240 nm AlGaN-based micro-LEDs with different sizes are designed and fabricated.Then,the external quantum efficiency(EQE)and light extraction efficiency(LEE)are systematically investigated by comparing size and edge ef...240 nm AlGaN-based micro-LEDs with different sizes are designed and fabricated.Then,the external quantum efficiency(EQE)and light extraction efficiency(LEE)are systematically investigated by comparing size and edge effects.Here,it is revealed that the peak optical output power increases by 81.83%with the size shrinking from 50.0 to 25.0μm.Thereinto,the LEE increases by 26.21%and the LEE enhancement mainly comes from the sidewall light extraction.Most notably,transversemagnetic(TM)mode light intensifies faster as the size shrinks due to the tilted mesa side-wall and Al reflector design.However,when it turns to 12.5μm sized micro-LEDs,the output power is lower than 25.0μm sized ones.The underlying mechanism is that even though protected by SiO2 passivation,the edge effect which leads to current leakage and Shockley-Read-Hall(SRH)recombination deteriorates rapidly with the size further shrinking.Moreover,the ratio of the p-contact area to mesa area is much lower,which deteriorates the p-type current spreading at the mesa edge.These findings show a role of thumb for the design of high efficiency micro-LEDs with wavelength below 250 nm,which will pave the way for wide applications of deep ultraviolet(DUV)micro-LEDs.展开更多
Hybrid white micro-pillar structure light emitting diodes(LEDs)have been manufacture utilizing blue micro-LEDs arrays integrated with 580 nm CIS((CuInS2-ZnS)/ZnS)core/shell quantum dots.The fabricated hybrid white mic...Hybrid white micro-pillar structure light emitting diodes(LEDs)have been manufacture utilizing blue micro-LEDs arrays integrated with 580 nm CIS((CuInS2-ZnS)/ZnS)core/shell quantum dots.The fabricated hybrid white micro-LEDs have good electrical properties,which are manifested in relatively low turn-on voltage and reverse leakage current.High-quality hybrid white light emission has been demonstrated by the hybrid white micro-LEDs after a systemic optimization,in which the corresponding color coordinates are calculated to be(0.3303,0.3501)and the calculated color temperature is 5596 K.This result indicates an effective way to achieve high-performance white LEDs and shows great promise in a large range of applications in the future including micro-displays,bioinstrumentation and visible light communication.展开更多
Due to the excellent optoelectronic properties,fast response time,outstanding power efficiency and high stability,micro-LED plays an increasingly important role in the new generation of display technology compared wit...Due to the excellent optoelectronic properties,fast response time,outstanding power efficiency and high stability,micro-LED plays an increasingly important role in the new generation of display technology compared with LCD and OLED display.This paper mainly introduces the preparation methods of the GaN-based micro-LED array,the optoelectronic characteristics,and several key technologies to achieve full-color display,such as transfer printing,color conversion by quantum dot and local strain engineering.展开更多
There is a significantly increasing demand of developing augmented reality and virtual reality(AR and VR) devices,where micro-LEDs(μLEDs) with a dimension of ≤ 5 μm are the key elements. Typically, μLEDs are fabri...There is a significantly increasing demand of developing augmented reality and virtual reality(AR and VR) devices,where micro-LEDs(μLEDs) with a dimension of ≤ 5 μm are the key elements. Typically, μLEDs are fabricated by dry-etching technologies, unavoidably leading to a severe degradation in optical performance as a result of dry-etching induced damages. This becomes a particularly severe issue when the dimension of LEDs is ≤ 10 μm. In order to address the fundamental challenge, the Sheffield team has proposed and then developed a direct epitaxial approach to achievingμLEDs, where the dry-etching technologies for the formation of μLED mesas are not needed anymore. This paper provides a review on this technology and then demonstrates a number of monolithically integrated devices on a single chip using this technology.展开更多
