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State-of-the-Art Nanophotonics Materials and Devices in China
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State-of-the-Art Nanophotonics Materials and Devices in China

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanophotonics Materials and Devices".

Deadline for manuscript submissions: closed (28 February 2022) | Viewed by 47496

Special Issue Editor

Prof. Dr. Weida Hu

grade E-Mail Website
Guest Editor
State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China
Interests: infrared photodetectors; infrared photodiodes; infrared phototransistors

Special Issue Information

Dear Colleagues,

Nanophotonics is a new interdisciplinary subject combining nanoscience and photonics. This Special Issue will be an overview of the research progress in nanophotonic materials and devices in China. Potential topics include, but are not limited to:

  • The applications of nanophotonics devices in photodetectors, including photoelectric detection, memory and integrated circuits;
  • Application of nanomaterials in solar cells;
  • Optical microstructures based on nanophotonics, including plasmon, metamaterials, and hypersurfaces;
  • Nanocomposites;
  • Physical properties, growth, and characterization of nanophotonics materials;
  • Applications of nanophotonics materials in light emitting devices, including small lasers;
  • Application of nanophotonics in biotechnology and medicine;
  • Other applications of nano optoelectronics materials and devices in optics, optoelectronics, and microelectronics.

The only limitation is that the main part of the study has to have been carried out in China or by Chinese researchers.

Prof. Dr. Weida Hu
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • photoelectric detection
  • laser
  • solar cell
  • plasma photonics
  • metamaterials and hypersurfaces
  • photonic crystal
  • luminescent materials

Published Papers (19 papers)

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Research

9 pages, 1828 KiB  
Article
Single-Walled Carbon Nanotube-Germanium Heterojunction for High-Performance Near-Infrared Photodetector
by Tao Qi, Yaolun Yu, Yanyan Hu, Kangjie Li, Nan Guo and Yi Jia
Nanomaterials 2022, 12(8), 1258; https://doi.org/10.3390/nano12081258 - 8 Apr 2022
Cited by 5 | Viewed by 1842
Abstract
In this research, we report on a high-performance near-infrared (near-IR) photodetector based on single-walled carbon nanotube-germanium (SWCNT-Ge) heterojunction by assembling SWCNT films onto n-type Ge substrate with ozone treatment. The ozone doping enhances the conductivity of carbon nanotube films and the formed interfacial [...] Read more.
In this research, we report on a high-performance near-infrared (near-IR) photodetector based on single-walled carbon nanotube-germanium (SWCNT-Ge) heterojunction by assembling SWCNT films onto n-type Ge substrate with ozone treatment. The ozone doping enhances the conductivity of carbon nanotube films and the formed interfacial oxide layer (GeOx) suppresses the leakage current and carriers’ recombination. The responsivity and detectivity in the near-IR region are estimated to be 362 mA W−1 and 7.22 × 1011 cm Hz1/2 W−1, respectively, which are three times the value of the untreated device. Moreover, a rapid response time of ~11 μs is obtained simultaneously. These results suggest that the simple SWCNT-Ge structure and ozone treatment method might be utilized to fabricate high-performance and low-cost near-IR photodetectors. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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12 pages, 5056 KiB  
Article
High Curie Temperature Achieved in the Ferromagnetic MnxGe1−x/Si Quantum Dots Grown by Ion Beam Co-Sputtering
by Xiaoxiao Duan, Shuming Ye, Jing Yang, Chen Li, Chunjiang Lu, Xinpeng He, Luran Zhang, Rongfei Wang, Feng Qiu, Jie Yang, Haoyang Cui and Chong Wang
Nanomaterials 2022, 12(4), 716; https://doi.org/10.3390/nano12040716 - 21 Feb 2022
Cited by 3 | Viewed by 1730
Abstract
Ferromagnetic semiconductors (FMSs) exhibit great potential in spintronic applications. It is believed that a revolution of microelectronic techniques can take off, once the challenges of FMSs in both the room-temperature stability of the ferromagnetic phase and the compatibility with Si-based technology are overcome. [...] Read more.
