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16 pages, 5352 KiB

Open AccessArticle

Studies of Electrical Parameters and Thermal Stability of HiPIMS Hafnium Oxynitride (HfO_xN_y) Thin Films

by Mirosław Puźniak, Wojciech Gajewski, Aleksandra Seweryn, Marcin T. Klepka, Bartłomiej S. Witkowski, Marek Godlewski and Robert Mroczyński

Materials 2023, 16(6), 2539; https://doi.org/10.3390/ma16062539 - 22 Mar 2023

Cited by 2 | Viewed by 1671

Abstract

This work demonstrated the optimization of HiPIMS reactive magnetron sputtering of hafnium oxynitride (HfO_xN_y) thin films. During the optimization procedure, employing Taguchi orthogonal tables, the parameters of examined dielectric films were explored, utilizing optical methods (spectroscopic ellipsometry and refractometry), [...] Read more.

This work demonstrated the optimization of HiPIMS reactive magnetron sputtering of hafnium oxynitride (HfO_xN_y) thin films. During the optimization procedure, employing Taguchi orthogonal tables, the parameters of examined dielectric films were explored, utilizing optical methods (spectroscopic ellipsometry and refractometry), electrical characterization (C-V, I-V measurements of MOS structures), and structural investigation (AFM, XRD, XPS). The thermal stability of fabricated HfO_xN_y layers, up to 800 °C, was also investigated. The presented results demonstrated the correctness of the optimization methodology. The results also demonstrated the significant stability of hafnia-based layers at up to 800 °C. No electrical parameters or surface morphology deteriorations were demonstrated. The structural analysis revealed comparable electrical properties and significantly greater immunity to high-temperature treatment in HfO_xN_y layers formed using HiPIMS, as compared to those formed using the standard pulsed magnetron sputtering technique. The results presented in this study confirmed that the investigated hafnium oxynitride films, fabricated through the HiPIMS process, could potentially be used as a thermally-stable gate dielectric in self-aligned MOS structures and devices. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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14 pages, 3894 KiB

Open AccessArticle

A Comparative Study of Eu³⁺-Doped Sillenites: Bi₁₂SiO₂₀ (BSO) and Bi₁₂GeO₂₀ (BGO)

by Marcin Kowalczyk, Marcin Kaczkan, Andrzej Majchrowski and Michał Malinowski

Materials 2023, 16(4), 1621; https://doi.org/10.3390/ma16041621 - 15 Feb 2023

Cited by 2 | Viewed by 1796

Abstract

The spectroscopic properties of Eu³⁺-doped Bi₁₂SiO₂₀ (BSO) were investigated and compared with that of Eu³⁺-doped Bi₁₂GeO₂₀ (BGO). The emission properties and the absorption spectra have been measured at 10 K as well as [...] Read more.

The spectroscopic properties of Eu³⁺-doped Bi₁₂SiO₂₀ (BSO) were investigated and compared with that of Eu³⁺-doped Bi₁₂GeO₂₀ (BGO). The emission properties and the absorption spectra have been measured at 10 K as well as at 300 K (room temperature). Luminescence was detected due to the direct excitation of the ⁵D₀ level of Eu³⁺, as well as through the excitation of the ⁵D₁ level. The Judd–Ofelt theoretical framework was used to compute the radiative lifetimes (τ) and the omega parameters (Ω_λ). The electric dipole transition probabilities, asymmetry ratios (R), along with the branching ratios (β) were also determined based on the obtained experimental data. The strongest detected luminescence belongs to the ⁵D₀ → ⁷F₀ transition observed at 578 nm, similar to the BGO sillenite. Reasons for the major presence of the ⁵D₀ → ⁷F₀ emission, theoretically forbidden by the Judd–Ofelt Theory, were investigated and compared with that of the BGO sillenite. Obtained results showed that the strong ⁵D₀ → ⁷F₀ line is also present in Eu:BSO, indicating that this is a feature of the entire sillenite family and not just Eu:BGO. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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18 pages, 7118 KiB

