1
|
Hsu YH, Lin XD, Lin YH, Wuu DS, Horng RH. Performance comparison of flip-chip blue-light microLEDs with various passivation. DISCOVER NANO 2024; 19:129. [PMID: 39150592 DOI: 10.1186/s11671-024-04078-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 08/06/2024] [Indexed: 08/17/2024]
Abstract
In this study, arrays of μLEDs in four different sizes (5 × 5 μm2, 10 × 10 μm2, 25 × 25 μm2, 50 × 50 μm2) were fabricated using a flip-chip bonding process. Two passivation processes were investigated with one involving a single layer of SiO2 deposited using plasma-enhanced chemical vapor deposition (PECVD) and the other incorporating Al2O3 deposited by atomic layer deposition (ALD) beneath the SiO2 layer. Owing to superior coverage and protection, the double-layers passivation process resulted in a three-order lower leakage current of μLEDs in the 5 μm chip-sized μLED arrays. Furthermore, higher light output power of μLEDs was observed in each chip-sized μLED array with double layers passivation. Particularly, the highest EQE value 21.9% of μLEDs array with 5 μm × 5 μm chip size was achieved with the double-layers passivation. The EQE value of μLEDs array was improved by 4.4 times by introducing the double-layers passivation as compared with that of μLEDs array with single layer passivation. Finally, more uniform light emission patterns were observed in the μLEDs with 5 μm × 5 μm chip size fabricated by double-layer passivation process using ImageJ software.
Collapse
Affiliation(s)
- Yu-Hsuan Hsu
- Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
| | - Xin-Dai Lin
- Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
| | - Yi-Hsin Lin
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
| | - Dong-Sing Wuu
- Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, Nantou, 54561, Taiwan, ROC
| | - Ray-Hua Horng
- Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC.
| |
Collapse
|
2
|
Park S, Ryu JE, Kim TH, Kim HJ, Bu J, Seo SJ, Baek JH, Hong YJ, Ryu SW, Park Y, Lee MG, Jang HW. Advanced Mechanical Transfer of Micro-LEDs Enabled by Structurally Modified Wide Sapphire Nanomembranes through Thermal Reflow of Photoresist. ACS APPLIED MATERIALS & INTERFACES 2024; 16:42426-42434. [PMID: 39099087 DOI: 10.1021/acsami.4c05958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/06/2024]
Abstract
Micro light-emitting diodes (micro-LEDs) are pivotal in next-generation display technologies, driven by the need for high pixel density. This study introduces a novel methodology utilizing wide sapphire nanomembranes (W-SNM) as a dual-purpose template for high-quality epitaxial growth and the mechanical lift-off of individual micro-LEDs. Micro-LEDs grow individually on W-SNM, obviating the chip singulation process. By employing mechanical fracturing of the thin W-SNM, our method facilitates the transfer of micro-LEDs without the conventional laser lift-off (LLO) process. Previously introduced sapphire nanomembranes (SNM) have shown promise in enhancing epitaxial layer quality; however, they encountered challenges in managing micro-LED size variation and achieving efficient mechanical transfer. Here, we apply simple yet effective adjustments to the SNM structure, specifically, its elevation and widening. This strategic modification allows micro-LEDs to endure applied forces without incurring cracks or defects, ensuring that only the targeted W-SNM are selectively fractured. The mechanically transferred vertical 15 × 15 μm2 micro-LED device operates at an optimal turn-on voltage of 3.3 V. Finite element simulations validate the mechanical strain distribution between the W-SNM and GaN when pressure is applied, confirming the efficacy of our design approach. This pioneering methodology offers a streamlined, efficient pathway for the production and mechanical transfer of micro-LEDs, presenting new avenues for their integration into next-generation, high-performance displays.
