Nanostructured Light-Emitters, Volume II

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "A:Physics".

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 10059

Special Issue Editor


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Guest Editor
Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA
Interests: nanostructures; epitaxial growth; nanophotonics; light-emitting diodes; laser diodes; solid-state lighting; micro-displays
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Special Issue Information

Dear Colleagues,

Significant progress has been made in nanophotonics and the use of nanostructured materials for optoelectronic devices, including light-emitting diodes (LEDs) and laser diodes, which have recently attracted considerable attention due to their unique geometry. Nanostructures in small dimensions, comprising nanowires, nanotubes, and nanoparticles, etc., can be perfectly integrated into a variety of technological platforms, offering novel physical, and chemical properties for high-performance, light-emitting devices.

The exploitation of new nanostructures for light-emitting devices and their optical/electrical properties is necessary for their emerging practical device applications. For instance, III-nitride nanowires offer several distinct advantages including being nearly-free of dislocations and a polarization field, which results in the enhanced efficiency and output power of LEDs with an emission wavelength that varies from deep ultraviolet to near-infrared. Two-dimensional nanomaterials, as well as nanoplasmonics, can be used efficiently to enhance light absorption and emission in optoelectronics devices.

This Special Issue will present the most recent advances in the field of nanophotonics, which focuses on LEDs and laser diodes. We invite contributions of original research articles, as well as review articles that are aligned to the following topics that include, but are not limited to, the theoretical calculation, synthesis, characterization, and application of such novel nanostructures for light-emitting devices. The application of nanostructured light-emitters in general lighting, imaging, and displays is also highly encouraged.

Dr. Hieu Pham Trung Nguyen
Guest Editor

Manuscript Submission Information

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Keywords

  • Nanostructured photonics
  • Nanophotonics
  • Low-dimensional semiconductors
  • Light-emitting diodes
  • Laser diodes

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Published Papers (5 papers)