Open AccessArticle

Investigation of the Microstructure, Optical, Electrical and Nanomechanical Properties of ZnOx Thin Films Deposited by Magnetron Sputtering

by Michał Mazur, Agata Obstarczyk, Witold Posadowski, Jarosław Domaradzki, Szymon Kiełczawa, Artur Wiatrowski, Damian Wojcieszak, Małgorzata Kalisz, Marcin Grobelny and Jan Szmidt

Materials 2022, 15(19), 6551; https://doi.org/10.3390/ma15196551 - 21 Sep 2022

Cited by 8 | Viewed by 2075

Abstract

The paper presents the results of an investigation of the influence of technological parameters on the microstructure, optical, electrical and nanomechanical properties of zinc oxide coatings prepared using the pulsed reactive magnetron sputtering method. Three sets of ZnOx thin films were deposited in [...] Read more.

The paper presents the results of an investigation of the influence of technological parameters on the microstructure, optical, electrical and nanomechanical properties of zinc oxide coatings prepared using the pulsed reactive magnetron sputtering method. Three sets of ZnOx thin films were deposited in metallic, shallow dielectric and deep dielectric sputtering modes. Structural investigations showed that thin films deposited in the metallic mode were nanocrystalline with mixed hexagonal phases of metallic zinc and zinc oxide with crystallite size of 9.1 and 6.0 nm, respectively. On the contrary, the coatings deposited in both dielectric modes had a nanocrystalline ZnO structure with an average crystallite size smaller than 10 nm. Moreover, coatings deposited in the dielectric modes had an average transmission of 84% in the visible wavelength range, while thin films deposited in the metallic mode were opaque. Measurements of electrical properties revealed that the resistivity of as-deposited thin films was in the range of 10⁻⁴ Ωcm to 10⁸ Ωcm. Coatings deposited in the metallic mode had the lowest hardness of 2.2 GPa and the worst scratch resistance among all sputtered coatings, whereas the best mechanical properties were obtained for the film sputtered in the deep dielectric mode. The obtained hardness of 11.5 GPa is one of the highest reported to date in the literature for undoped ZnO. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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15 pages, 2603 KiB

Open AccessArticle

Nano-Ag Particles Embedded in C-Matrix: Preparation, Properties and Application in Cell Metabolism

by Sylwia Terpilowska, Stanislaw Gluszek, Elzbieta Czerwosz, Halina Wronka, Piotr Firek, Jan Szmidt, Malgorzata Suchanska, Justyna Keczkowska, Bozena Kaczmarska, Mirosław Kozlowski and Ryszard Diduszko

Materials 2022, 15(17), 5826; https://doi.org/10.3390/ma15175826 - 24 Aug 2022

Cited by 2 | Viewed by 1546

Abstract

The application of nano-Ag grains as antiviral and antibacterial materials is widely known since ancient times. The problem is the toxicity of the bulk or big-size grain materials. It is known that nano-sized silver grains affect human and animal cells in some medical [...] Read more.

The application of nano-Ag grains as antiviral and antibacterial materials is widely known since ancient times. The problem is the toxicity of the bulk or big-size grain materials. It is known that nano-sized silver grains affect human and animal cells in some medical treatments. The aim of this study is to investigate the influence of nano-Ag grains embedded in a carbonaceous matrix on cytotoxicity, genotoxicity in fibroblasts, and mutagenicity. The nanocomposite film is composed of silver nanograins embedded in a carbonaceous matrix and it was obtained via the PVD method by deposition from two separated sources of fullerenes and silver acetate powders. This method allows for the preparation of material in the form of a film or powder, in which Ag nanograins are stabilized by a carbon network. The structure and morphology of this material were studied using SEM/EDX, XRD, and Raman spectroscopy. The toxicology studies were performed for various types of the material differing in the size of Ag nanograins. Furthermore, it was found that these properties, such as cell viability, genotoxicity, and mutagenicity, depend on Ag grain size. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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13 pages, 13232 KiB

Open AccessArticle

Raytracing Modelling of Infrared Light Management Using Molybdenum Disulfide (MoS₂) as a Back-Reflector Layer in a Silicon Heterojunction Solar Cell (SHJ)

by Mohammed Islam Elsmani, Noshin Fatima, Ignacio Torres, Susana Fernández, Michael Paul A. Jallorina, Puvaneswaran Chelvanathan, Ahmad Rujhan Mohd Rais, Mohd Norizam Md Daud, Sharifah Nurain Syed Nasir, Suhaila Sepeai, Norasikin Ahmad Ludin, Mohd Asri Mat Teridi, Kamaruzzaman Sopian and Mohd Adib Ibrahim

