Advanced Thin-Films: Design, Fabrication and Applications, 2nd Edition

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

Deadline for manuscript submissions: 30 September 2024 | Viewed by 5135

Special Issue Editor


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Guest Editor
1. Laboratory of Complex Electrophysic Investigations, Institute of Electrophysics, Ural Branch, Russian Academy of Sciences, Yekaterinburg 620016, Russia
2. Department of Physical and Inorganic Chemistry, Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg 620002, Russia
Interests: solid oxide fuel cells (SOFC); thin-film technology; electrophoretic deposition (EPD); stable suspensions; nanoscale materials; electrochemical properties
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Special Issue Information

Dear Colleagues,

We would like to invite you to submit to a Special Issue on "Advanced Thin-Films: Design, Fabrication and Applications, 2nd Edition". Thin films play an important role in micromachines development, creating new and unique properties. The purpose of this Special Issue is to present the latest experimental and theoretical developments in the application of advanced thin films based on new functional materials. Authors are invited to submit their latest results; both original research papers and reviews are welcome. Topics of interest include but are not limited to:

  • Latest theoretical and experimental studies in the field of the formation of advanced thin-films for novel applications such as Nano/Microelectromechanical Systems (N/MEMS); transducers; actuators; electrochemical devices (fuel cells, batteries, supercapacitors, electrolyzers, chemical sensors); optoelectronic devices and catalytic reactors.
  • Fundamental multiphysics and electrochemical/electrokinetic phenomena in the fields such as micro/nano structures; nanoscale materials; surfaces and interface effects.
  • Micro/nano fabrication technology: thin films depositions; surface micromachining; 3D printing and additive manufacturing.
  • Methods of computer simulation of thin films devices.
  • Promising materials for the production of advanced thin-films.

Dr. Elena Kalinina
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. Micromachines is an international peer-reviewed open access monthly 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 2600 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

  • thin-film technology
  • nano/microelectromechanical systems
  • transducers
  • actuators
  • electrochemical devices
  • micro/nanostructures
  • nanoscale materials

Related Special Issue

Published Papers (5 papers)

