hirayama1 (1.RIKEN Cluster for Pioneering Research (CPR))


AlGaN,UVB LED,Photonic Crystal

The inactivation of multidrug resistant organisms (MROs) including fungus (Candida Auris) and bacteria (MERSA). 700,000 patients worldwide die every year from an infection with multidrug resistant organisms (MROs) and such infections can be suppressed using AlGaN UVB LED and Far-UVC LED. Recently, we investigated the influence of Al-graded p-type multi-quantum-barrier electron-blocking-layer (Al-grad p-MQB EBL) and Al-graded p-AlGaN hole source layer (HSL) on the generation and injection of 3D holes in the active region of LED. As a result, remarkable improvement in the external-quantum-efficiency (EQE) of 10% and light power of 42 mW was achieved. However, a very low light extraction efficiency (LEE) of <15% when compared to InGaN blue LEDs (>89%). To improve the LEE, therefore, we propose a highly reflective photonic crystal (HR-PhC) for a p-type AlGaN contact-layer and nanoPSS in the UVB LED prior to the crystal growth. To see the real time influence of nanoPSS and PhC on the optical performance of UVB LED simultaneously, the temporal behaviour of the cross-sectional electric (E)-field mappings were investigated. Quite high light extraction at 83 fs was observed in nanoPSS (LEE = 18.1%). Similarly, the temporal behaviour of cross-sectional E-field mappings of UVB LED with nanoPSS and PhC, where high light extraction at 30 fs was observed in PhC (LEE = 150%). Consequently, when the simultaneous influence of already optimized nanoPSS as well as optimized PhC (Hole-type) in p-AlGaN contact-layer of UVB LED with order of diffraction (m) = 3,4, height = 150 nm, and R/a = 0.40 were implemented the light extraction was remarkably enhanced to approximately 150%.
[1]. M. Ajmal Khan et al. “Progress and Outlook of 10% Efficient AlGaN-Based (290-310 nm)-Band UVB LEDs;
[2]. M. Ajmal Khan, Sci Rep 12, 2591 (2022).