Materials 2022, 15(14), 5024; https://doi.org/10.3390/ma15145024 - 19 Jul 2022

Cited by 2 | Viewed by 1998

Abstract

The silicon heterojunction solar cell (SHJ) is considered the dominant state-of-the-art silicon solar cell technology due to its excellent passivation quality and high efficiency. However, SHJ’s light management performance is limited by its narrow optical absorption in long-wave near-infrared (NIR) due to the [...] Read more.

The silicon heterojunction solar cell (SHJ) is considered the dominant state-of-the-art silicon solar cell technology due to its excellent passivation quality and high efficiency. However, SHJ’s light management performance is limited by its narrow optical absorption in long-wave near-infrared (NIR) due to the front, and back tin-doped indium oxide (ITO) layer’s free carrier absorption and reflection losses. Despite the light-trapping efficiency (LTE) schemes adopted by SHJ in terms of back surface texturing, the previous investigations highlighted the ITO layer as a reason for an essential long-wavelength light loss mechanism in SHJ solar cells. In this study, we propose the use of Molybdenum disulfide (MoS₂) as a way of improving back-reflection in SHJ. The text presents simulations of the optical response in the backside of the SHJ applying the Monte-Carlo raytracing method with a web-based Sunsolve high-precision raytracing tool. The solar cells’ electrical parameters were also resolved using the standard electrical equivalent circuit model provided by Sunsolve. The proposed structure geometry slightly improved the SHJ cell optical current density by ~0.37% (rel.), and hence efficiency (η) by about 0.4% (rel.). The SHJ cell efficiency improved by 21.68% after applying thinner back ITO of about 30 nm overlayed on ~1 nm MoS₂. The efficiency improvement following the application of MoS₂ is tentatively attributed to the increased NIR absorption in the silicon bulk due to the light constructive interface with the backside components, namely silver (Ag) and ITO. Study outcomes showed that improved SHJ efficiency could be further optimized by addressing front cell components, mainly front ITO and MoS₂ contact engineering. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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17 pages, 5566 KiB

Open AccessArticle

Spatial Dispersion in Hypercrystal Distributed Feedback Lasing

by Bartosz Janaszek and Paweł Szczepański

Materials 2022, 15(10), 3482; https://doi.org/10.3390/ma15103482 - 12 May 2022

Cited by 2 | Viewed by 1375

Abstract

This work is a first approach to investigate the role of spatial dispersion in photonic hypercrystals (PHCs). The scope of the presented analysis is focused on exploiting nonlocality, which can be controlled by appropriate design of the structure, to obtain new light generation [...] Read more.

This work is a first approach to investigate the role of spatial dispersion in photonic hypercrystals (PHCs). The scope of the presented analysis is focused on exploiting nonlocality, which can be controlled by appropriate design of the structure, to obtain new light generation effects in a distributed feedback (DFB) laser based on PHC, which are not observable under weak spatial dispersion. Here, we use effective medium approximation and our original model of threshold laser generation based on anisotropic transfer matrix method. To unequivocally identify nonlocal generation phenomena, the scope of our analysis includes comparison between local and nonlocal threshold generation spectra, which may be obtained for different geometries of PHC structure. In particular, we have presented that, in the presence of strong spatial dispersion, it is possible to obtain spectrally shifted Bragg wavelengths of TE- and TM-polarization spectra, lowered generation threshold levels for both light polarizations, generation of light of selected light polarization (TE or TM), or simultaneous generation of TE- and TM-polarized waves at different frequencies with controllable spectral separation, instead of single mode operation anticipated with local approach. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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9 pages, 1909 KiB

Open AccessArticle

Charge-Trapping-Induced Hysteresis Effects in Highly Doped Silicon Metal–Oxide–Semiconductor Structures

by Piotr Wiśniewski and Bogdan Majkusiak

Materials 2022, 15(8), 2733; https://doi.org/10.3390/ma15082733 - 8 Apr 2022

Cited by 2 | Viewed by 1990

Abstract

It is shown that a simple metal–oxide–semiconductor (MOS) structure with highly doped silicon substrate can exhibit current–voltage hysteresis effects related to sudden rises and drops in the flowing electric current. Experimental current–voltage characteristics of Al-SiO₂-(n++Si) structures are presented and discussed. Their [...] Read more.