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Research

6 pages, 2059 KiB  
Article
Enhanced Red Emission from Amorphous Silicon Carbide Films via Nitrogen Doping
by Guangxu Chen, Sibin Chen, Zewen Lin, Rui Huang and Yanqing Guo
Micromachines 2022, 13(12), 2043; https://doi.org/10.3390/mi13122043 - 22 Nov 2022
Cited by 2 | Viewed by 1046
Abstract
The enhanced red photoluminescence (PL) from Si-rich amorphous silicon carbide (a-SiCx) films was analyzed in this study using nitrogen doping. The increase in nitrogen doping concentration in films results in the significant enhancement of PL intensity by more than three times. [...] Read more.
The enhanced red photoluminescence (PL) from Si-rich amorphous silicon carbide (a-SiCx) films was analyzed in this study using nitrogen doping. The increase in nitrogen doping concentration in films results in the significant enhancement of PL intensity by more than three times. The structure and bonding configuration of films were investigated using Raman and Fourier transform infrared absorption spectroscopies, respectively. The PL and analysis results of bonding configurations of films suggested that the enhancement of red PL is mainly caused by the reduction in nonradiative recombination centers as a result of the weak Si–Si bonds substituted by Si–N bonds. Full article
(This article belongs to the Special Issue Nanostructured Light-Emitters, Volume II)
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9 pages, 6186 KiB  
Article
Improving Color Quality of Nanowire White Light-Emitting Diodes with Mn4+ Doped Fluoride Nanosheets
by Thi Hong Quan Vu, Thi Tuyet Doan, Barsha Jain, Ravi Teja Velpula, Tung Cao Thanh Pham, Hieu Pham Trung Nguyen and Hoang-Duy Nguyen
Micromachines 2021, 12(8), 965; https://doi.org/10.3390/mi12080965 - 15 Aug 2021
Cited by 6 | Viewed by 1899
Abstract
A two-dimensional nanostructured fluoride red-emitting phosphor with an excellent quantum yield of ~91% is studied for cost-effective and high-color quality nanowire white light-emitting diodes (WLEDs). K2TiF6:Mn4+ phosphors are synthesized via an emulsification method using surfactants as sodium dodecyl [...] Read more.
A two-dimensional nanostructured fluoride red-emitting phosphor with an excellent quantum yield of ~91% is studied for cost-effective and high-color quality nanowire white light-emitting diodes (WLEDs). K2TiF6:Mn4+ phosphors are synthesized via an emulsification method using surfactants as sodium dodecyl sulphonate and oleic acid. The K2TiF6:Mn4+ phosphors in ultra-thin and nanosheet crystals are observed via scanning electron microscopy and high-resolution transmission electron microscopy. The surfactants are found to play a key role in inhibition of KTFM crystal growth process and stabilization of Mn4+ ions doping into the K2TiF6 host. The prepared phosphors exhibited intensive red emission at approximately 632 nm and excellent thermal stability in the range of 300–500 K upon 460 nm light excitation. Moreover, the K2TiF6:Mn4+ nanosheets were integrated on InGaN/AlGaN nanowire WLEDs for color quality study. The results show that the nanowire WLEDs with red-emitting phosphor exhibit unprecedentedly high color rendering index ~96.4, and correlated color temperature ~4450 K. Full article
(This article belongs to the Special Issue Nanostructured Light-Emitters, Volume II)
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8 pages, 2372 KiB  
Article
The Effect of Nitrogen Incorporation on the Optical Properties of Si-Rich a-SiCx Films Deposited by VHF PECVD
by Hongliang Li, Zewen Lin, Yanqing Guo, Jie Song, Rui Huang and Zhenxu Lin
Micromachines 2021, 12(6), 637; https://doi.org/10.3390/mi12060637 - 30 May 2021
Cited by 1 | Viewed by 1980
Abstract
The influence of N incorporation on the optical properties of Si-rich a-SiCx films deposited by very high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD) was investigated. The increase in N content in the films was found to cause a remarkable enhancement in photoluminescence [...] Read more.
The influence of N incorporation on the optical properties of Si-rich a-SiCx films deposited by very high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD) was investigated. The increase in N content in the films was found to cause a remarkable enhancement in photoluminescence (PL). Relative to the sample without N incorporation, the sample incorporated with 33% N showed a 22-fold improvement in PL. As the N content increased, the PL band gradually blueshifted from the near-infrared to the blue region, and the optical bandgap increased from 2.3 eV to 5.0 eV. The enhancement of PL was suggested mainly from the effective passivation of N to the nonradiative recombination centers in the samples. Given the strong PL and wide bandgap of the N incorporated samples, they were used to further design an anti-counterfeiting label. Full article
(This article belongs to the Special Issue Nanostructured Light-Emitters, Volume II)
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7 pages, 2448 KiB  
Article
Effect of Thermal Annealing on the Photoluminescence of Dense Si Nanodots Embedded in Amorphous Silicon Nitride Films
by Qianqian Liu, Xiaoxuan Chen, Hongliang Li, Yanqing Guo, Jie Song, Wenxing Zhang, Chao Song, Rui Huang and Zewen Lin
Micromachines 2021, 12(4), 354; https://doi.org/10.3390/mi12040354 - 25 Mar 2021
Cited by 1 | Viewed by 1879
Abstract
Luminescent amorphous silicon nitride-containing dense Si nanodots were prepared by using very-high-frequency plasma-enhanced chemical vapor deposition at 250 °C. The influence of thermal annealing on photoluminescence (PL) was studied. Compared with the pristine film, thermal annealing at 1000 °C gave rise to a [...] Read more.
Luminescent amorphous silicon nitride-containing dense Si nanodots were prepared by using very-high-frequency plasma-enhanced chemical vapor deposition at 250 °C. The influence of thermal annealing on photoluminescence (PL) was studied. Compared with the pristine film, thermal annealing at 1000 °C gave rise to a significant enhancement by more than twofold in terms of PL intensity. The PL featured a nanosecond recombination dynamic. The PL peak position was independent of the excitation wavelength and measured temperatures. By combining the Raman spectra and infrared absorption spectra analyses, the enhanced PL was suggested to be from the increased density of radiative centers related to the Si dangling bonds (K0) and N4+ or N20 as a result of bonding configuration reconstruction. Full article
(This article belongs to the Special Issue Nanostructured Light-Emitters, Volume II)
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11 pages, 3846 KiB  
Article
Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
by Barsha Jain, Ravi Teja Velpula, Moulik Patel, Sharif Md. Sadaf and Hieu Pham Trung Nguyen
Micromachines 2021, 12(3), 334; https://doi.org/10.3390/mi12030334 - 21 Mar 2021
Cited by 4 | Viewed by 2563
Abstract
To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type AlxGa(1−x)N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, [...] Read more.
To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type AlxGa(1−x)N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, holes are depleted in the EBL due to the formation of positive sheet polarization charges at the heterointerface of the last quantum barrier (QB)/EBL. Subsequently, the hole injection efficiency of the LED is severely limited. In this regard, we propose an EBL-free AlGaN deep UV LED structure using graded staircase quantum barriers (GSQBs) instead of conventional QBs without affecting the hole injection efficiency. The reported structure exhibits significantly reduced thermal velocity and mean free path of electrons in the active region, thus greatly confines the electrons over there and tremendously decreases the electron leakage into the p-region. Moreover, such specially designed QBs reduce the quantum-confined Stark effect in the active region, thereby improves the electron and hole wavefunctions overlap. As a result, both the internal quantum efficiency and output power of the GSQB structure are ~2.13 times higher than the conventional structure at 60 mA. Importantly, our proposed structure exhibits only ~20.68% efficiency droop during 0–60 mA injection current, which is significantly lower compared to the regular structure. Full article
(This article belongs to the Special Issue Nanostructured Light-Emitters, Volume II)
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