Ferromagnetic semiconductors (FMSs) exhibit great potential in spintronic applications. It is believed that a revolution of microelectronic techniques can take off, once the challenges of FMSs in both the room-temperature stability of the ferromagnetic phase and the compatibility with Si-based technology are overcome. In this article, the MnxGe1−x/Si quantum dots (QDs) with the Curie temperature (TC) higher than the room temperature were grown by ion beam co-sputtering (IBCS). With the Mn doping level increasing, the ripening growth of MnGe QDs occurs due to self-assembly via the Stranski–Krastanov (SK) growth mode. The surface-enhanced Raman scattering effect of Mn sites observed in MnGe QDs are used to reveal the distribution behavior of Mn atoms in QDs and the Si buffer layer. The Curie temperature of MnxGe1−x QDs increases, then slightly decreases with increasing the Mn doping level, and reaches its maximum value of 321 K at the doping level of 0.068. After a low-temperature and short-time annealing, the TC value of Mn0.068Ge0.932 QDs increases from 321 K to 383 K. The higher Ge composition and residual strain in the IBCS grown MnxGe1−x QDs are proposed to be responsible for maintaining the ferromagnetic phase above room temperature. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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7 pages, 1967 KiB  
Article
On the Near-Pole Hole Insertion Layer and the Far-Pole Hole Insertion Layer for Multi-Quantum-Well Deep Ultraviolet Light-Emitting Diodes
by Guanting Fang, Min Zhang and Dayuan Xiong
Nanomaterials 2022, 12(4), 629; https://doi.org/10.3390/nano12040629 - 14 Feb 2022
Cited by 4 | Viewed by 1667
Abstract
A novel Multi-Quantum-Well Deep Ultra Violet Light Emitting Diode (DUV-LED) device with a near-pole hole insertion layer and far-pole hole insertion layer was proposed and carefully studied. It was found that remarkable enhancements both in the light output power (LOP) and the internal [...] Read more.
A novel Multi-Quantum-Well Deep Ultra Violet Light Emitting Diode (DUV-LED) device with a near-pole hole insertion layer and far-pole hole insertion layer was proposed and carefully studied. It was found that remarkable enhancements both in the light output power (LOP) and the internal quantum efficiency (IQE) could be realized by using the far-electrode hole insertion layer and near-electrode hole insertion layer compared to the conventional DUV-LED device. Inserting the near-polar hole insertion layer can increase the electric field in the hole injection layer, which will promote the ionization of the acceptor, increase the hole concentration, and enhance the light-emitting performance of the device. In addition, inserting the far-pole hole insertion layer can suppress electron leakage and promote the hole injection. At the same time, the updated electron barrier height of P-AlGaN/GaN will indirectly weaken the electrostatic field in the hole injection layer, which remains inconducive to the ionization of the acceptor, implying that the electrostatic field between the P-AGaN/GaN layer can optimize the efficiency droop of the device. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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16 pages, 2363 KiB  
Article
Tunable Lifetime and Nonlinearity in Two Dimensional Materials Plasmonic-Photonic Absorber
by Renlong Zhou, Sa Yang and Yongming Zhao
Nanomaterials 2022, 12(3), 416; https://doi.org/10.3390/nano12030416 - 27 Jan 2022
Viewed by 1496
Abstract
We investigate a framework of local field, quality factor and lifetime for tunable graphene nanoribbon plasmonic-photonic absorbers and study the second order and third order nonlinear optical response of surface plasmons. The energy exchange of plasmonic-photonic absorber occurs in two main ways: one [...] Read more.
We investigate a framework of local field, quality factor and lifetime for tunable graphene nanoribbon plasmonic-photonic absorbers and study the second order and third order nonlinear optical response of surface plasmons. The energy exchange of plasmonic-photonic absorber occurs in two main ways: one way is the decay process of intrinsic loss for each resonant mode and another is the decay process of energy loss between graphene surface plasmon (GSP) mode and the external light field. The quality factor and lifetime of the plasmonic-photonic absorber can be obtained with using the coupled mode theory (CMT) and finite difference time domain (FDTD) method, which are effectively tunable with changing Fermi energy, carrier mobility and superstrate refractive index. The evolutions of total energy and lifetime of GSP are also shown, which are helpful for the study of micro processes in a two-dimensional material plasmonic-photonic absorber. The strongly localized fundamental field induces a desired increase of second harmonic (SH) wave and third harmonic (TH) wave. The manipulation of the quality factor and lifetime of the GSP makes graphene an excellent platform for tunable two-dimensional material plasmonic-photonic devices to realize the active control of the photoelectric/photothermal energy conversion process and higher harmonic generation. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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8 pages, 1998 KiB  
Article
GaN-Based Resonant-Cavity Light-Emitting Diodes Grown on Si
by Wen Chen, Meixin Feng, Yongjun Tang, Jian Wang, Jianxun Liu, Qian Sun, Xumin Gao, Yongjin Wang and Hui Yang
Nanomaterials 2022, 12(1), 134; https://doi.org/10.3390/nano12010134 - 31 Dec 2021
Cited by 3 | Viewed by 2220
Abstract
GaN-on-Si resonant-cavity light-emitting diodes (RCLEDs) have been successfully fabricated through wafer bonding and Si substrate removal. By combining the chemical mechanical polishing technique, we obtained a roughness of about 0.24 nm for a scan area of 5 μm × 5 μm. The double-sided [...] Read more.