Micro-light-emitting diode[micro-LED]has been widely concerned in the field of display and wireless optical communication due to its excellent optoelectronic characteristics,but the reduction of the pixel size has a s...Micro-light-emitting diode[micro-LED]has been widely concerned in the field of display and wireless optical communication due to its excellent optoelectronic characteristics,but the reduction of the pixel size has a significant impact on the performance of GaN-based micro-LEDs,which then affects the display and wireless optical communication applications.In this work,different sizes of violet and blue GaN-based micro-LEDs have been successfully fabricated,and the size-dependent characteristics of micro-LEDs in display and communication applications have been systematically studied.It can be found that the pixel size reduction of the micro-LEDs from 80 to 10μm leads to an obvious decrease in light output power[LOP]by88.30% and 44.10% for blue and violet micro-LEDs,respectively,and a decrease in peak external quantum efficiency[EQE]by55.14% and 46.25%for blue and violet micro-LEDs,respectively.Additionally,micro-LEDs with smaller sizes tend to exhibit a less obvious shift of peak wavelength and smaller broadening of full-width at half-maximum[FWHM]with the increases of current density,showing the potential to achieve a stable display with high quality.Also,the influence of current density on chrominance coordinate migration is determined,which shows that the driving current density corresponding to the maximum EQE can promote display efficiency and color gamut.In addition,the violet and blue micro-LEDs with a diameter of 20μm show potential in balancing between the LOP and the modulation bandwidth to achieve the highest data rates of 1.347 and 1.032 Gbps,respectively,in wireless optical communication applications.The results of this study are of great significance for optimizing the pixel size of the micro-LED to improve the performance in display and wireless optical communication applications in the future.展开更多
Super-fine electrohydrodynamic inkjet(SIJ)printing of perovskite nanocrystal(PNC)colloid ink exhibits significant potential in the fabrication of high-resolution color conversion microstructures arrays for fullcolor m...Super-fine electrohydrodynamic inkjet(SIJ)printing of perovskite nanocrystal(PNC)colloid ink exhibits significant potential in the fabrication of high-resolution color conversion microstructures arrays for fullcolor micro-LED displays.However,the impact of solvent on both the printing process and the morphology of SIJ-printed PNC color conversion microstructures remains underexplored.In this study,we prepared samples of CsPbBr3PNC colloid inks in various solvents and investigated the solvent's impact on SIJ printed PNC microstructures.Our findings reveal that the boiling point of the solvent is crucial to the SIJ printing process of PNC colloid inks.Only does the boiling point of the solvent fall in the optimal range,the regular positioned,micron-scaled,conical PNC microstructures can be successfully printed.Below this optimal range,the ink is unable to be ejected from the nozzle;while above this range,irregular positioned microstructures with nanoscale height and coffee-ring-like morphology are produced.Based on these observations,high-resolution color conversion PNC microstructures were effectively prepared using SIJ printing of PNC colloid ink dispersed in dimethylbenzene solvent.展开更多
The low modulation bandwidth of deep-ultraviolet(UV) light sources is considered as the main reason limiting the data transmission rate of deep-UV communications. Here, we present high-bandwidth Ⅲ-nitride microlight-...The low modulation bandwidth of deep-ultraviolet(UV) light sources is considered as the main reason limiting the data transmission rate of deep-UV communications. Here, we present high-bandwidth Ⅲ-nitride microlight-emitting diodes(μLEDs) emitting in the UV-C region and their applications in deep-UV communication systems. The fabricated UV-C μLEDs with 566 μm2 emission area produce an optical power of 196 μW at the 3400 A∕cm2 current density. The measured 3 dB modulation bandwidth of these μLEDs initially increases linearly with the driving current density and then saturates as 438 MHz at a current density of 71 A∕cm2, which is limited by the cutoff frequency of the commercial avalanche photodiode used for the measurement. A deep-UV communication system is further demonstrated. By using the UV-C μLED, up to 800 Mbps and 1.1 Gbps data transmission rates at bit error ratio of 3.8 × 10-3 are achieved assuming on-off keying and orthogonal frequency-division multiplexing modulation schemes, respectively.展开更多
基金This work was supported by National Key R&D Program of China(2022YFB3605103)the National Natural Science Foundation of China(62204241,U22A2084,62121005,and 61827813)+3 种基金the Natural Science Foundation of Jilin Province(20230101345JC,20230101360JC,and 20230101107JC)the Youth Innovation Promotion Association of CAS(2023223)the Young Elite Scientist Sponsorship Program By CAST(YESS20200182)the CAS Talents Program(E30122E4M0).