It is shown that a simple metal–oxide–semiconductor (MOS) structure with highly doped silicon substrate can exhibit current–voltage hysteresis effects related to sudden rises and drops in the flowing electric current. Experimental current–voltage characteristics of Al-SiO₂-(n++Si) structures are presented and discussed. Their analysis shows that the ohmic and shallow traps assisted space-charge limited conduction (SCLC) are the dominating transport mechanisms. Sudden rises and drops in the flowing current, leading to the current–voltage hysteresis effects, are attributed to tunneling through deep traps in the oxide. Based on inelastic electron tunneling spectroscopy (IETS), the energy levels of the deep traps and their position in the oxide are evaluated. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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23 pages, 185666 KiB

Open AccessEditor’s ChoiceArticle

Passive Photonic Integrated Circuits Elements Fabricated on a Silicon Nitride Platform

by Marcin Lelit, Mateusz Słowikowski, Maciej Filipiak, Marcin Juchniewicz, Bartłomiej Stonio, Bartosz Michalak, Krystian Pavłov, Marcin Myśliwiec, Piotr Wiśniewski, Andrzej Kaźmierczak, Krzysztof Anders, Stanisław Stopiński, Romuald B. Beck and Ryszard Piramidowicz

Materials 2022, 15(4), 1398; https://doi.org/10.3390/ma15041398 - 14 Feb 2022

Cited by 13 | Viewed by 5293

Abstract

The fabrication processes for silicon nitride photonic integrated circuits evolved from microelectronics components technology—basic processes have common roots and can be executed using the same type of equipment. In comparison to that of electronics components, passive photonic structures require fewer manufacturing steps and [...] Read more.

The fabrication processes for silicon nitride photonic integrated circuits evolved from microelectronics components technology—basic processes have common roots and can be executed using the same type of equipment. In comparison to that of electronics components, passive photonic structures require fewer manufacturing steps and fabricated elements have larger critical dimensions. In this work, we present and discuss our first results on design and development of fundamental building blocks for silicon nitride integrated photonic platform. The scope of the work covers the full design and manufacturing chain, from numerical simulations of optical elements, design, and fabrication of the test structures to optical characterization and analysis the results. In particular, technological processes were developed and evaluated for fabrication of the waveguides (WGs), multimode interferometers (MMIs), and arrayed waveguide gratings (AWGs), which confirmed the potential of the technology and correctness of the proposed approach. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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16 pages, 7519 KiB

Open AccessArticle

Titanium Nitride as a Plasmonic Material from Near-Ultraviolet to Very-Long-Wavelength Infrared Range

by Jarosław Judek, Piotr Wróbel, Paweł Piotr Michałowski, Monika Ożga, Bartłomiej Witkowski, Aleksandra Seweryn, Michał Struzik, Cezariusz Jastrzębski and Krzysztof Zberecki

Materials 2021, 14(22), 7095; https://doi.org/10.3390/ma14227095 - 22 Nov 2021

Cited by 21 | Viewed by 4508

Abstract

Titanium nitride is a well-known conductive ceramic material that has recently experienced resumed attention because of its plasmonic properties comparable to metallic gold and silver. Thus, TiN is an attractive alternative for modern and future photonic applications that require compatibility with the Complementary [...] Read more.