GaN-on-Si resonant-cavity light-emitting diodes (RCLEDs) have been successfully fabricated through wafer bonding and Si substrate removal. By combining the chemical mechanical polishing technique, we obtained a roughness of about 0.24 nm for a scan area of 5 μm × 5 μm. The double-sided dielectric distributed Bragg reflectors could form a high-quality optical resonant cavity, and the cavity modes exhibited a linewidth of 1 nm at the peak wavelength of around 405 nm, corresponding to a quality factor of 405. High data transmission in free space with an opening in the eye diagram was exhibited at 150 Mbps, which is limited by the detection system. These results showed that GaN-based RCLEDs grown on Si are promising as a low-cost emitter for visible light communications in future. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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8 pages, 11091 KiB  
Article
Narrow-Linewidth GaN-on-Si Laser Diode with Slot Gratings
by Yongjun Tang, Meixin Feng, Jianxun Liu, Shizhao Fan, Xiujian Sun, Qian Sun, Shuming Zhang, Tong Liu, Yaping Kong, Zengli Huang, Masao Ikeda and Hui Yang
Nanomaterials 2021, 11(11), 3092; https://doi.org/10.3390/nano11113092 - 16 Nov 2021
Cited by 3 | Viewed by 2490
Abstract
This letter reports room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diodes. Unlike conventional distributed Bragg feedback laser diodes with hundreds of gratings, we employed only a few precisely defined slot gratings to narrow the linewidth and mitigate the negative effects of grating fabrication on [...] Read more.
This letter reports room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diodes. Unlike conventional distributed Bragg feedback laser diodes with hundreds of gratings, we employed only a few precisely defined slot gratings to narrow the linewidth and mitigate the negative effects of grating fabrication on the device performance. The slot gratings were incorporated into the ridge of conventional Fabry-Pérot cavity laser diodes. A subsequent wet etching in a tetramethyl ammonium hydroxide solution not only effectively removed the damages induced by the dry etching, but also converted the rough and tilted slot sidewalls into smooth and vertical ones. As a result, the threshold current was reduced by over 20%, and the reverse leakage current was decreased by over three orders of magnitude. Therefore, the room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diode has been successfully demonstrated. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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15 pages, 9102 KiB  
Article
Design and Numerical Analysis of an Infrared Cassegrain Telescope Based on Reflective Metasurfaces
by Song Yue, Zhe Zhang, Kunpeng Zhang, Huifang Guo, Ran Wang, Tonghui Dou, Dongliang Zhang, Lianqing Zhu, Haining Yang and Zichen Zhang
Nanomaterials 2021, 11(11), 2904; https://doi.org/10.3390/nano11112904 - 29 Oct 2021
Cited by 1 | Viewed by 2271
Abstract
Reflective imaging systems such as Cassegrain-type telescopes are widely utilized in astronomical observations. However, curved mirrors in traditional Cassegrain telescopes unavoidably make the imaging system bulky and costly. Recent developments in the field of metasurfaces provide an alternative way to construct optical systems, [...] Read more.
