A low hole injection efficiency for InGaN/GaN micro-light-emitting diodes(μLEDs) has become one of the main bottlenecks affecting the improvement of the external quantum efficiency(EQE) and the optical power. In this...A low hole injection efficiency for InGaN/GaN micro-light-emitting diodes(μLEDs) has become one of the main bottlenecks affecting the improvement of the external quantum efficiency(EQE) and the optical power. In this work, we propose and fabricate a polarization mismatched p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure for 445 nm GaN-based μLEDs with the size of 40 × 40 μm^(2), which serves as the hole injection layer. The polarization-induced electric field in the p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure provides holes with more energy and can facilitate the non-equilibrium holes to transport into the active region for radiative recombination. Meanwhile, a secondary etched mesa for μLEDs is also designed, which can effectively keep the holes apart from the defected region of the mesa sidewalls, and the surface nonradiative recombination can be suppressed. Therefore, the proposed μLED with the secondary etched mesa and the p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure has the enhanced EQE and the improved optical power density when compared with the μLED without such designs.展开更多
A versatile nanosphere composite lithography（NSCL） combining both the advantages of multiple-exposure nanosphere lens lithography（MENSLL） and nanosphere template lithography（NSTL） is demonstrated. By well contro...A versatile nanosphere composite lithography（NSCL） combining both the advantages of multiple-exposure nanosphere lens lithography（MENSLL） and nanosphere template lithography（NSTL） is demonstrated. By well controlling the development, washing and the drying processes, the nanosphere monolayer can be well retained on the substrate after developing and washing. Thus the NSTL can be performed based on MENSLL to fabricate nanoring, nanocrescent and hierarchical multiple structures. The pattern size and the shape can be systemically tuned by shrinking nanospheres by using dry etching and adjusting the tilted angle. It is a natural nanopattern alignment process and possesses a great potential in the scope of nano-science due to its low cost,simplicity, and versatility for variuos nano-fabrications.展开更多
基金supported in part by the National Natural Science Foundation of China (Grant Nos.62074050 and 61975051)Research Fund by State Key Laboratory of Reliability and Intelligence of Electrical Equipment,Hebei University of Technology (Grant Nos.EERI PI2020008 and EERI_PD2021012)Joint Research Project for Tunghsu Group and Hebei University of Technology (Grant No.HI1909)。
文摘A low hole injection efficiency for InGaN/GaN micro-light-emitting diodes(μLEDs) has become one of the main bottlenecks affecting the improvement of the external quantum efficiency(EQE) and the optical power. In this work, we propose and fabricate a polarization mismatched p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure for 445 nm GaN-based μLEDs with the size of 40 × 40 μm^(2), which serves as the hole injection layer. The polarization-induced electric field in the p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure provides holes with more energy and can facilitate the non-equilibrium holes to transport into the active region for radiative recombination. Meanwhile, a secondary etched mesa for μLEDs is also designed, which can effectively keep the holes apart from the defected region of the mesa sidewalls, and the surface nonradiative recombination can be suppressed. Therefore, the proposed μLED with the secondary etched mesa and the p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure has the enhanced EQE and the improved optical power density when compared with the μLED without such designs.
基金supported by the National Natural Science Foundation of China(Nos.61604051,51502074 and61474109)the Natural Science of Foundation of Tianjin(Nos.16JCQNJC01000 and 16JCYBJC16200)+1 种基金the Technology Foundation for Selected Overseas Chinese Scholar by Ministry of Human Resources and Social Security of the People’s Republic of China(No.CG2016008001)the Research Award for Top Young Scientist of Excellence of Hebei Province(No.210013)
文摘A versatile nanosphere composite lithography（NSCL） combining both the advantages of multiple-exposure nanosphere lens lithography（MENSLL） and nanosphere template lithography（NSTL） is demonstrated. By well controlling the development, washing and the drying processes, the nanosphere monolayer can be well retained on the substrate after developing and washing. Thus the NSTL can be performed based on MENSLL to fabricate nanoring, nanocrescent and hierarchical multiple structures. The pattern size and the shape can be systemically tuned by shrinking nanospheres by using dry etching and adjusting the tilted angle. It is a natural nanopattern alignment process and possesses a great potential in the scope of nano-science due to its low cost,simplicity, and versatility for variuos nano-fabrications.