Collapse
Affiliation(s)
- Sohyeon Park
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Jung-El Ryu
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tae-Hyun Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Hyuk Jin Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Jeewon Bu
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Sung Jin Seo
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Ji Hyun Baek
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Young Joon Hong
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Sang-Wan Ryu
- Department of Physics, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Yongjo Park
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
- Advanced Institute of Convergence Technology, Seoul National University, Suwon 16229, Republic of Korea
| | - Myoung-Gyu Lee
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Ho Won Jang
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
- Advanced Institute of Convergence Technology, Seoul National University, Suwon 16229, Republic of Korea
| |
Collapse
|
3
|
Nam GB, Ryu JE, Eom TH, Kim SJ, Suh JM, Lee S, Choi S, Moon CW, Park SJ, Lee SM, Kim B, Park SH, Yang JW, Min S, Park S, Cho SH, Kim HJ, Jun SE, Lee TH, Kim YJ, Kim JY, Hong YJ, Shim JI, Byun HG, Park Y, Park I, Ryu SW, Jang HW. Real-Time Tunable Gas Sensing Platform Based on SnO 2 Nanoparticles Activated by Blue Micro-Light-Emitting Diodes. NANO-MICRO LETTERS 2024; 16:261. [PMID: 39112731 PMCID: PMC11306663 DOI: 10.1007/s40820-024-01486-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 07/15/2024] [Indexed: 08/10/2024]
Abstract
Micro-light-emitting diodes (μLEDs) have gained significant interest as an activation source for gas sensors owing to their advantages, including room temperature operation and low power consumption. However, despite these benefits, challenges still exist such as a limited range of detectable gases and slow response. In this study, we present a blue μLED-integrated light-activated gas sensor array based on SnO2 nanoparticles (NPs) that exhibit excellent sensitivity, tunable selectivity, and rapid detection with micro-watt level power consumption. The optimal power for μLED is observed at the highest gas response, supported by finite-difference time-domain simulation. Additionally, we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO2 NPs. The noble metals induce catalytic interaction with reducing gases, clearly distinguishing NH3, H2, and C2H5OH. Real-time gas monitoring based on a fully hardware-implemented light-activated sensing array was demonstrated, opening up new avenues for advancements in light-activated electronic nose technologies.
Collapse
Affiliation(s)
- Gi Baek Nam
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jung-El Ryu
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Laboratory of Electronics, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Tae Hoon Eom
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seung Ju Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Jun Min Suh
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Laboratory of Electronics, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Seungmin Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sungkyun Choi
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Cheon Woo Moon
- Department of Display Materials Engineering, Soonchunhyang University, Asan, 31538, Republic of Korea
| | - Seon Ju Park
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Soo Min Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Byungsoo Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung Hyuk Park
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jin Wook Yang
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sangjin Min
- Department of Photonics and Nanoelectronics, BK21 FOUR ERICA-ACE Center, Hanyang University ERICA, Ansan, 15588, Republic of Korea
| | - Sohyeon Park
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung Hwan Cho
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hyuk Jin Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sang Eon Jun
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Tae Hyung Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yeong Jae Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jae Young Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Young Joon Hong
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Jong-In Shim
- Department of Photonics and Nanoelectronics, BK21 FOUR ERICA-ACE Center, Hanyang University ERICA, Ansan, 15588, Republic of Korea
| | - Hyung-Gi Byun
- Department of Electronics, Information and Communication Engineering, Kangwon National University, Samcheok, 25913, Republic of Korea
| | - Yongjo Park
- Advance Institute of Convergence Technology, Seoul National University, Suwon, 16229, Republic of Korea
| | - Inkyu Park
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.
| | - Sang-Wan Ryu
- Department of Physics, Chonnam National University, Gwangju, 500-757, Republic of Korea.
| | - Ho Won Jang
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
- Advance Institute of Convergence Technology, Seoul National University, Suwon, 16229, Republic of Korea.