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Research

11 pages, 3764 KiB  
Article
Enhancing the Uniformity of a Memristor Using a Bilayer Dielectric Structure
by Yulin Liu, Qilai Chen, Yanbo Guo, Bingjie Guo, Gang Liu, Yanchao Liu, Lei He, Yutong Li, Jingyan He and Minghua Tang
Micromachines 2024, 15(5), 605; https://doi.org/10.3390/mi15050605 - 30 Apr 2024
Viewed by 511
Abstract
Resistive random access memory (RRAM) holds great promise for in-memory computing, which is considered the most promising strategy for solving the von Neumann bottleneck. However, there are still significant problems in its application due to the non-uniform performance of RRAM devices. In this [...] Read more.
Resistive random access memory (RRAM) holds great promise for in-memory computing, which is considered the most promising strategy for solving the von Neumann bottleneck. However, there are still significant problems in its application due to the non-uniform performance of RRAM devices. In this work, a bilayer dielectric layer memristor was designed based on the difference in the Gibbs free energy of the oxide. We fabricated Au/Ta2O5/HfO2/Ta/Pt (S3) devices with excellent uniformity. Compared with Au/HfO2/Pt (S1) and Au/Ta2O5/Pt (S2) devices, the S3 device has a low reset voltage fluctuation of 2.44%, and the resistive coefficients of variation are 13.12% and 3.84% in HRS and LRS, respectively, over 200 cycles. Otherwise, the bilayer device has better linearity and more conductance states in multi-state regulation. At the same time, we analyze the physical mechanism of the bilayer device and provide a physical model of ion migration. This work provides a new idea for designing and fabricating resistive devices with stable performance. Full article
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12 pages, 5028 KiB  
Article
Wafer-Scale Characterization of 1692-Pixel-Per-Inch Blue Micro-LED Arrays with an Optimized ITO Layer
by Eun-Kyung Chu, Eun Jeong Youn, Hyun Woong Kim, Bum Doo Park, Ho Kun Sung and Hyeong-Ho Park
Micromachines 2024, 15(5), 560; https://doi.org/10.3390/mi15050560 - 24 Apr 2024
Viewed by 509
Abstract
Wafer-scale blue micro-light-emitting diode (micro-LED) arrays were fabricated with a pixel size of 12 μm, a pixel pitch of 15 μm, and a pixel density of 1692 pixels per inch, achieved by optimizing the properties of e-beam-deposited and sputter-deposited indium tin oxide (ITO). [...] Read more.
Wafer-scale blue micro-light-emitting diode (micro-LED) arrays were fabricated with a pixel size of 12 μm, a pixel pitch of 15 μm, and a pixel density of 1692 pixels per inch, achieved by optimizing the properties of e-beam-deposited and sputter-deposited indium tin oxide (ITO). Although the sputter-deposited ITO (S-ITO) films exhibited a densely packed morphology and lower resistivity compared to the e-beam-deposited ITO (E-ITO) films, the forward voltage (VF) values of a micro-LED with the S-ITO films were higher than those with the E-ITO films. The VF values for a single pixel and for four pixels with E-ITO films were 2.82 V and 2.83 V, respectively, while the corresponding values for S-ITO films were 3.50 V and 3.52 V. This was attributed to ion bombardment damage and nitrogen vacancies in the p-GaN layer. Surprisingly, the VF variations of a single pixel and of four pixels with the optimized E-ITO spreading layer from five different regions were only 0.09 V and 0.10 V, respectively. This extremely uniform VF variation is suitable for creating micro-LED displays to be used in AR and VR applications, circumventing the bottleneck in the development of long-lifespan and high-brightness organic LED devices for industrial mass production. Full article
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17 pages, 4936 KiB  
Article
Analysis of a Flexible Photoconductor, Manufactured with Organic Semiconductor Films
by Luis Alberto Cantera Cantera, María Elena Sánchez Vergara, Leon Hamui, Isidro Mejía Prado, Alejandro Flores Huerta and Teresa Lizet Martínez Plata
Micromachines 2024, 15(4), 446; https://doi.org/10.3390/mi15040446 - 27 Mar 2024
Viewed by 846
Abstract
This work presents the evaluation of the electrical behavior of a flexible photoconductor with a planar heterojunction architecture made up of organic semiconductor films deposited by high vacuum evaporation. The heterojunction was characterized in its morphology and mechanical properties by scanning electron microscopy [...] Read more.
This work presents the evaluation of the electrical behavior of a flexible photoconductor with a planar heterojunction architecture made up of organic semiconductor films deposited by high vacuum evaporation. The heterojunction was characterized in its morphology and mechanical properties by scanning electron microscopy and atomic force microscopy. The electrical characterization was carried out through the approximations of ohmic and SCLC (Space-Charge Limited Current) behaviors using experimental J–V (current density–voltage) curves at different voltages and under different light conditions. The optimization of the photoconductor was carried out through annealing and accelerated lighting processes. With these treatments, the Knoop Hardness of the flexible photoconductor has reached a value of 8 with a tensile strength of 5.7 MPa. The ohmic and SCLC approximations demonstrate that the unannealed device has an ohmic behavior, whereas the annealed device has an SCLC behavior, and after the optimization process, an ohmic behavior and a maximum current density of 0.34 mA/mm2 were obtained under blue light. The approximations of the device’s electron mobility (μn) and free carrier density (n0) were performed under different light conditions, and the electrical activation energy and electrical gap were obtained for the flexible organic device, resulting in appropriate properties for these applications. Full article
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8 pages, 2729 KiB  
Communication
Origin of the High Density of Oxygen Vacancies at the Back Channel of Back-Channel-Etched a-InGaZnO Thin-Film Transistors
by Shimin Ge, Juncheng Xiao, Shan Li, Dong Yuan, Yuhua Dong and Shengdong Zhang
Micromachines 2024, 15(3), 400; https://doi.org/10.3390/mi15030400 - 16 Mar 2024
Viewed by 754
Abstract
This study reveals the pronounced density of oxygen vacancies (Vo) at the back channel of back-channel-etched (BCE) a-InGaZnO (a-IGZO) thin-film transistors (TFTs) results from the sputtered deposition rather than the wet etching process of the source/drain metal, and they are distributed within approximately [...] Read more.
This study reveals the pronounced density of oxygen vacancies (Vo) at the back channel of back-channel-etched (BCE) a-InGaZnO (a-IGZO) thin-film transistors (TFTs) results from the sputtered deposition rather than the wet etching process of the source/drain metal, and they are distributed within approximately 25 nm of the back surface. Furthermore, the existence and distribution depth of the high density of Vo defects are verified by means of XPS spectra analyses. Then, the mechanism through which the above Vo defects lead to the instability of BCE a-IGZO TFTs is elucidated. Lastly, it is demonstrated that the device instability under high-humidity conditions and negative bias temperature illumination stress can be effectively alleviated by etching and thus removing the surface layer of the back channel, which contains the high density of Vo defects. In addition, this etch method does not cause a significant deterioration in the uniformity of electrical characteristics and is quite convenient to implement in practical fabrication processes. Thus, a novel and effective solution to the device instability of BCE a-IGZO TFTs is provided. Full article
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17 pages, 9913 KiB  
Article
Hollow Microcavity Electrode for Enhancing Light Extraction
by Seonghyeon Park, Byeongwoo Kang, Seungwon Lee, Jian Cheng Bi, Jaewon Park, Young Hyun Hwang, Jun-Young Park, Ha Hwang, Young Wook Park and Byeong-Kwon Ju
Micromachines 2024, 15(3), 328; https://doi.org/10.3390/mi15030328 - 27 Feb 2024
Viewed by 1245
Abstract
Luminous efficiency is a pivotal factor for assessing the performance of optoelectronic devices, wherein light loss caused by diverse factors is harvested and converted into the radiative mode. In this study, we demonstrate a nanoscale vacuum photonic crystal layer (nVPCL) for light extraction [...] Read more.
Luminous efficiency is a pivotal factor for assessing the performance of optoelectronic devices, wherein light loss caused by diverse factors is harvested and converted into the radiative mode. In this study, we demonstrate a nanoscale vacuum photonic crystal layer (nVPCL) for light extraction enhancement. A corrugated semi-transparent electrode incorporating a periodic hollow-structure array was designed through a simulation that utilizes finite-difference time-domain computational analysis. The corrugated profile, stemming from the periodic hollow structure, was fabricated using laser interference lithography, which allows the precise engineering of various geometrical parameters by controlling the process conditions. The semi-transparent electrode consisted of a 15 nm thick Ag film, which acted as the exit mirror and induced microcavity resonance. When applied to a conventional green organic light-emitting diode (OLED) structure, the optimized nVPCL-integrated device demonstrated a 21.5% enhancement in external quantum efficiency compared to the reference device. Further, the full width at half maximum exhibited a 27.5% reduction compared to that of the reference device, demonstrating improved color purity. This study presents a novel approach by applying a hybrid thin film electrode design to optoelectronic devices to enhance optical efficiency and color purity. Full article
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