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12 pages, 2083 KiB

Open AccessArticle

Influence of Thin Film Deposition on AFM Cantilever Tips in Adhesion and Young’s Modulus of MEMS Surfaces

by Pedram Heidari, Majid Salehi, Behrooz Ruhani, Violeta Purcar and Simona Căprărescu

Materials 2022, 15(6), 2102; https://doi.org/10.3390/ma15062102 - 12 Mar 2022

Cited by 8 | Viewed by 2979

Adhesion is a critical factor in microelectromechanical systems (MEMSs) and is influenced by many parameters. In important fields, such as microassembly, an improved understanding of adhesion can result in higher precision. This study examines the influence of deposition of gold and titanium onto [...] Read more.

Adhesion is a critical factor in microelectromechanical systems (MEMSs) and is influenced by many parameters. In important fields, such as microassembly, an improved understanding of adhesion can result in higher precision. This study examines the influence of deposition of gold and titanium onto the atomic force microscope (AFM) tips in adhesion forces and Young’s modulus, between a few MEMS substrates (silicon, gold, and silver) and the AFM tips. It was found that, except for gold substrate, an AFM tip coated with gold has the highest adhesion force of 42.67 nN for silicon substrates, whereas the titanium-coated AFM tip decreases the force for all the samples. This study suggests that such changes must be taken into account while studying the adhesion force. The final results indicate that utilizing gold substrate with titanium AFM tip led to the lowest adhesion force, which could be useful in adhesion force measurement during microassembly. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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11 pages, 2961 KiB

Open AccessArticle

Influence of the Microstructure and Optical Constants on Plasmonic Properties of Copper Nanolayers

by Tomasz Rerek, Beata Derkowska-Zielinska, Marek Trzcinski, Robert Szczesny, Mieczyslaw K. Naparty and Lukasz Skowronski

Materials 2021, 14(23), 7292; https://doi.org/10.3390/ma14237292 - 29 Nov 2021

Viewed by 1581

Abstract

Copper layers with thicknesses of 12, 25, and 35 nm were thermally evaporated on silicon substrates (Si

_{(100)}

) with two different deposition rates 0.5 and 5.0 Å/s. The microstructure of produced coatings was studied using atomic force microscopy (AFM) and [...] Read more.

Copper layers with thicknesses of 12, 25, and 35 nm were thermally evaporated on silicon substrates (Si

_{(100)}

) with two different deposition rates 0.5 and 5.0 Å/s. The microstructure of produced coatings was studied using atomic force microscopy (AFM) and powder X-ray diffractometer (XRD). Ellipsometric measurements were used to determine the effective dielectric functions <

\tilde{ε}

> as well as the quality indicators of the localized surface plasmon (LSP) and the surface plasmon polariton (SPP). The composition and purity of the produced films were analysed using X-ray photoelectron spectroscopy (XPS). Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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15 pages, 2178 KiB

Open AccessArticle

Microstructure and Optical Properties of Nanostructural Thin Films Fabricated through Oxidation of Au–Sn Intermetallic Compounds

by Lukasz Skowronski, Marek Trzcinski, Aleksandra Olszewska and Robert Szczesny

Materials 2021, 14(14), 4034; https://doi.org/10.3390/ma14144034 - 19 Jul 2021

Cited by 7 | Viewed by 2641

Abstract

AuSn and AuSn₂ thin films (5 nm) were used as precursors during the formation of semiconducting metal oxide nanostructures on a silicon substrate. The nanoparticles were produced in the processes of annealing and oxidation of gold–tin intermetallic compounds under ultra-high vacuum conditions. [...] Read more.

AuSn and AuSn₂ thin films (5 nm) were used as precursors during the formation of semiconducting metal oxide nanostructures on a silicon substrate. The nanoparticles were produced in the processes of annealing and oxidation of gold–tin intermetallic compounds under ultra-high vacuum conditions. The formation process and morphology of a mixture of SnO₂ and Au@SnO_x (the core–shell structure) nanoparticles or Au nanocrystalites were carefully examined by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy (EDX). The annealing and oxidation of the thin film of the AuSn intermetallic compound led to the formation of uniformly distributed structures with a size of ∼20–30 nm. All of the synthesized nanoparticles exhibited a strong absorption band at 520–530 nm, which is typical for pure metallic or metal oxide systems. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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12 pages, 8232 KiB

Open AccessArticle

Synthesis of Copper Nitride Layers by the Pulsed Magnetron Sputtering Method Carried out under Various Operating Conditions

by Magdalena Wilczopolska, Katarzyna Nowakowska-Langier, Sebastian Okrasa, Lukasz Skowronski, Roman Minikayev, Grzegorz W. Strzelecki, Rafal Chodun and Krzysztof Zdunek

Materials 2021, 14(10), 2694; https://doi.org/10.3390/ma14102694 - 20 May 2021

Cited by 11 | Viewed by 2729

Abstract

Copper nitride shows various properties that depend on the structure of the material and is influenced by the change in technical parameters. In the present work, Cu–N layers were synthesized using the pulsed magnetron sputtering method. The synthesis was performed under different operating [...] Read more.