| |
Collapse
|
4
|
Cui S, Sun K, Liao Z, Zhou Q, Jin L, Jin C, Hu J, Wen KS, Liu S, Zhou S. Flexible nanoimprint lithography enables high-throughput manufacturing of bioinspired microstructures on warped substrates for efficient III-nitride optoelectronic devices. Sci Bull (Beijing) 2024; 69:2080-2088. [PMID: 38670852 DOI: 10.1016/j.scib.2024.04.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/28/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024]
Abstract
III-nitride materials are of great importance in the development of modern optoelectronics, but they have been limited over years by low light utilization rate and high dislocation densities in heteroepitaxial films grown on foreign substrate with limited refractive index contrast and large lattice mismatches. Here, we demonstrate a paradigm of high-throughput manufacturing bioinspired microstructures on warped substrates by flexible nanoimprint lithography for promoting the light extraction capability. We design a flexible nanoimprinting mold of copolymer and a two-step etching process that enable high-efficiency fabrication of nanoimprinted compound-eye-like Al2O3 microstructure (NCAM) and nanoimprinted compound-eye-like SiO2 microstructure (NCSM) template, achieving a 6.4-fold increase in throughput and 25% savings in economic costs over stepper projection lithography. Compared to NCAM template, we find that the NCSM template can not only improve the light extraction capability, but also modulate the morphology of AlN nucleation layer and reduce the formation of misoriented GaN grains on the inclined sidewall of microstructures, which suppresses the dislocations generated during coalescence, resulting in 40% reduction in dislocation density. This study provides a low-cost, high-quality, and high-throughput solution for manufacturing microstructures on warped surfaces of III-nitride optoelectronic devices.
Collapse
Affiliation(s)
- Siyuan Cui
- Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Ke Sun
- Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Zhefu Liao
- Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Qianxi Zhou
- Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Leonard Jin
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo ON, N2L 3G1, Canada
| | - Conglong Jin
- Jiangxi SMTC Semiconductor Co., Ltd., Nanchang 330096, China
| | - Jiahui Hu
- Jiangxi SMTC Semiconductor Co., Ltd., Nanchang 330096, China
| | - Kuo-Sheng Wen
- Jiangxi SMTC Semiconductor Co., Ltd., Nanchang 330096, China
| | - Sheng Liu
- Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China; The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China.
| | - Shengjun Zhou
- Center for Photonics and Semiconductors, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China; The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China.
| |
Collapse
|
5
|
Chang MK, Jeong S, Kim D, Nam H. Review of Integrated Gate Driver Circuits in Active Matrix Thin-Film Transistor Display Panels. MICROMACHINES 2024; 15:823. [PMID: 39064334 PMCID: PMC11279033 DOI: 10.3390/mi15070823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/24/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024]
Abstract
Many advanced technologies have been employed in high-performance active matrix displays, including liquid crystal displays, organic light-emitting diode displays, and micro-light-emitting diode displays. On the other side, there exists a strong demand for cost reduction, and it is one of the low-cost schemes for integrating the driver circuit in a panel based on thin-film transistor technologies. This paper reviews the overall concept, operation principles, and various circuit approaches in shift registers for scanning pulse generation. In addition, it deals with the implementation of additional functionalities in gate drivers to support pixel compensation, multi-line driving, in-cell capacitive touch screen, pixel sensing, and adaptive scanning region control.
Collapse
Affiliation(s)
- Min-Kyu Chang
- Department of Information Display, Kyung Hee University, Seoul 02447, Republic of Korea; (M.-K.C.); (S.J.)
| | - Seoyeong Jeong
- Department of Information Display, Kyung Hee University, Seoul 02447, Republic of Korea; (M.-K.C.); (S.J.)
| | - Darren Kim
- Harman International, Novi, MI 48377, USA;
| | - Hyoungsik Nam
- Department of Information Display, Kyung Hee University, Seoul 02447, Republic of Korea; (M.-K.C.); (S.J.)
