Evidence map›Paper›PMID 40481052›Full record

ArticleScientific reports2025

Simultaneous influence of nanoPSS and photonic crystal on light extraction in AlGaN 304nm UVB LEDs.

M Ajmal Khan, Eriko Matsuura, Yukio Kashima, Hideki Hirayama

Abstract read
In one paragraph

Article in Scientific reports, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

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Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Review
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

4 authors.

M Ajmal KhanRIKEN Pioneering Research Institute (PRI), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. muhammad.khan@riken.jp.
Eriko MatsuuraRIKEN Pioneering Research Institute (PRI), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
Yukio KashimaRIKEN Pioneering Research Institute (PRI), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
Hideki HirayamaRIKEN Pioneering Research Institute (PRI), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

The external-quantum efficiency (EQE) of AlGaN-based ultraviolet-B light-emitting diodes (UVB LEDs) has achieved a world record value of 9.6% on wafers but suffers from a low light extraction efficiency (LEE) of < 15%, notably lower than that of the LEE of InGaN blue LEDs (> 89%). This study employed the finite-difference time-domain (FDTD) method to explore how micro-patterned c-plane Sapphire substrates (microPSS) or nano-patterned c-plane Sapphire substrates (nanoPSSs) and reflecting photonic crystals (R-PhCs) influence light scattering in flip-chipped AlGaN-based UVB LEDs, with or without an Al-side reflector. First, various microPSS and nanoPSS shapes (Pillar-like and Hole-like) were analysed by the FDTD to optimise the pitch (a), diameter (d), height (h), and diffraction order (m) under Bragg's condition. The nanoPSS were found most effective for UVB LEDs at an emission peak of 304 nm with cylindrical Hole-like nanoPSS (m = 10, d = 596 nm, a = 746 nm, h = 500 nm, R/a = 0.38), (R is the radius of the holes of the nanoPSS or PhC) improving LEE enhancement to the maximum possible value of approximately 18%. Next, an Al-side reflector was introduced to evaluate the combined impact of optimised nanoPSS and R-PhC (Hole-like) on theoretical light extraction. Parameters (m = 3; h = 150 nm; R/a = 0.40) applied in p-GaN or p-AlGaN contact layers boosted light extraction to approximately 148% or 150% (with an Al-side reflector) and approximately 120% (without an Al-side reflector), marking significant theoretical and experimental advancements in AlGaN UVB LED efficiency.

Indexed as

AlGaNBragg’s condition; plane-wave-expansion (PWE) methodFemtosecond (fs)Finite-difference time-domain method (FDTD)Light extraction efficiency (LEE)Micro-patterned sapphire substrate (microPSS)Nano-patterned c-plane Sapphire substrate (nanoPSS)Photonic band gap (PBG)Pulsed sourceUltraviolet-B light-emitting diode (UVB LED)

Identifiers

PMID40481052
PMCPMC12144251

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.