Copper nitride shows various properties that depend on the structure of the material and is influenced by the change in technical parameters. In the present work, Cu–N layers were synthesized using the pulsed magnetron sputtering method. The synthesis was performed under different operating conditions: direct current (DC) or alternating current (AC) power supply, and various atmospheres: pure Ar and a mixture of Ar + N₂. The structural properties of the deposited layers were characterized by X-ray diffraction measurements, and Raman spectroscopy and scanning electron microscopy have been performed. Optical properties were also evaluated. The obtained layers showed tightly packed columnar grain features. The kinetics of the layer growth in the AC mode was lower than that observed in the DC mode, and the layers were thinner and more fine-grained. The copper nitride layers were characterized by the one-phase and two-phase polycrystalline structure of the Cu₃N phase with the preferred growth orientation (100). The lattice constant oscillates between 3.808 and 3.815 Å for one-phase and has a value of 3.828 Å for a two-phase structure. Phase composition results were correlated with Raman spectroscopy measurements. Raman spectra exhibited a broad, diffused, and intense signal of Cu₃N phase, with Raman shift located at 628–635 cm⁻¹. Studies on optical properties showed that the energy gap ranged from 2.17 to 2.47 eV. The results showed that controlling technical parameters gives a possibility to optimize the structure and phase composition of deposited layers. The reported changes were discussed and attributed to the properties of the material layers and technology method. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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13 pages, 3693 KiB

Open AccessArticle

Effects of Deposition and Annealing Temperature on the Structure and Optical Band Gap of MoS₂ Films

by Gongying Chen, Benchu Lu, Xinyu Cui and Jianrong Xiao

Materials 2020, 13(23), 5515; https://doi.org/10.3390/ma13235515 - 3 Dec 2020

Cited by 23 | Viewed by 2854

Abstract

In this study, molybdenum disulfide (MoS₂) film samples were prepared at different temperatures and annealed through magnetron sputtering technology. The surface morphology, crystal structure, bonding structure, and optical properties of the samples were characterized and analyzed. The surface of the MoS [...] Read more.

In this study, molybdenum disulfide (MoS₂) film samples were prepared at different temperatures and annealed through magnetron sputtering technology. The surface morphology, crystal structure, bonding structure, and optical properties of the samples were characterized and analyzed. The surface of the MoS₂ films prepared by radio frequency magnetron sputtering is tightly coupled and well crystallized, the density of the films decreases, and their voids and grain size increase with the increase in deposition temperature. The higher the deposition temperature is, the more stable the MoS₂ films deposited will be, and the 200 °C deposition temperature is an inflection point of the film stability. Annealing temperature affects the structure of the films, which is mainly related to sulfur and the growth mechanism of the films. Further research shows that the optical band gaps of the films deposited at different temperatures range from 0.92 eV to 1.15 eV, showing semiconductor bandgap characteristics. The optical band gap of the films deposited at 200 °C is slightly reduced after annealing in the range of 0.71–0.91 eV. After annealing, the optical band gap of the films decreases because of the two exciton peaks generated by the K point in the Brillouin zone of MoS₂. The blue shift of the K point in the Brillouin zone causes a certain change in the optical band gap of the films. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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11 pages, 3994 KiB

Open AccessArticle

Preparation of Copper Nitride Films with Superior Photocatalytic Activity through Magnetron Sputtering

by Aihua Jiang, Hongjuan Shao, Liwen Zhu, Songshan Ma and Jianrong Xiao

Materials 2020, 13(19), 4325; https://doi.org/10.3390/ma13194325 - 28 Sep 2020

Cited by 10 | Viewed by 2654

Abstract

TiO₂ possesses a wide forbidden band of about 3.2 eV, which severely limits its visible light absorption efficiency. In this work, copper nitride (Cu₃N) films were prepared by magnetron sputtering at different gas flow ratios. The structure of the films [...] Read more.