| |
Collapse
|
6
|
Sun X, Yan Y, Kang M, Zhao W, Yan K, Wang H, Li R, Zhao S, Hua X, Wang B, Zhang W, Deng Y. General strategy for developing thick-film micro-thermoelectric coolers from material fabrication to device integration. Nat Commun 2024; 15:3870. [PMID: 38719875 PMCID: PMC11079074 DOI: 10.1038/s41467-024-48346-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/28/2024] [Indexed: 05/12/2024] Open
Abstract
Micro-thermoelectric coolers are emerging as a promising solution for high-density cooling applications in confined spaces. Unlike thin-film micro-thermoelectric coolers with high cooling flux at the expense of cooling temperature difference due to very short thermoelectric legs, thick-film micro-thermoelectric coolers can achieve better comprehensive cooling performance. However, they still face significant challenges in both material preparation and device integration. Herein, we propose a design strategy which combines Bi2Te3-based thick film prepared by powder direct molding with micro-thermoelectric cooler integrated via phase-change batch transfer. Accurate thickness control and relatively high thermoelectric performance can be achieved for the thick film, and the high-density-integrated thick-film micro-thermoelectric cooler exhibits excellent performance with maximum cooling temperature difference of 40.6 K and maximum cooling flux of 56.5 W·cm-2 at room temperature. The micro-thermoelectric cooler also shows high temperature control accuracy (0.01 K) and reliability (over 30000 cooling cycles). Moreover, the device demonstrates remarkable capacity in power generation with normalized power density up to 214.0 μW · cm-2 · K-2. This study provides a general and scalable route for developing high-performance thick-film micro-thermoelectric cooler, benefiting widespread applications in thermal management of microsystems.
Collapse
Affiliation(s)
- Xiaowen Sun
- School of Materials Science and Engineering, Beihang University, Beijing, China
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Yuedong Yan
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China.
| | - Man Kang
- School of Materials Science and Engineering, Beihang University, Beijing, China
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Weiyun Zhao
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Kaifen Yan
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - He Wang
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Ranran Li
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Shijie Zhao
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Xiaoshe Hua
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Boyi Wang
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China
| | - Weifeng Zhang
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China.
| | - Yuan Deng
- School of Materials Science and Engineering, Beihang University, Beijing, China.
- Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province, Hangzhou Innovation Institute of Beihang University, Hangzhou, China.
| |
Collapse
|
7
|
Wang L, Shi S, Yin L, Zhai Y, Xuan T, Liu B, Xie RJ. Water-Soluble Quantum Dots for Inkjet Printing Color Conversion Films with Simultaneous High Efficiency and Stability. ACS APPLIED MATERIALS & INTERFACES 2024; 16:5050-5057. [PMID: 38228493 DOI: 10.1021/acsami.3c13244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Water-soluble quantum dots (QDs) are necessary to prepare patterned pixels or films for high-resolution displays with less environmental burden but are very limited by the trade-off between photoluminescence and stability of QDs. In this work, we proposed synthesizing water-soluble QDs with simultaneous excellent luminescence properties and high stability by coating the amphiphilic poly(maleic anhydride-alt-1-octadecene)-ethanol amine (PMAO-EA) polymer on the surface of silane-treated QDs. These coated QDs show a photoluminescence quantum yield (PLQY) as high as 94%, and they have good photoluminescence stability against light irradiation and thermal attacks, owing to the suppression of the nonradiative recombination by the polymer layer and the isolation of oxygen and water by the silica layer. The water-soluble QDs, mixed with ethylene glycol, enable inkjet printing of QD color conversion films (QD-CCFs) with an average diameter of 68 μm for each pixel and a high PLQY of 91%. The QD-CCFs are demonstrated to fabricate red-emitting mini-LEDs by combining with blue mini-LED chips, which have an external quantum efficiency as high as 25.86% and a luminance of 2.44 × 107 cd/m2. We believe that the proposed strategy is applicable to other water-soluble QDs and paves an avenue for inkjet printing environmentally friendly QD-CCFs for mini/micro-LED displays.