文摘240 nm AlGaN-based micro-LEDs with different sizes are designed and fabricated.Then,the external quantum efficiency(EQE)and light extraction efficiency(LEE)are systematically investigated by comparing size and edge effects.Here,it is revealed that the peak optical output power increases by 81.83%with the size shrinking from 50.0 to 25.0μm.Thereinto,the LEE increases by 26.21%and the LEE enhancement mainly comes from the sidewall light extraction.Most notably,transversemagnetic(TM)mode light intensifies faster as the size shrinks due to the tilted mesa side-wall and Al reflector design.However,when it turns to 12.5μm sized micro-LEDs,the output power is lower than 25.0μm sized ones.The underlying mechanism is that even though protected by SiO2 passivation,the edge effect which leads to current leakage and Shockley-Read-Hall(SRH)recombination deteriorates rapidly with the size further shrinking.Moreover,the ratio of the p-contact area to mesa area is much lower,which deteriorates the p-type current spreading at the mesa edge.These findings show a role of thumb for the design of high efficiency micro-LEDs with wavelength below 250 nm,which will pave the way for wide applications of deep ultraviolet(DUV)micro-LEDs.
基金supported by National Key R&D Program of China (2016YFB0400100)National Nature Science Foundation of China (61921005, 61674076, 61674081, 61605071, 61974062)+5 种基金Nature Science Foundation of Jiangsu Province (BY2013077, BK20141320, BE2015111)Six Talent Peaks Project of Jiangsu Province (XYDXX-081)Open Fund of the State Key Laboratory on Integrated Optoelectronics (IOSKL2017KF03)Innovation Project of Postgraduate Training in Jiangsu Province (KYCX18_0031)Fundamental Research Funds for the Central Universities (021014380096)Collaborative Innovation Center of Solid State Lighting and Energy-saving Electronics
文摘Hybrid white micro-pillar structure light emitting diodes(LEDs)have been manufacture utilizing blue micro-LEDs arrays integrated with 580 nm CIS((CuInS2-ZnS)/ZnS)core/shell quantum dots.The fabricated hybrid white micro-LEDs have good electrical properties,which are manifested in relatively low turn-on voltage and reverse leakage current.High-quality hybrid white light emission has been demonstrated by the hybrid white micro-LEDs after a systemic optimization,in which the corresponding color coordinates are calculated to be(0.3303,0.3501)and the calculated color temperature is 5596 K.This result indicates an effective way to achieve high-performance white LEDs and shows great promise in a large range of applications in the future including micro-displays,bioinstrumentation and visible light communication.
基金National Natural Science Foundation of China(NSFC)(61974031,61705041 and 61571135)Shanghai Sailing Program(17YF1429100)+2 种基金Shanghai Technical Standard Program(18DZ2206000)State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Funding(SKLIPR1607)National Key Research and Development Program of China(2017YFB0403603).
文摘Due to the excellent optoelectronic properties,fast response time,outstanding power efficiency and high stability,micro-LED plays an increasingly important role in the new generation of display technology compared with LCD and OLED display.This paper mainly introduces the preparation methods of the GaN-based micro-LED array,the optoelectronic characteristics,and several key technologies to achieve full-color display,such as transfer printing,color conversion by quantum dot and local strain engineering.
基金Project supported by the Engineering and Physical Sciences Research Council (EPSRC),U.K.,via EP/P006973/1,EP/T013001/1,and EP/M015181/1。
文摘There is a significantly increasing demand of developing augmented reality and virtual reality(AR and VR) devices,where micro-LEDs(μLEDs) with a dimension of ≤ 5 μm are the key elements. Typically, μLEDs are fabricated by dry-etching technologies, unavoidably leading to a severe degradation in optical performance as a result of dry-etching induced damages. This becomes a particularly severe issue when the dimension of LEDs is ≤ 10 μm. In order to address the fundamental challenge, the Sheffield team has proposed and then developed a direct epitaxial approach to achievingμLEDs, where the dry-etching technologies for the formation of μLED mesas are not needed anymore. This paper provides a review on this technology and then demonstrates a number of monolithically integrated devices on a single chip using this technology.
