Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs
Micro-size light-emitting diodes (μLEDs) are high-brightness, low-power optoelectronic devices with significant potential in display technology, lighting, and biomedical applications. AlGaInP-based red LEDs experience severe size-dependent effects when scaled to the micron level, and addressing the...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-03-01
|
| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/15/4/288 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850183335696924672 |
|---|---|
| author | Shuhan Zhang Yun Zhang Hongyu Qin Qian Fan Xianfeng Ni Li Tao Xing Gu |
| author_facet | Shuhan Zhang Yun Zhang Hongyu Qin Qian Fan Xianfeng Ni Li Tao Xing Gu |
| author_sort | Shuhan Zhang |
| collection | DOAJ |
| description | Micro-size light-emitting diodes (μLEDs) are high-brightness, low-power optoelectronic devices with significant potential in display technology, lighting, and biomedical applications. AlGaInP-based red LEDs experience severe size-dependent effects when scaled to the micron level, and addressing the fabrication challenges of GaN-based red μLED arrays is crucial for achieving homogeneous integration. This study investigates the employment of KOH wet treatments to alleviate efficiency degradation caused by sidewall leakage currents. GaN-based red μLED arrays with pixel sizes ranging from 5 × 5 µm<sup>2</sup> to 20 × 20 µm<sup>2</sup> were grown using metal-organic chemical vapor deposition (MOCVD), and then fabricated via rapid thermal annealing, mesa etching, sidewall wet treatment, electrode deposition, sidewall passivation, chemical-mechanical polishing, and via processes. The arrays, with pixel densities ranging from 668 PPI (Pixel Per Inch) to 1336 PPI, consist of 10,000 to 40,000 emitting pixels, and their optoelectronic properties were systematically evaluated. The arrays with varying pixel sizes fabricated in this study were subjected to three distinct processing conditions: without KOH treatment, 3 min of KOH treatment, and 5 min of KOH treatment. Electrical characterization reveals that the 5-min KOH treatment significantly reduces leakage current, enhancing the electrical performance, as compared to the samples without KOH treatment or 3-min treatment. In terms of optical properties, while the arrays without any KOH treatment failed to emit light, the ones with 3- and 5-min KOH treatment exhibit excellent optical uniformity and negligible blue shift. Most arrays treated for 5 min demonstrate superior light output power (LOP) and optoelectronic efficiency, with the 5 µm pixel arrays exhibiting unexpectedly high performance. The results suggest that extending the KOH wet treatment time effectively mitigates sidewall defects, reduces non-radiative recombination, and enhances surface roughness, thereby minimizing optical losses. These findings provide valuable insights for optimizing the fabrication of high-performance GaN-based red μLEDs and contribute to the development of stable, high-quality small-pixel μLEDs for advanced display and lighting applications. |
| format | Article |
| id | doaj-art-1623302ef6704ca290f180116b93ce21 |
| institution | OA Journals |
| issn | 2073-4352 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj-art-1623302ef6704ca290f180116b93ce212025-08-20T02:17:24ZengMDPI AGCrystals2073-43522025-03-0115428810.3390/cryst15040288Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDsShuhan Zhang0Yun Zhang1Hongyu Qin2Qian Fan3Xianfeng Ni4Li Tao5Xing Gu6Institute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaInstitute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaInstitute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaInstitute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaInstitute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaInstitute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaInstitute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, ChinaMicro-size light-emitting diodes (μLEDs) are high-brightness, low-power optoelectronic devices with significant potential in display technology, lighting, and biomedical applications. AlGaInP-based red LEDs experience severe size-dependent effects when scaled to the micron level, and addressing the fabrication challenges of GaN-based red μLED arrays is crucial for achieving homogeneous integration. This study investigates the employment of KOH wet treatments to alleviate efficiency degradation caused by sidewall leakage currents. GaN-based red μLED arrays with pixel sizes ranging from 5 × 5 µm<sup>2</sup> to 20 × 20 µm<sup>2</sup> were grown using metal-organic chemical vapor deposition (MOCVD), and then fabricated via rapid thermal annealing, mesa etching, sidewall wet treatment, electrode deposition, sidewall passivation, chemical-mechanical polishing, and via processes. The arrays, with pixel densities ranging from 668 PPI (Pixel Per Inch) to 1336 PPI, consist of 10,000 to 40,000 emitting pixels, and their optoelectronic properties were systematically evaluated. The arrays with varying pixel sizes fabricated in this study were subjected to three distinct processing conditions: without KOH treatment, 3 min of KOH treatment, and 5 min of KOH treatment. Electrical characterization reveals that the 5-min KOH treatment significantly reduces leakage current, enhancing the electrical performance, as compared to the samples without KOH treatment or 3-min treatment. In terms of optical properties, while the arrays without any KOH treatment failed to emit light, the ones with 3- and 5-min KOH treatment exhibit excellent optical uniformity and negligible blue shift. Most arrays treated for 5 min demonstrate superior light output power (LOP) and optoelectronic efficiency, with the 5 µm pixel arrays exhibiting unexpectedly high performance. The results suggest that extending the KOH wet treatment time effectively mitigates sidewall defects, reduces non-radiative recombination, and enhances surface roughness, thereby minimizing optical losses. These findings provide valuable insights for optimizing the fabrication of high-performance GaN-based red μLEDs and contribute to the development of stable, high-quality small-pixel μLEDs for advanced display and lighting applications.https://www.mdpi.com/2073-4352/15/4/288μLEDsKOH wet treatmentGaN |
| spellingShingle | Shuhan Zhang Yun Zhang Hongyu Qin Qian Fan Xianfeng Ni Li Tao Xing Gu Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs Crystals μLEDs KOH wet treatment GaN |
| title | Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs |
| title_full | Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs |
| title_fullStr | Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs |
| title_full_unstemmed | Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs |
| title_short | Impact of KOH Wet Treatment on the Electrical and Optical Characteristics of GaN-Based Red μLEDs |
| title_sort | impact of koh wet treatment on the electrical and optical characteristics of gan based red μleds |
| topic | μLEDs KOH wet treatment GaN |
| url | https://www.mdpi.com/2073-4352/15/4/288 |
| work_keys_str_mv | AT shuhanzhang impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds AT yunzhang impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds AT hongyuqin impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds AT qianfan impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds AT xianfengni impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds AT litao impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds AT xinggu impactofkohwettreatmentontheelectricalandopticalcharacteristicsofganbasedredmleds |