Titanium nitride is a well-known conductive ceramic material that has recently experienced resumed attention because of its plasmonic properties comparable to metallic gold and silver. Thus, TiN is an attractive alternative for modern and future photonic applications that require compatibility with the Complementary Metal-Oxide-Semiconductor (CMOS) technology or improved resistance to temperatures or radiation. This work demonstrates that polycrystalline TiN_x films sputtered on silicon at room temperature can exhibit plasmonic properties continuously from 400 nm up to 30 μm. The films’ composition, expressed as nitrogen to titanium ratio x and determined in the Secondary Ion Mass Spectroscopy (SIMS) experiment to be in the range of 0.84 to 1.21, is essential for optimizing the plasmonic properties. In the visible range, the dielectric function renders the interband optical transitions. For wavelengths longer than 800 nm, the optical properties of TiN_x are well described by the Drude model modified by an additional Lorentz term, which has to be included for part of the samples. The ab initio calculations support the experimental results both in the visible and infra-red ranges; particularly, the existence of a very low energy optical transition is predicted. Some other minor features in the dielectric function observed for the longest wavelengths are suspected to be of phonon origin. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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16 pages, 6538 KiB

Open AccessArticle

Influence of Spatial Dispersion on Propagation Properties of Waveguides Based on Hyperbolic Metamaterial

by Bartosz Janaszek, Anna Tyszka-Zawadzka and Paweł Szczepański

Materials 2021, 14(22), 6885; https://doi.org/10.3390/ma14226885 - 15 Nov 2021

Cited by 3 | Viewed by 1758

Abstract

In this work, we study the effect of spatial dispersion on propagation properties of planar waveguides with the core layer formed by hyperbolic metamaterial (HMM). In our case, the influence of spatial dispersion was controlled by changing the unit cell’s dimensions. Our analysis [...] Read more.

In this work, we study the effect of spatial dispersion on propagation properties of planar waveguides with the core layer formed by hyperbolic metamaterial (HMM). In our case, the influence of spatial dispersion was controlled by changing the unit cell’s dimensions. Our analysis revealed a number of new effects arising in the considered waveguides, which cannot be predicted with the help of local approximation, including mode degeneration (existence of additional branch of TE and TM high-β modes), power flow inversion, propagation gap, and plasmonic-like modes characterized with long distance propagation. Additionally, for the first time we reported unusual characteristic points appearing for the high-β TM mode of each order corresponding to a single waveguide width for which power flow tends to zero and mode stopping occurs. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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12 pages, 5363 KiB

Open AccessArticle

Investigation of Electrical Properties of the Al/SiO₂/n⁺⁺-Si Resistive Switching Structures by Means of Static, Admittance, and Impedance Spectroscopy Measurements

by Piotr Wiśniewski, Jakub Jasiński, Andrzej Mazurak, Bartłomiej Stonio and Bogdan Majkusiak

Materials 2021, 14(20), 6042; https://doi.org/10.3390/ma14206042 - 13 Oct 2021

Cited by 9 | Viewed by 2541

Abstract

In this study, the resistive switching phenomenon in Al/SiO2/n⁺⁺-Si structures is observed and studied by means of DC, small-signal admittance, and complex impedance spectroscopy measurements. Possible transport mechanisms in the high and low resistance states are identified. Based on the results [...] Read more.

In this study, the resistive switching phenomenon in Al/SiO2/n⁺⁺-Si structures is observed and studied by means of DC, small-signal admittance, and complex impedance spectroscopy measurements. Possible transport mechanisms in the high and low resistance states are identified. Based on the results of the applied measurement techniques, an electrical equivalent circuit of the structure is proposed. We discuss the effect of parasitic elements influencing the measurement results and show that a proper model can give useful information about the electrical properties of the device. A good agreement between the characteristics of the proposed equivalent circuit and the experimental data, based on different measurement procedures, confirms the validity of the used methodology and its applicability to the electrical characterization of RRAMs. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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14 pages, 16379 KiB

Open AccessArticle

Investigations of Structural and Electrical Properties of ALD Films Formed with the Ozone Precursor

by Aleksandra Seweryn, Krystyna Lawniczak-Jablonska, Piotr Kuzmiuk, Sylwia Gieraltowska, Marek Godlewski and Robert Mroczynski

Materials 2021, 14(18), 5395; https://doi.org/10.3390/ma14185395 - 18 Sep 2021

Cited by 6 | Viewed by 2503

Abstract

The continuous development of ALD thin films demands ongoing improvements and changes toward fabricating materials with tailored properties that are suitable for different practical applications. Ozone has been recently established as a precursor, with distinct advantages over the alternative oxidizing precursors in the [...] Read more.