基金supported by the National Key R&D Program of China(No.2023YFB3610500)the National Natural Science Foundation of China(Nos.62204128 and 62404112)+3 种基金the Natural Science Foundation of Jiangsu Province(Nos.BK20220399 and BK20243037)the Foundation of Jiangsu Provincial Double-Innovation Doctor Program(No.JSSCBS20210522)the Industry-University Collaborative Project(Nos.2022out212,2024out026,and 2024out254)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Nos.NY224098 and NY223158)。
文摘Micro-light-emitting diode[micro-LED]has been widely concerned in the field of display and wireless optical communication due to its excellent optoelectronic characteristics,but the reduction of the pixel size has a significant impact on the performance of GaN-based micro-LEDs,which then affects the display and wireless optical communication applications.In this work,different sizes of violet and blue GaN-based micro-LEDs have been successfully fabricated,and the size-dependent characteristics of micro-LEDs in display and communication applications have been systematically studied.It can be found that the pixel size reduction of the micro-LEDs from 80 to 10μm leads to an obvious decrease in light output power[LOP]by88.30% and 44.10% for blue and violet micro-LEDs,respectively,and a decrease in peak external quantum efficiency[EQE]by55.14% and 46.25%for blue and violet micro-LEDs,respectively.Additionally,micro-LEDs with smaller sizes tend to exhibit a less obvious shift of peak wavelength and smaller broadening of full-width at half-maximum[FWHM]with the increases of current density,showing the potential to achieve a stable display with high quality.Also,the influence of current density on chrominance coordinate migration is determined,which shows that the driving current density corresponding to the maximum EQE can promote display efficiency and color gamut.In addition,the violet and blue micro-LEDs with a diameter of 20μm show potential in balancing between the LOP and the modulation bandwidth to achieve the highest data rates of 1.347 and 1.032 Gbps,respectively,in wireless optical communication applications.The results of this study are of great significance for optimizing the pixel size of the micro-LED to improve the performance in display and wireless optical communication applications in the future.
基金supported by the National Natural Science Foundation of China(No.62374142)Fundamental Research Funds for the Central Universities(Nos.20720220085 and 20720240064)+2 种基金External Cooperation Program of Fujian(No.2022I0004)Major Science and Technology Project of Xiamen in China(No.3502Z20191015)Xiamen Natural Science Foundation Youth Project(No.3502Z202471002)。
文摘Super-fine electrohydrodynamic inkjet(SIJ)printing of perovskite nanocrystal(PNC)colloid ink exhibits significant potential in the fabrication of high-resolution color conversion microstructures arrays for fullcolor micro-LED displays.However,the impact of solvent on both the printing process and the morphology of SIJ-printed PNC color conversion microstructures remains underexplored.In this study,we prepared samples of CsPbBr3PNC colloid inks in various solvents and investigated the solvent's impact on SIJ printed PNC microstructures.Our findings reveal that the boiling point of the solvent is crucial to the SIJ printing process of PNC colloid inks.Only does the boiling point of the solvent fall in the optimal range,the regular positioned,micron-scaled,conical PNC microstructures can be successfully printed.Below this optimal range,the ink is unable to be ejected from the nozzle;while above this range,irregular positioned microstructures with nanoscale height and coffee-ring-like morphology are produced.Based on these observations,high-resolution color conversion PNC microstructures were effectively prepared using SIJ printing of PNC colloid ink dispersed in dimethylbenzene solvent.
基金Engineering and Physical Sciences Research Council(EPSRC)(EP/M01326X/1)
文摘The low modulation bandwidth of deep-ultraviolet(UV) light sources is considered as the main reason limiting the data transmission rate of deep-UV communications. Here, we present high-bandwidth Ⅲ-nitride microlight-emitting diodes(μLEDs) emitting in the UV-C region and their applications in deep-UV communication systems. The fabricated UV-C μLEDs with 566 μm2 emission area produce an optical power of 196 μW at the 3400 A∕cm2 current density. The measured 3 dB modulation bandwidth of these μLEDs initially increases linearly with the driving current density and then saturates as 438 MHz at a current density of 71 A∕cm2, which is limited by the cutoff frequency of the commercial avalanche photodiode used for the measurement. A deep-UV communication system is further demonstrated. By using the UV-C μLED, up to 800 Mbps and 1.1 Gbps data transmission rates at bit error ratio of 3.8 × 10-3 are achieved assuming on-off keying and orthogonal frequency-division multiplexing modulation schemes, respectively.