Reflective imaging systems such as Cassegrain-type telescopes are widely utilized in astronomical observations. However, curved mirrors in traditional Cassegrain telescopes unavoidably make the imaging system bulky and costly. Recent developments in the field of metasurfaces provide an alternative way to construct optical systems, possessing the potential to make the whole system flat, compact and lightweight. In this work, we propose a design for a miniaturized Cassegrain telescope by replacing the curved primary and secondary mirrors with flat and ultrathin metasurfaces. The meta-atoms, consisting of SiO2 stripes on an Al film, provide high reflectance (>95%) and a complete phase coverage of 0~2π at the operational wavelength of 4 μm. The optical functionality of the metasurface Cassegrain telescope built with these meta-atoms was confirmed and studied with numerical simulations. Moreover, fabrication errors were mimicked by introducing random width errors to each meta-atom; their influence on the optical performance of the metasurface device was studied numerically. The concept of the metasurface Cassegrain telescope operating in the infrared wavelength range can be extended to terahertz (THz), microwave and even radio frequencies for real-world applications, where metasurfaces with a large aperture size are more easily obtained. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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10 pages, 3104 KiB  
Article
Stacked Dual-Band Quantum Well Infrared Photodetector Based on Double-Layer Gold Disk Enhanced Local Light Field
by Chang Liu, Xuan Zuo, Shaohui Xu, Lianwei Wang and Dayuan Xiong
Nanomaterials 2021, 11(10), 2695; https://doi.org/10.3390/nano11102695 - 13 Oct 2021
Cited by 3 | Viewed by 1760
Abstract
We propose a stacked dual-band quantum well infrared photodetector (QWIP) integrated with a double-layer gold disk. Two 10-period quantum wells (QW) operating at different wavelengths are stacked together, and gold nano-disks are integrated on their respective surfaces. Numerical calculations by finite difference time [...] Read more.
We propose a stacked dual-band quantum well infrared photodetector (QWIP) integrated with a double-layer gold disk. Two 10-period quantum wells (QW) operating at different wavelengths are stacked together, and gold nano-disks are integrated on their respective surfaces. Numerical calculations by finite difference time domain (FDTD) showed that the best enhancement can be achieved at 13.2 and 11.0 µm. By integrating two metal disks, two plasmon microcavity structures can be formed with the substrate to excite localized surface plasmons (LSP) so that the vertically incident infrared light can be converted into electric field components perpendicular to the growth direction of the quantum well (EZ). The EZ electric field component can be enhanced up to 20 times compared to the incident light, and it is four times that of the traditional two-dimensional hole array (2DHA) grating. We calculated the enhancement factor and coupling efficiency of the device in the active region of the quantum well. The enhancement factor of the active region of the quantum well on the top layer remains above 25 at the wavelength of 13.2 μm, and the enhancement factor can reach a maximum of 45. Under this condition, the coupling efficiency of the device reaches 2800%. At the wavelength of 11.0 μm, the enhancement factor of the active region of the quantum well at the bottom is maintained above 6, and the maximum can reach about 16, and the coupling efficiency of the device reaches 800%. We also optimized the structural parameters and explored the influence of structural changes on the coupling efficiency. When the radius (r1, r2) of the two metal disks increases, the maximum coupling efficiency will be red-shifted as the wavelength increases. The double-layer gold disk structure we designed greatly enhances the infrared coupling of the two quantum well layers working at different wavelengths in the dual-band quantum well infrared photodetector. The structure we designed can be used in stacked dual-band quantum well infrared photodetectors, and the active regions of quantum wells working at two wavelengths can enhance the photoelectric coupling, and the enhancement effect is significant. Compared with the traditional optical coupling structure, the structure we proposed is simpler in process and has a more significant enhancement effect, which can meet the requirements of working in complex environments such as firefighting, night vision, and medical treatment. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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8 pages, 3549 KiB  
Article
Modulation of Ferroelectric and Optical Properties of La/Co-Doped KNbO3 Ceramics
by Xue Zhang, Ruijuan Qi, Shangwei Dong, Shuai Yang, Chengbin Jing, Lin Sun, Ye Chen, Xuekun Hong, Pingxiong Yang, Fangyu Yue and Junhao Chu
Nanomaterials 2021, 11(9), 2273; https://doi.org/10.3390/nano11092273 - 1 Sep 2021
Cited by 3 | Viewed by 2197
Abstract
The phase transition, microscopic morphology and optical and ferroelectric properties are studied in a series of La- and Co-doped KNbO3-based ceramics. The results show that the doping induces the transformation from the orthorhombic to the cubic phase of KNbO3, [...] Read more.