The continuous development of ALD thin films demands ongoing improvements and changes toward fabricating materials with tailored properties that are suitable for different practical applications. Ozone has been recently established as a precursor, with distinct advantages over the alternative oxidizing precursors in the ALDs of advanced dielectric films. This study reports alumina (Al₂O₃) and hafnia (HfO₂) formation using an O₃ source and compares the obtained structural and electrical properties. The performed structural examinations of ozone-based materials proved homogenous high-k films with less vacancy levels compared to water-based films. The enhanced structural properties also result in the problematic incorporation of different dopants through the bulk layer. Furthermore, analysis of electrical characteristics of the MIS structures with ALD gate dielectrics demonstrated the improved quality and good insulating properties of ozone-based films. However, further optimization of the ALD technique with ozone is needed as a relatively low relative permittivity characterizes the ultra-thin films. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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13 pages, 3651 KiB

Open AccessArticle

Distributed Feedback Laser Based on Tunable Photonic Hypercrystal

by Bartosz Janaszek and Paweł Szczepański

Materials 2021, 14(15), 4065; https://doi.org/10.3390/ma14154065 - 21 Jul 2021

Cited by 15 | Viewed by 1928

Abstract

In this work, we investigate the generation of light in a distributed feedback (DFB) laser composed of periodically arranged layers of hyperbolic medium and active material forming a 1D photonic hypercrystal (PHC). The scope of our study covers the analysis of laser action [...] Read more.

In this work, we investigate the generation of light in a distributed feedback (DFB) laser composed of periodically arranged layers of hyperbolic medium and active material forming a 1D photonic hypercrystal (PHC). The scope of our study covers the analysis of laser action in the presence of different types of dispersion that are achievable in a hyperbolic medium. Using the example of a PHC structure consisting of graphene-based hyperbolic medium, we demonstrate the possibility of controlling laser action by tuning effective dispersion. Our analysis reveals the possibility of obtaining a single-frequency generation with high side-mode suppression and controllable wavelength of operation. Moreover, we present a new mechanism for the modulation of laser amplitude arising from voltage-controllable dispersion of hyperbolic medium. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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14 pages, 2644 KiB

Open AccessArticle

Optical Transitions and Excited State Absorption Cross Sections of SrLaGaO₄ Doped with Ho³⁺ Ions

by Marcin Kaczkan and Michał Malinowski

Materials 2021, 14(14), 3831; https://doi.org/10.3390/ma14143831 - 8 Jul 2021

Cited by 5 | Viewed by 2290

Abstract

The spectroscopic properties of SrLaGaO₄ (SLO) crystal doped with Ho³⁺ ions were studied in this work. Absorption, emission spectra and decay dynamics of excited states have been measured and discussed using the Judd–Ofelt model. Photoluminescence emissions were attributed to transitions from [...] Read more.

The spectroscopic properties of SrLaGaO₄ (SLO) crystal doped with Ho³⁺ ions were studied in this work. Absorption, emission spectra and decay dynamics of excited states have been measured and discussed using the Judd–Ofelt model. Photoluminescence emissions were attributed to transitions from the excited ³D₃, ⁵S₂, ⁵F₅, ⁵I₆ and ⁵I₇ multiplet manifolds. The experimental lifetimes for five excited states have been compared to the theoretical values, calculated using Judd–Ofelt theory, allowing for the determination of the multiphonon relaxation rates (W_nR) of the respective states. The experimental data were approximately on a line expressed by W_nR = W₀ exp(−αΔE) with W₀ = 0.5 × 10⁷ s⁻¹ and α = 2.6 × 10⁻³ cm. To discuss the excited state absorption (ESA) pathways, that originated from several excited levels, we used the Judd–Ofelt formalism allowing determination of the integrated cross section for ESA transitions. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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12 pages, 3732 KiB

Open AccessArticle

Nonlocality-Enabled Magnetic Free Optical Isolation in Hyperbolic Metamaterials

by Bartosz Janaszek, Marcin Kieliszczyk and Paweł Szczepański

Materials 2021, 14(11), 2865; https://doi.org/10.3390/ma14112865 - 27 May 2021

Cited by 4 | Viewed by 2130

Abstract

Hereby, we present an optical isolator (optical diode) based on a hyperbolic metamaterial (HMM). We demonstrate that a grating-free planar linear non-magnetic HMM structure deposited on a high-index substrate, which, due to presence of strong spatial dispersion (non-locality), reveals asymmetrical transmittance and reflectance [...] Read more.