TiO₂ possesses a wide forbidden band of about 3.2 eV, which severely limits its visible light absorption efficiency. In this work, copper nitride (Cu₃N) films were prepared by magnetron sputtering at different gas flow ratios. The structure of the films was tested by scanning electron microscope, X-ray diffractometer, and X-ray photoelectron spectroscope. Optical properties were investigated by UV-vis spectrophotometer and fluorescence spectrometer. Results show that the Cu₃N crystal possesses a typical anti-ReO₃ crystal structure, and the ratio of nitrogen and Cu atoms of the Cu₃N films was adjusted by changing the gas flow ratio. The Cu₃N films possess an optical band gap of about 2.0 eV and energy gap of about 2.5 eV and exhibit excellent photocatalytic activity for degrading methyl orange (degradation ratio of 99.5% in 30 min). The photocatalytic activity of Cu₃N mainly originates from vacancies in the crystal and Cu self-doping. This work provides a route to broaden the forbidden band width of photocatalytic materials and increase their photoresponse range. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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13 pages, 3866 KiB

Open AccessArticle

Laser-Assisted Synthesis and Oxygen Generation of Nickel Nanoparticles

by Jakub Wawrzyniak, Jakub Karczewski, Jacek Ryl, Katarzyna Grochowska and Katarzyna Siuzdak

Materials 2020, 13(18), 4068; https://doi.org/10.3390/ma13184068 - 13 Sep 2020

Cited by 6 | Viewed by 2784

Abstract

Nowadays, more than ever, environmental awareness is being taken into account when it comes to the design of novel materials. Herein, the pathway to the creation of a colloid of spherical, almost purely metallic nickel nanoparticles (NPs) through pulsed laser ablation in ethanol [...] Read more.

Nowadays, more than ever, environmental awareness is being taken into account when it comes to the design of novel materials. Herein, the pathway to the creation of a colloid of spherical, almost purely metallic nickel nanoparticles (NPs) through pulsed laser ablation in ethanol is presented. A complex description of the colloid is provided through UV-vis spectroscopy and dynamic light scattering analysis, ensuring insight into laser-induced nanoparticle homogenization and size-control of the NPs. The transmission electron spectroscopy revealed spherical nanoparticles with a narrow size distribution, whereas the energy-dispersive X-ray spectroscopy accompanied by the X-ray photoelectron spectroscopy revealed their metallic nature. Furthermore, an example of the application of the colloidal nanoparticles is presented, where a quick, five-min ultrasound modification results in over an order of magnitude higher current densities in the titania-based electrode for the oxygen evolution reaction. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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9 pages, 3288 KiB

Open AccessArticle

Preparation of Cu₃N/MoS₂ Heterojunction through Magnetron Sputtering and Investigation of Its Structure and Optical Performance

by Liwen Zhu, Xiu Cao, Chenyang Gong, Aihua Jiang, Yong Cheng and Jianrong Xiao

Materials 2020, 13(8), 1873; https://doi.org/10.3390/ma13081873 - 16 Apr 2020

Cited by 19 | Viewed by 3119

Abstract

Cu₃N/MoS₂ heterojunction was prepared through magnetron sputtering, and its optical band gap was investigated. Results showed that the prepared Cu₃N/MoS₂ heterojunction had a clear surface heterojunction structure, uniform surface grains, and no evident cracks. The optical band [...] Read more.

Cu₃N/MoS₂ heterojunction was prepared through magnetron sputtering, and its optical band gap was investigated. Results showed that the prepared Cu₃N/MoS₂ heterojunction had a clear surface heterojunction structure, uniform surface grains, and no evident cracks. The optical band gap (1.98 eV) of Cu₃N/MoS₂ heterojunction was obtained by analyzing the ultraviolet-visible transmission spectrum. The valence and conduction band offsets of Cu₃N/MoS₂ heterojunction were 1.42 and 0.82 eV, respectively. The Cu₃N film and multilayer MoS₂ formed a type-II heterojunction. After the two materials adhered to form the heterojunction, the interface electrons flowed from MoS₂ to Cu₃N because the latter had higher Fermi level than the former. This behavior caused the formation of additional electrons in the Cu₃N and MoS₂ layers and the change in optical band gap, which was conducive to the charge separation of electrons in MoS₂ or MoS₂ holes. The prepared Cu₃N/MoS₂ heterojunction has potential application in various high-performance photoelectric devices, such as photocatalysts and photodetectors. Full article

(This article belongs to the Special Issue Optical Characterization and Applications of Metallic Thin Films)

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