The phase transition, microscopic morphology and optical and ferroelectric properties are studied in a series of La- and Co-doped KNbO3-based ceramics. The results show that the doping induces the transformation from the orthorhombic to the cubic phase of KNbO3, significantly reduces the optical bandgap and simultaneously evidently improves the leakage, with a slight weakening of ferroelectric polarization. Further analysis reveals that (i) the Co doping is responsible for the obvious reduction of the bandgap, whereas it is reversed for the La doping; (ii) the slight deterioration of ferroelectricity is due to the doping-induced remarkable extrinsic defect levels and intrinsic oxygen vacancies; and (iii) the La doping can optimize the defect levels and inhibit the leakage. This investigation should both provide novel insight for exploring the bandgap engineering and ferroelectric properties of KNbO3, and suggest its potential applications, e.g., photovoltaic and multifunctional materials. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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10 pages, 1860 KiB  
Article
Enhancement of Energy-Storage Density in PZT/PZO-Based Multilayer Ferroelectric Thin Films
by Jie Zhang, Yuanyuan Zhang, Qianqian Chen, Xuefeng Chen, Genshui Wang, Xianlin Dong, Jing Yang, Wei Bai and Xiaodong Tang
Nanomaterials 2021, 11(8), 2141; https://doi.org/10.3390/nano11082141 - 22 Aug 2021
Cited by 22 | Viewed by 3416
Abstract
PbZr0.35Ti0.65O3 (PZT), PbZrO3 (PZO), and PZT/PZO ferroelectric/antiferroelectric multilayer films were prepared on a Pt/Ti/SiO2/Si substrate using the sol–gel method. Microstructures and physical properties such as the polarization behaviors, leakage current, dielectric features, and energy-storage characteristics [...] Read more.
PbZr0.35Ti0.65O3 (PZT), PbZrO3 (PZO), and PZT/PZO ferroelectric/antiferroelectric multilayer films were prepared on a Pt/Ti/SiO2/Si substrate using the sol–gel method. Microstructures and physical properties such as the polarization behaviors, leakage current, dielectric features, and energy-storage characteristics of the three films were systematically explored. All electric field-dependent phase transitions, from sharp to diffused, can be tuned by layer structure, indicated by the polarization, shift current, and dielectric properties. The leakage current behaviors suggested that the layer structure could modulate the current mechanism, including space-charge-limited bulk conduction for single layer films and Schottky emission for multilayer thin films. The electric breakdown strength of a PZT/PZO multilayer structure can be further enhanced to 1760 kV/cm, which is higher than PZT (1162 kV/cm) and PZO (1373 kV/cm) films. A recoverable energy-storage density of 21.1 J/cm3 was received in PZT/PZO multilayers due to its high electric breakdown strength. Our results demonstrate that a multilayer structure is an effective method for enhancing energy-storage capacitors. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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8 pages, 2159 KiB  
Article
Advantages of InGaN–GaN–InGaN Delta Barriers for InGaN-Based Laser Diodes
by Liwen Cheng, Zhenwei Li, Jiayi Zhang, Xingyu Lin, Da Yang, Haitao Chen, Shudong Wu and Shun Yao
Nanomaterials 2021, 11(8), 2070; https://doi.org/10.3390/nano11082070 - 15 Aug 2021
Cited by 6 | Viewed by 2222
Abstract
An InGaN laser diode with InGaN–GaN–InGaN delta barriers was designed and investigated numerically. The laser power–current–voltage performance curves, carrier concentrations, current distributions, energy band structures, and non-radiative and stimulated recombination rates in the quantum wells were characterized. The simulations indicate that an InGaN [...] Read more.
An InGaN laser diode with InGaN–GaN–InGaN delta barriers was designed and investigated numerically. The laser power–current–voltage performance curves, carrier concentrations, current distributions, energy band structures, and non-radiative and stimulated recombination rates in the quantum wells were characterized. The simulations indicate that an InGaN laser diode with InGaN–GaN–InGaN delta barriers has a lower turn-on current, a higher laser power, and a higher slope efficiency than those with InGaN or conventional GaN barriers. These improvements originate from modified energy bands of the laser diodes with InGaN–GaN–InGaN delta barriers, which can suppress electron leakage out of, and enhance hole injection into, the active region. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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11 pages, 2818 KiB  
Article
Improvement in the Output Power of Near-Ultraviolet LEDs of p-GaN Nanorods through SiO2 Nanosphere Mask Lithography with the Dip-Coating Method
by Wenkai Yue, Peixian Li, Xiaowei Zhou, Yanli Wang, Jinxing Wu and Junchun Bai
Nanomaterials 2021, 11(8), 2009; https://doi.org/10.3390/nano11082009 - 5 Aug 2021
Cited by 1 | Viewed by 1892
Abstract
In this paper, the conditions of the dip-coating method of SiO2 nanospheres are optimized, and a neatly arranged single-layer SiO2 array is obtained. On this basis, a “top-down” inductively coupled plasma (ICP) technique is used to etch the p-GaN layer to [...] Read more.