Collapse
Affiliation(s)
- Le Wang
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Shuchen Shi
- Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials, College of Materials, Xiamen University, No. 422, Siming South Road, Xiamen 361005, China
| | - Lu Yin
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Yue Zhai
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Tongtong Xuan
- Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials, College of Materials, Xiamen University, No. 422, Siming South Road, Xiamen 361005, China
- Shenzhen Research Institute of Xiamen University, No. 19, Gaoxin South Fourth Road, Nanshan District, Shenzhen 518000, China
| | - Bo Liu
- Nanjing University of Information Science & Technology, Institute of Optics and Electronics, Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing 210044, China
| | - Rong-Jun Xie
- Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials, College of Materials, Xiamen University, No. 422, Siming South Road, Xiamen 361005, China
- Shenzhen Research Institute of Xiamen University, No. 19, Gaoxin South Fourth Road, Nanshan District, Shenzhen 518000, China
- State Key Laboratory of Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005, China
| |
Collapse
|
8
|
Chu C, Jia Y, Hang S, Chen Y, Jia T, Tian K, Zhang Y, Zhang ZH. Fabricating and investigating a beveled mesa with a specific inclination angle to improve electrical and optical performances for GaN-based micro-light-emitting diodes. OPTICS LETTERS 2023; 48:5863-5866. [PMID: 37966738 DOI: 10.1364/ol.501707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/17/2023] [Indexed: 11/16/2023]
Abstract
In this Letter, beveled mesas for 30 × 30 µm2 GaN-based micro-light-emitting diodes (µLEDs) with different inclination angles are designed, fabricated, and measured. We find that µLED with a mesa inclination angle of 28° has the lowest internal quantum efficiency (IQE) and the highest injection current density at which the peak IQE is obtained. This is due to the increased quantum confined Stark effect (QCSE) at the mesa edge. The increased QCSE results from the strong electric field coupling effect. Instead of radiative recombination, more nonradiative recombination and leakage current will be generated in the sidewall regions. Besides, the smallest angle (28°) also produces the lowest light extraction efficiency (LEE), which arises from the optical loss caused by the sidewall reflection at the beveled surface sides. Therefore, the inclination angle for the beveled mesa has to be increased to 52° and 61° by using Ni and SiO2 as hard masks, respectively. Experimental and numerical results show that the external quantum efficiency (EQE) and the optical power can be enhanced for the fabricated devices. Meanwhile, the reduced surface recombination rate also decreases the leakage current.
Collapse
|
9
|
Kumar V, Kymissis I. MicroLED/LED electro-optical integration techniques for non-display applications. APPLIED PHYSICS REVIEWS 2023; 10:021306. [PMID: 37265477 PMCID: PMC10155219 DOI: 10.1063/5.0125103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 03/20/2023] [Indexed: 06/03/2023]
Abstract
MicroLEDs offer an extraordinary combination of high luminance, high energy efficiency, low cost, and long lifetime. These characteristics are highly desirable in various applications, but their usage has, to date, been primarily focused toward next-generation display technologies. Applications of microLEDs in other technologies, such as projector systems, computational imaging, communication systems, or neural stimulation, have been limited. In non-display applications which use microLEDs as light sources, modifications in key electrical and optical characteristics such as external efficiency, output beam shape, modulation bandwidth, light output power, and emission wavelengths are often needed for optimum performance. A number of advanced fabrication and processing techniques have been used to achieve these electro-optical characteristics in microLEDs. In this article, we review the non-display application areas of the microLEDs, the distinct opto-electrical characteristics required for these applications, and techniques that integrate the optical and electrical components on the microLEDs to improve system-level efficacy and performance.
Collapse
Affiliation(s)
- V. Kumar
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
| | - I. Kymissis
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
| |
Collapse
|