Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing

We investigated the effects of chip size and N-polar n-GaN surface roughening on the performance of conventional thin-film blue-light micro-light-emitting diodes (TFFC μLEDs) and As+ ion isolated TFFC blue μLEDs. For this, TFFC μLEDs with two different sizes of 10 × 10 μm2 and 25 × 25 μm2 pixel arra...

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Main Authors: Tsung-Chih Wan, Ping-Hsun Tsai, Hao-Wu Lin, Chien-Chung Lin, Dong-Sing Wuu, Hiroshi Amano, Tae-Yeon Seong, Ray-Hua Horng
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Applied Surface Science Advances
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666523925000844
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author Tsung-Chih Wan
Ping-Hsun Tsai
Hao-Wu Lin
Chien-Chung Lin
Dong-Sing Wuu
Hiroshi Amano
Tae-Yeon Seong
Ray-Hua Horng
author_facet Tsung-Chih Wan
Ping-Hsun Tsai
Hao-Wu Lin
Chien-Chung Lin
Dong-Sing Wuu
Hiroshi Amano
Tae-Yeon Seong
Ray-Hua Horng
author_sort Tsung-Chih Wan
collection DOAJ
description We investigated the effects of chip size and N-polar n-GaN surface roughening on the performance of conventional thin-film blue-light micro-light-emitting diodes (TFFC μLEDs) and As+ ion isolated TFFC blue μLEDs. For this, TFFC μLEDs with two different sizes of 10 × 10 μm2 and 25 × 25 μm2 pixel array were fabricated. In all samples, N-face n-GaN surfaces were etched using a 4 M KOH solution after laser lift-off (LLO) process. A 2 min-etching resulted in the formation of pyramids (size: ∼90 – ∼270 nm), while the 4 min-etching produces pyramids (∼370 – ∼780 nm). Regardless of treatments, all samples exhibit similar forward bias characteristics. For all samples, the light output power increased after n-GaN surface roughening. Before the LLO process, the 10 μm-μLEDs showed higher EQE than the other samples with the implanted μLEDs showing the lowest EQE. All samples exhibited their highest EQE after optimal 4-min etching. Unlike before LLO, after 4 min-etching, the 10 μm- and 25 μm-μLEDs show almost similar EQEs, while the implanted μLEDs reveal a slightly lower EQE than the mesa μLEDs, but produce up to 74 % EQE improvement. Furthermore, the 10 μm-μLEDs showed the shortest photoluminescence (PL) decay, while the 25 μm-μLEDs gave the longest PL decay. The 10 μm μLEDs showed the highest ideality factor and the As+ ion-implanted μLEDs gave the lowest value. Based on time resolved PL and ideality factor, the size and etching time dependence of the EQE characteristics of all samples are described and discussed.
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publishDate 2025-06-01
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spelling doaj-art-4ca49d1b5707412fa6c36d10e453afd92025-08-20T03:26:38ZengElsevierApplied Surface Science Advances2666-52392025-06-012710077610.1016/j.apsadv.2025.100776Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processingTsung-Chih Wan0Ping-Hsun Tsai1Hao-Wu Lin2Chien-Chung Lin3Dong-Sing Wuu4Hiroshi Amano5Tae-Yeon Seong6Ray-Hua Horng7Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, ROC, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanGraduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, TaiwanDepartment of Applied Materials and Optoelectronic Engineering, National Chi Nan University, Nantou 54561, TaiwanInstitute of Materials and Systems for Sustainability, Nagoya University, 464-8601 Nagoya, JapanDepartment of Materials Science and Engineering, Korea University, Seoul 02841, South Korea; Corresponding author.Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, ROC, Taiwan; Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden; Corresponding author at: Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, ROC, Taiwan.We investigated the effects of chip size and N-polar n-GaN surface roughening on the performance of conventional thin-film blue-light micro-light-emitting diodes (TFFC μLEDs) and As+ ion isolated TFFC blue μLEDs. For this, TFFC μLEDs with two different sizes of 10 × 10 μm2 and 25 × 25 μm2 pixel array were fabricated. In all samples, N-face n-GaN surfaces were etched using a 4 M KOH solution after laser lift-off (LLO) process. A 2 min-etching resulted in the formation of pyramids (size: ∼90 – ∼270 nm), while the 4 min-etching produces pyramids (∼370 – ∼780 nm). Regardless of treatments, all samples exhibit similar forward bias characteristics. For all samples, the light output power increased after n-GaN surface roughening. Before the LLO process, the 10 μm-μLEDs showed higher EQE than the other samples with the implanted μLEDs showing the lowest EQE. All samples exhibited their highest EQE after optimal 4-min etching. Unlike before LLO, after 4 min-etching, the 10 μm- and 25 μm-μLEDs show almost similar EQEs, while the implanted μLEDs reveal a slightly lower EQE than the mesa μLEDs, but produce up to 74 % EQE improvement. Furthermore, the 10 μm-μLEDs showed the shortest photoluminescence (PL) decay, while the 25 μm-μLEDs gave the longest PL decay. The 10 μm μLEDs showed the highest ideality factor and the As+ ion-implanted μLEDs gave the lowest value. Based on time resolved PL and ideality factor, the size and etching time dependence of the EQE characteristics of all samples are described and discussed.http://www.sciencedirect.com/science/article/pii/S2666523925000844N-polar n-GaNThin-film blue-light micro-light-emitting diodesLaser lift-offEQEPL
spellingShingle Tsung-Chih Wan
Ping-Hsun Tsai
Hao-Wu Lin
Chien-Chung Lin
Dong-Sing Wuu
Hiroshi Amano
Tae-Yeon Seong
Ray-Hua Horng
Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing
Applied Surface Science Advances
N-polar n-GaN
Thin-film blue-light micro-light-emitting diodes
Laser lift-off
EQE
PL
title Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing
title_full Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing
title_fullStr Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing
title_full_unstemmed Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing
title_short Comparison of chip size effects of thin film GaN-based μLEDs fabricated by plasma etching and ion implantation processing
title_sort comparison of chip size effects of thin film gan based μleds fabricated by plasma etching and ion implantation processing
topic N-polar n-GaN
Thin-film blue-light micro-light-emitting diodes
Laser lift-off
EQE
PL
url http://www.sciencedirect.com/science/article/pii/S2666523925000844
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