In this paper, the conditions of the dip-coating method of SiO2 nanospheres are optimized, and a neatly arranged single-layer SiO2 array is obtained. On this basis, a “top-down” inductively coupled plasma (ICP) technique is used to etch the p-GaN layer to prepare a periodic triangular nanopore array. After the etching is completed, the compressive stress in the epitaxial wafer sample is released to a certain extent. Then, die processing is performed on the etched LED epitaxial wafer samples. The LED chip with an etching depth of 150 nm has the highest overall luminous efficiency. Under a 100 mA injection current, the light output power (LOP) of the etched 150 nm sample is 23.61% higher than that of the original unetched sample. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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12 pages, 3123 KiB  
Article
High Q-Factor Hybrid Metamaterial Waveguide Multi-Fano Resonance Sensor in the Visible Wavelength Range
by Hongyan Yang, Yupeng Chen, Mengyin Liu, Gongli Xiao, Yunhan Luo, Houquan Liu, Jianqing Li and Libo Yuan
Nanomaterials 2021, 11(6), 1583; https://doi.org/10.3390/nano11061583 - 16 Jun 2021
Cited by 16 | Viewed by 3456
Abstract
We propose a high quality-factor (Q-factor) multi-Fano resonance hybrid metamaterial waveguide (HMW) sensor. By ingeniously designing a metal/dielectric hybrid waveguide structure, we can effectively tailor multi-Fano resonance peaks’ reflectance spectrum appearing in the visible wavelength range. In order to balance the high Q-factor [...] Read more.
We propose a high quality-factor (Q-factor) multi-Fano resonance hybrid metamaterial waveguide (HMW) sensor. By ingeniously designing a metal/dielectric hybrid waveguide structure, we can effectively tailor multi-Fano resonance peaks’ reflectance spectrum appearing in the visible wavelength range. In order to balance the high Q-factor and the best Fano resonance modulation depth, numerical calculation results demonstrated that the ultra-narrow linewidth resolution, the single-side quality factor, and Figure of Merit (FOM) can reach 1.7 nm, 690, and 236, respectively. Compared with the reported high Q-value (483) in the near-infrared band, an increase of 30% is achieved. Our proposed design may extend the application of Fano resonance in HMW from mid-infrared, terahertz band to visible band and have important research value in the fields of multi-wavelength non-labeled biosensing and slow light devices. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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12 pages, 5001 KiB  
Article
Design of Polarization-Independent Reflective Metalens in the Ultraviolet–Visible Wavelength Region
by Huifang Guo, Song Yue, Ran Wang, Yu Hou, Man Li, Kunpeng Zhang and Zichen Zhang
Nanomaterials 2021, 11(5), 1243; https://doi.org/10.3390/nano11051243 - 8 May 2021
Cited by 14 | Viewed by 4389
Abstract
Flat lens or metalens, as one of the most important application branches of metasurfaces, has recently been attracting significant research interest. Various reflective and transmissive metalenses have been demonstrated in the terathertz, infrared and visible wavelength range. However, metalens operating in the ultraviolet [...] Read more.
Flat lens or metalens, as one of the most important application branches of metasurfaces, has recently been attracting significant research interest. Various reflective and transmissive metalenses have been demonstrated in the terathertz, infrared and visible wavelength range. However, metalens operating in the ultraviolet (UV) wavelength range is rare. Moreover, the development of reflective UV metalens, the important counterpart of transmissive ones, falls far behind. In this work, with thorough investigation of material properties, we propose a reflective metalens based on silicon dioxide (SiO2) and aluminum (Al) that operates in the vacuum ultraviolet (VUV) to visible wavelength region. Four reflective metalenses were designed and optimized for wavelengths of 193, 441, 532 and 633 nm, and prominent focusing capability was observed, especially for the VUV wavelength of 193 nm. Dispersion characteristics of the metalenses were also studied within ±50 nm of the design wavelength, and negative dispersion was found for all cases. In addition, the SiO2 + Al platform can be, in principle, extended to the mid-infrared (IR) wavelength range. The reflective VUV metalens proposed in this work is expected to propel miniaturization and integration of UV optics. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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13 pages, 4065 KiB  
Article
Synthesis, Electronic Structure, and Electrochemical Properties of the Cubic Mg2MnO4 Spinel with Porous-Spongy Structure
by Zhenyan Wang, He Zhu, Li Ai, Jimin Ding, Pengfei Zhu, Ziqing Li, Bo Li, Hechun Jiang, Fapeng Yu, Xiulan Duan and Huaidong Jiang
Nanomaterials 2021, 11(5), 1122; https://doi.org/10.3390/nano11051122 - 27 Apr 2021
Cited by 11 | Viewed by 2485
Abstract
Mg2MnO4 nanoparticles with cubic spinel structure were synthesized by the sol-gel method using polyvinyl alcohol (PVA) as a chelating agent. X-ray powder diffraction, infrared spectrum (IR), scanning electron microscope (SEM), and transmission electron microscope (TEM) were used to characterize the [...] Read more.
