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We investigate the mechanism of light extraction enhancement of a GaN-based light-emitting diode (LED) grown on patterned sapphire substrate (PSS), that has ZnO nanorod arrays (NRAs) fabricated on top of the device using the hydrothermal method. We found that the light output power of the LED with ZnO NRAs increases by approximately 30% compared to the conventional LED without damaging the electrical properties of the device. We argue that the gradual decrease of the effective refractive index, which is caused by the fabrication of ZnO NRAs, is the mechanism of the observed improvement. Our argument is confirmed by cross-sectional confocal scanning electroluminescence microscopy (CSEM) and the theoretical simulations, where we observed a distinct increase of the transmission at the interface between LED and air at the operation wavelength of the LED. In addition, the plane-view CSEM results indicate that ZnO NRAs, which were grown on the bare p-type GaN layer as an electrical safety margin area, also contribute to the enhanced light output power of the LED, which indicate further enhancement is manifested even in the optically ineffective sacrificial area.
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http://dx.doi.org/10.1039/c3nr06584g | DOI Listing |
Anal Chim Acta
June 2024
State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin, 300457, China; Key Laboratory of Food Quality and Health of Tianjin, Tianjin University of Science & Technology, 300457, Tianjin, China; Tianjin Key Laboratory of Food Science and Health, School
Background: Surface-enhanced Raman scattering (SERS) has gained widespread use in molecule-level detection benefiting from its high sensitivity, nondestructive data acquisition, and capacity for providing molecular fingerprint information. However, the strong adhesion of target molecules to the substrate (known as the "memory effect") inherently hinders the reusability of SERS substrates. Research has shown that self-cleaning SERS substrates based on versatile semiconductor materials with SERS enhancement capabilities and solar photocatalytic properties offer an effective platform for the sensitive detection and degradation of harmful molecules.
View Article and Find Full Text PDFNanoscale Adv
July 2023
Department of Materials Science and Engineering, Center Of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong Hong Kong SAR P. R. China +852-3442-7823.
ZnO nanorod arrays (NRAs) have potential applications as building blocks for nanoscale electronic, optoelectronic, and sensing applications. The density of ZnO NRAs is controlled by a simple low-cost hydrothermal growth process. It is shown that Ti and Au thin buffer layers can be used to control ZnO NRA density up to an order of magnitude on a wide variety of substrates including bare glass AZO, ZnO seeded AZO, FTO and ITO substrates, respectively.
View Article and Find Full Text PDFChemosphere
January 2022
Advanced Materials and Devices Laboratory (AMDL), Department of Nanoscience and Technology, Bharathiar University, Coimbatore, India. Electronic address:
The present investigation demonstrates an enhancement of the visible photocatalytic activities by C ion implantation in ZnO nanorod arrays (NRAs). Vertically aligned ZnO NRAs were prepared by seed layer assisted solution-phase growth and implanted with 70 keV carbon ions at various fluencies: 1E15, 5E15, 1E16, and 3E16 ions/cm. X-ray diffraction and FESEM results revealed the crystalline 1D ZnO NRAs having a length of ∼3 μm with a diameter in the range of 150-200 nm.
View Article and Find Full Text PDFACS Omega
June 2021
Department of Physics and Electronic Information Engineering, Minjiang University, Fuzhou 350108, P. R. China.
ZnO nanorod arrays (NRAs) were fabricated on polyester fabrics (PFs) by a two-step method and modified with Ag by magnetron sputtering. The photogenerated charge transport properties of the Ag/ZnO nanorod heterojunctions were studied by a self-made Kelvin probe system and a surface photovoltage (SPV) test system. The measured work functions (WFs) of the deposited Ag and ZnO nanorod are 4.
View Article and Find Full Text PDFJ Colloid Interface Sci
April 2021
National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Department of Micro/Nano Electronics, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China. Electronic address:
The photoelectrochemical (PEC) performance of ZnO is restricted by its low light absorption ability and high recombination rate of photogenerated carriers. In order to overcome these drawbacks, ZnO/CdS/CdSe heterostructures are prepared on Zn foil substrate using facile three-step methods containing hydrothermal growth, successive ionic layer adsorption reaction (SILAR) and modified chemical bath deposition (CBD). The effects of process parameters containing the number of SILAR cycles of CdS, sensitization sequence of CdS and CdSe, and precursors of CdSe on PEC performance of ZnO/CdS/CdSe heterostructures, and ZnO NRAs on PEC performance of CdS/CdSe co-sensitizer have been scrutinized.
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