Hereby, we present an optical isolator (optical diode) based on a hyperbolic metamaterial (HMM). We demonstrate that a grating-free planar linear non-magnetic HMM structure deposited on a high-index substrate, which, due to presence of strong spatial dispersion (non-locality), reveals asymmetrical transmittance and reflectance characteristics for light of arbitrary polarization within a wide angular and spectral range. The presented device may be efficiently utilized to completely block backward and enforce unidirectional propagation in free space and integrated systems without the use of magnetooptical or non-linear effects. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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13 pages, 4419 KiB

Open AccessArticle

Down-Shifting in the YAM: Ce³⁺ + Yb³⁺ System for Solar Cells

by Bartosz Fetliński, Sebastian Turczyński, Michał Malinowski and Paweł Szczepański

Materials 2021, 14(11), 2753; https://doi.org/10.3390/ma14112753 - 23 May 2021

Cited by 8 | Viewed by 2232

Abstract

In this work, we investigate Ce³⁺ to Yb³⁺ energy transfer in Y₄Al₂O₉ (YAM) for potential application in solar spectrum down-converting layers for photovoltaic devices. Photoluminescence properties set, of 10 samples, of the YAM host activated with [...] Read more.

In this work, we investigate Ce³⁺ to Yb³⁺ energy transfer in Y₄Al₂O₉ (YAM) for potential application in solar spectrum down-converting layers for photovoltaic devices. Photoluminescence properties set, of 10 samples, of the YAM host activated with Ce³⁺ and Yb³⁺ with varying concentrations are presented, and the Ce³⁺ to Yb³⁺ energy transfer is proven. Measurement of highly non-exponential luminescence decays of Ce³⁺ 5d band allowed for the calculation of maximal theoretical quantum efficiency, of the expected down-conversion process, equal to 123%. Measurements of Yb³⁺ emission intensity, in the function of excitation power, confirmed the predominantly single-photon downshifting character of Ce³⁺ to Yb³⁺ energy transfer. Favorable location of the Ce³⁺ 5d bands in YAM makes this system a great candidate for down-converting, and down-shifting, luminescent layers for photovoltaics. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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Review

Jump to: Research

23 pages, 4571 KiB

Open AccessReview

A Review: Inductively Coupled Plasma Reactive Ion Etching of Silicon Carbide

by Katarzyna Racka-Szmidt, Bartłomiej Stonio, Jarosław Żelazko, Maciej Filipiak and Mariusz Sochacki

Materials 2022, 15(1), 123; https://doi.org/10.3390/ma15010123 - 24 Dec 2021

Cited by 63 | Viewed by 14671

Abstract

The inductively coupled plasma reactive ion etching (ICP-RIE) is a selective dry etching method used in fabrication technology of various semiconductor devices. The etching is used to form non-planar microstructures—trenches or mesa structures, and tilted sidewalls with a controlled angle. The ICP-RIE method [...] Read more.

The inductively coupled plasma reactive ion etching (ICP-RIE) is a selective dry etching method used in fabrication technology of various semiconductor devices. The etching is used to form non-planar microstructures—trenches or mesa structures, and tilted sidewalls with a controlled angle. The ICP-RIE method combining a high finishing accuracy and reproducibility is excellent for etching hard materials, such as SiC, GaN or diamond. The paper presents a review of silicon carbide etching—principles of the ICP-RIE method, the results of SiC etching and undesired phenomena of the ICP-RIE process are presented. The article includes SEM photos and experimental results obtained from different ICP-RIE processes. The influence of O₂ addition to the SF₆ plasma as well as the change of both RIE and ICP power on the etching rate of the Cr mask used in processes and on the selectivity of SiC/Cr etching are reported for the first time. SiC is an attractive semiconductor with many excellent properties, that can bring huge potential benefits thorough advances in submicron semiconductor processing technology. Recently, there has been an interest in SiC due to its potential wide application in power electronics, in particular in automotive, renewable energy and rail transport. Full article

(This article belongs to the Special Issue Trends in Electronic and Optoelectronic Materials)

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