Mg2MnO4 nanoparticles with cubic spinel structure were synthesized by the sol-gel method using polyvinyl alcohol (PVA) as a chelating agent. X-ray powder diffraction, infrared spectrum (IR), scanning electron microscope (SEM), and transmission electron microscope (TEM) were used to characterize the crystalline phase and particle size of as-synthesized nanoparticles. The electronic structure of Mg2MnO4 spinel was studied by X-ray photoelectron spectroscopy (XPS). The results showed that pure cubic Mg2MnO4 spinel nanoparticles were obtained when the annealing temperature was 500–700 °C. The samples had a porous-spongy structure assembled by nanoparticles. XPS studies indicated that Mg2MnO4 nanoparticles were mixed spinel structures and the degree of cation inversion decreased with increasing annealing temperature. Furthermore, the performance of Mg2MnO4 as lithium anode material was studied. The results showed that Mg2MnO4 samples had good cycle stability except for the slight decay in the capacity at 50 cycles. The coulombic efficiency (ratio of discharge and charge capacity) in most cycles was near 100%. The sample annealed at 600 °C exhibited good electrochemical properties, the first discharge capacity was 771.5 mAh/g, and the capacity remained 340 mAh/g after 100 cycles. The effect of calcination temperature on the charge–discharge performance of the samples was studied and discussed. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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7 pages, 2233 KiB  
Article
Dielectric Relaxation Behavior of BTO/LSMO Heterojunction
by Guoqiang Song, Yuanyuan Zhang, Sheng Li, Jing Yang, Wei Bai and Xiaodong Tang
Nanomaterials 2021, 11(5), 1109; https://doi.org/10.3390/nano11051109 - 25 Apr 2021
Cited by 7 | Viewed by 2412
Abstract
The BaTiO3 (BTO)/La0.7Sr0.3MnO3 (LSMO) magnetoelectric composite films were prepared by sol-gel method on STO (001) substrates. The heterojunction has highly preferred orientation and exhibits well ferroelectric properties with perfect hysteresis loops and microscopic polarization switch behaviors. The [...] Read more.
The BaTiO3 (BTO)/La0.7Sr0.3MnO3 (LSMO) magnetoelectric composite films were prepared by sol-gel method on STO (001) substrates. The heterojunction has highly preferred orientation and exhibits well ferroelectric properties with perfect hysteresis loops and microscopic polarization switch behaviors. The most interesting thing is the abnormal dielectric relaxation phenomenon in the dielectric spectra at high frequency range and around the phase transition temperature of LSMO. By analyzing the resistance properties of LSMO films, it is indicated that charge-based interfacial coupling, Maxwell-Wagner effect due to the JT polaron and fast resistivity rise in LSMO layer is the main reason. This work emphasizes the crucial role of resistivity exchanges and of carrier accumulation at interfaces for the application of magnetoelectric heterojunction. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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8 pages, 1699 KiB  
Article
Design of Multifunctional Janus Metasurface Based on Subwavelength Grating
by Ruonan Ji, Chuan Jin, Kun Song, Shao-Wei Wang and Xiaopeng Zhao
Nanomaterials 2021, 11(4), 1034; https://doi.org/10.3390/nano11041034 - 19 Apr 2021
Cited by 16 | Viewed by 2884
Abstract
In this paper, a Janus metasurface is designed by breaking the structural symmetry based on the polarization selection property of subwavelength grating. The structure comprises three layers: a top layer having a metallic nanostructure, a dielectric spacer, and a bottom layer having subwavelength [...] Read more.
