Enhanced light extraction efficiency of micropixel geometry AlGaN DUV light-emitting diodes

Floyd, Richard; Gaevski, Mikhail; Hussain, Kamal; Mamun, Abdullah; Chandrashekhar, M. V. S.; Simin, Grigory; Khan, Asif

doi:10.35848/1882-0786/ac0fb8

Cited by 42 publications

(25 citation statements)

References 37 publications

(46 reference statements)

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“…Here we summarize the EQE of AlGaN micro-LEDs and conventional LEDs in the UV spectral range (200-400 nm), see Fig. 2 [13,14,[18][19][20][21][22][23][24][25][26][27]. To date, most researches mainly focus on the diverse applications of UV micro-LEDs, but relatively few works have investigated the improvement of EQE achievable with UV micro-LEDs.…”

Section: A Current State Of the Art And Challenges Of Uv Micro-ledsmentioning

confidence: 99%

“…In the UVC band, researchers in University of Science and Technology of China (USTC) fabricated UV LEDs emitting at ∼275 nm with different sizes of 300, 200, 100, 50, and 20 µm and they found that the peak EQE of a 20 µm micro-LED with a value of 1.2%, increased by 20% compared to that of a 300 µm micro-LED [13]. Also, University of South Carolina (USC) has reported a 5 µm micro-LED with a record brightness of 570 Wcm −2 and the peak EQE is ∼2% [18]. At present, for a conventionally sized LED in the UVC region, RIKEN has reported a record high EQE of ∼20% for UVC LED emitting at 275 nm [20].…”

Section: A Current State Of the Art And Challenges Of Uv Micro-ledsmentioning

confidence: 99%

“…2. EQEs of typical UV LEDs including conventional large size UV LEDs and UV micro-LEDs [13,14,[18][19][20][21][22][23][24][25][26][27]. The sizes of the respective devices are given alongside the data points.…”

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confidence: 99%

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AlGaN Ultraviolet Micro-LEDs

Tian

Shan

Zhu

et al. 2022

IEEE J. Quantum Electron.

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AlGaN-based UV LEDs have proven to have broad applications in many fields including sterilization, disinfection, purification, and phototherapy, but the performance still needs to be further improved. Benefiting from advantages such as better current spreading, lower self-heating effect and higher light extraction efficiency achieved by the reduced LED size, UV micro-LEDs are expected to improve quantum efficiency and thus can expand more potential applications. In this article, performance enhancement techniques and applications of UV micro-LEDs will be reviewed, providing an outlook for further development of AlGaN-based UV-LEDs. The micro-LED format offers possibilities to address fundamental issues that UV LEDs confront in general, but also demonstrates specific characteristics and performance advantages opening up new areas of application including high-speed optical communication, time-resolved fluorescence lifetime measurement, optical pumping, direct writing and charge management.

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Section: A Current State Of the Art And Challenges Of Uv Micro-ledsmentioning

confidence: 99%

Section: A Current State Of the Art And Challenges Of Uv Micro-ledsmentioning

confidence: 99%

See 1 more Smart Citation

AlGaN Ultraviolet Micro-LEDs

Tian

Shan

Zhu

et al. 2022

IEEE J. Quantum Electron.

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“…10 As the R/G/B QDs show higher absorption efficiency to lower wavelength photons, blue-violet and near-UV micro-LEDs were proposed to improve the color rendering and increase the excitation efficiency. 11,12 While the research on AlGaN-based deep-ultraviolet (deep-UV) micro-LEDs is still challenging, 13,14 few efforts were invested in its application as an excitation source to R/G/B QDs. 15 In this work, we focused on the AlGaN-based deep-UV micro-LED as a high-efficiency excitation source for QD display.…”

Section: Introductionmentioning

confidence: 99%

AlGaN multiple quantum well deep‐ultraviolet micro‐light‐emitting diodes for high color conversion efficiency quantum dots display

et al. 2022

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Displays based on inorganic micro-light-emitting diodes (micro-LEDs) are highly anticipated for next-generation technologies. AlGaN-based deepultraviolet (deep-UV) micro-LED as the excitation source for quantum dots display with high efficiency was reported in this paper. To achieve optimized electro-optical performance, deep-UV micro-LEDs with different electrodes were fabricated and analyzed in sizes from 200 Â 200 to 10 Â 10 μm 2 . At the same forward bias, the devices with Ti/Al-based electrodes achieved 10 times injection current and three times electroluminescence intensity than those with Cr/Al-based electrodes. The blueshift phenomenon of deep-UV light was observed from 292 nm at 2 A/cm 2 to 287 nm at 200 A/cm 2 with the increasing current density. By the excitation of deep-UV micro-LED, quantum dot film achieved high light conversion efficiency and optimized color rendering, as the converted color emission peak was separate from the pumping source. The high energy of deep-UV photons and the narrow emission bandwidth of QDs resulted in prominent color purity. The forward voltage and electroluminescence intensity uniformity of a 250 Â 250 micro-LED array with each pixel size of 30 Â 30 μm 2 were further discussed. The optical microscope images of green QD film pumped by a deep-UV micro-LED demonstrated its competitive application in the color-converted display.

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“…In this regard, various electrode structures, such as Ni/Mg [8], mesh p-GaN/ITO [12], Mo/Al [13], and Cu nanowires [14] have been used to solve the issues related to ohmic contact with the p-(Al)GaN layer while minimizing DUV light absorption through the electrode. In addition, device structures have been redesigned using AlN/h-BN heterostructures [1], GaN/AlN quantum-disk nanorods [15], Graded AlGaN alloy structures [16], wavy quantum well [17], UVB micro-LED [18], and micropixel DUV LED [19] to further improve the quantum efficiencies of DUV LEDs. Despite these efforts, the EQE values of AlGaN-based top-emitting DUV LEDs (even with tunnel heterojunctions) reported thus far do not exceed 2.8% [20]- [24].…”

Section: Introductionmentioning

confidence: 99%

High-Efficiency and High-Reliability Deep-UV Light-Emitting Diodes Using Transparent Ni-Implanted AlN Ohmic Electrodes

et al. 2021

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Significant efforts have been devoted to improve the external quantum efficiency (EQE) of AlGaN-based top-emitting deep-UV light-emitting diodes (DUV LEDs). However, issues such as ohmic contact and challenges related to p-AlGaN doping and growth have hampered advancement. In this paper, a record-high EQE of 3.2% is reported for AlGaN-based lateral-type top-emitting DUV LEDs in which Nidoped AlN (Ni:AlN) DUV-transparent ohmic electrodes are used. The ohmic electrode exhibits a transmittance of more than 90% at 280 nm and a reasonably good ohmic behavior with the p-Al0.64Ga0.36N contact layers. The Ni:AlN-based DUV LED demonstrates outstanding performance (i.e., operating voltage of 8.3 V at 20 mA, light output power of 11.6 mW at 100 mA) relative to the conventional thin ITO-and Ni/Au-based DUV LEDs. Furthermore, the proposed device is highly reliable, as evidenced by the fact that it maintained more than 80% of its light output power after 500 h of operation, and the operating voltage increased by only 2.7% over the operating time of 1 × 10 5 s. INDEX TERMSDeep ultraviolet, Light emitting diodes, Electrical doping process, Transparent conductive electrode.

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Enhanced light extraction efficiency of micropixel geometry AlGaN DUV light-emitting diodes

Cited by 42 publications

References 37 publications

AlGaN Ultraviolet Micro-LEDs

AlGaN Ultraviolet Micro-LEDs

AlGaN multiple quantum well deep‐ultraviolet micro‐light‐emitting diodes for high color conversion efficiency quantum dots display

High-Efficiency and High-Reliability Deep-UV Light-Emitting Diodes Using Transparent Ni-Implanted AlN Ohmic Electrodes

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