In this paper, a Janus metasurface is designed by breaking the structural symmetry based on the polarization selection property of subwavelength grating. The structure comprises three layers: a top layer having a metallic nanostructure, a dielectric spacer, and a bottom layer having subwavelength grating. For a forward incidence, the metal-insulator-metal (MIM) structure operates as a gap plasmonic cavity if the linearly polarized (LP) component is parallel to the grating wires. It also acts as a high-efficiency dual-layer grating polarizer for the orthogonal LP component. For the backward incidence, the high reflectance of the grating blocks the function of the gap plasmonic cavity, leading to its pure functioning as a polarizer. A bifunctional Janus metasurface for 45 degrees beam deflector and polarizer, with a transmission of 0.87 and extinction ratio of 3840, is designed at 1.55 μm and is investigated to prove the validity of the proposed strategy. Moreover, the proposed metasurface can be cascaded to achieve more flexible functions since these functions are independent in terms of operational mechanism and structural parameters. A trifunctional Janus metasurface that acts as a focusing lens, as a reflector, and as a polarizer is designed based on this strategy. The proposed metasurface and the design strategy provide convenience and flexibility in the design of multifunctional, miniaturized, and integrated optical components for polarization-related analysis and for detection systems. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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10 pages, 2885 KiB  
Article
Atomic Insights into Ti Doping on the Stability Enhancement of Truncated Octahedron LiMn2O4 Nanoparticles
by Wangqiong Xu, Hongkai Li, Yonghui Zheng, Weibin Lei, Zhenguo Wang, Yan Cheng, Ruijuan Qi, Hui Peng, Hechun Lin, Fangyu Yue and Rong Huang
Nanomaterials 2021, 11(2), 508; https://doi.org/10.3390/nano11020508 - 17 Feb 2021
Cited by 20 | Viewed by 2787
Abstract
Ti-doped truncated octahedron LiTixMn2-xO4 nanocomposites were synthesized through a facile hydrothermal treatment and calcination process. By using spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), the effects of Ti-doping on the structure evolution and stability enhancement of LiMn [...] Read more.
Ti-doped truncated octahedron LiTixMn2-xO4 nanocomposites were synthesized through a facile hydrothermal treatment and calcination process. By using spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), the effects of Ti-doping on the structure evolution and stability enhancement of LiMn2O4 are revealed. It is found that truncated octahedrons are easily formed in Ti doping LiMn2O4 material. Structural characterizations reveal that most of the Ti4+ ions are composed into the spinel to form a more stable spinel LiTixMn2−xO4 phase framework in bulk. However, a portion of Ti4+ ions occupy 8a sites around the {001} plane surface to form a new TiMn2O4-like structure. The combination of LiTixMn2−xO4 frameworks in bulk and the TiMn2O4-like structure at the surface may enhance the stability of the spinel LiMn2O4. Our findings demonstrate the critical role of Ti doping in the surface chemical and structural evolution of LiMn2O4 and may guide the design principle for viable electrode materials. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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12 pages, 2201 KiB  
Article
Strong Terahertz Absorption of Monolayer Graphene Embedded into a Microcavity
by Xuguang Guo, Lejie Xue, Zhenxing Yang, Mengjian Xu, Yiming Zhu, Dixiang Shao, Zhanglong Fu, Zhiyong Tan, Chang Wang, Juncheng Cao and Chao Zhang
Nanomaterials 2021, 11(2), 421; https://doi.org/10.3390/nano11020421 - 7 Feb 2021
Cited by 3 | Viewed by 2187
Abstract
Terahertz reflection behaviors of metallic-grating-dielectric-metal (MGDM) microcavity with a monolayer graphene embedded into the dielectric layer are theoretically investigated. A tunable wideband reflection dip at about the Fabry–Pérot resonant frequency of the structure is found. The reflectance at the dip frequency can be [...] Read more.
Terahertz reflection behaviors of metallic-grating-dielectric-metal (MGDM) microcavity with a monolayer graphene embedded into the dielectric layer are theoretically investigated. A tunable wideband reflection dip at about the Fabry–Pérot resonant frequency of the structure is found. The reflectance at the dip frequency can be electrically tuned in the range of 96.5% and 8.8%. Because of the subwavelength distance between the metallic grating and the monolayer graphene, both of the evanescent grating slit waveguide modes and the evanescent Rayleigh modes play key roles in the strong absorption by the graphene layer. The dependence of reflection behaviors on the carrier scattering rate of graphene is analyzed. A prototype MGDM-graphene structure is fabricated to verify the theoretical analysis. Our investigations are helpful for the developments of electrically controlled terahertz modulators, switches, and reconfigurable antennas based on the MGDM-graphene structures. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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