Electronic Materials

Editorial

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2 pages, 155 KiB

Open AccessEditorial

Characterization of Electronic Materials

by Wojciech Pisula

Electron. Mater. 2022, 3(3), 263-264; https://doi.org/10.3390/electronicmat3030022 - 14 Sep 2022

Cited by 1 | Viewed by 2218

Abstract

Electronic materials are of great interest due to their potential to be applied in a broad range of important electronic devices including transistors, sensors, solar cells and others [...] Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

Research

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16 pages, 5074 KiB

Open AccessArticle

Chlorine Adsorption on TiO₂(110)/Water Interface: Nonadiabatic Molecular Dynamics Simulations for Photocatalytic Water Splitting

by Yin-Pai Lin, Dmitry Bocharov, Inta Isakoviča, Vladimir Pankratov, Aleksandr A. Popov, Anatoli I. Popov and Sergei Piskunov

Electron. Mater. 2023, 4(1), 33-48; https://doi.org/10.3390/electronicmat4010004 - 7 Mar 2023

Cited by 6 | Viewed by 2126

Abstract

Chloride is one of the most abundant ions in sea water, which is more available than fresh water. Due to lack of H

_{2}

O adsorbate states near the valence band maximum (VBM) edge, the difficulty of water dissociation incidents has been reported [...] Read more.

Chloride is one of the most abundant ions in sea water, which is more available than fresh water. Due to lack of H

_{2}

O adsorbate states near the valence band maximum (VBM) edge, the difficulty of water dissociation incidents has been reported on the rutile TiO

_{2}

surface as the excitation energy is around the band gap energy of TiO

_{2}

. It is interesting whether the extra chloride can be a benefit to the water dissociation or not. In this study, the models of chlorine adatoms placed on the rutile TiO

_{2}

(110)/water interface are constructed using ab initio methods. The time-dependent spatial charges, bond-lengths of water molecules, and Hirshfeld charges are calculated by real-time time-dependent density functional theory and the Ehrenfest dynamics theory for investigating the excited state nonadiabatic dynamics of water dissociation. This study presents two photoinduced water-splitting pathways related to chlorine and analyzes the photogenerated hole along the reactions. The first step of water dissociation relies on the localized competition of oxygen charges between the dissociated water and the bridge site of TiO

_{2}

for transforming the water into hydroxyl and hydrogen by photoinduced driving force. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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11 pages, 2211 KiB

Open AccessArticle

Stress-Relaxed AlN-Buffer-Oriented GaN-Nano-Obelisks-Based High-Performance UV Photodetector

by Pargam Vashishtha, Pukhraj Prajapat, Lalit Goswami, Aditya Yadav, Akhilesh Pandey and Govind Gupta

Electron. Mater. 2022, 3(4), 357-367; https://doi.org/10.3390/electronicmat3040029 - 9 Dec 2022

Cited by 21 | Viewed by 3085

Abstract

Epitaxial GaN nanostructures are developed, and the influence of the AlN buffer layer (temperature modulation) on material characteristics and optoelectronic device application is assessed. The AlN buffer layer was grown on a Si (111) substrate at varying temperatures (770–830 °C), followed by GaN [...] Read more.

Epitaxial GaN nanostructures are developed, and the influence of the AlN buffer layer (temperature modulation) on material characteristics and optoelectronic device application is assessed. The AlN buffer layer was grown on a Si (111) substrate at varying temperatures (770–830 °C), followed by GaN growth using plasma-assisted molecular beam epitaxy. The investigation revealed that the comparatively lower temperature AlN buffer layer was responsible for stress and lattice strain relaxation and was realized as the GaN nano-obelisk structures. Contrarily, the increased temperature of the AlN growth led to the formation of GaN nanopyramidal and nanowax/wane structures. These grown GaN/AlN/Si heterostructures were utilized to develop photodetectors in a metal–semiconductor–metal geometry format. The performance of these fabricated optoelectronic devices was examined under ultraviolet illumination (UVA), where the GaN nano-obelisks-based device attained the highest responsivity of 118 AW⁻¹. Under UVA (325 nm) illumination, the designed device exhibited a high detectivity of 1 × 10¹⁰ Jones, noise equivalent power of 1 × 10⁻¹² WHz^−1/2, and external quantum efficiency of 45,000%. The analysis revealed that the quality of the AlN buffer layer significantly improved the optoelectronic performance of the device. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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12 pages, 4485 KiB

Open AccessArticle

Effect of Carrier Gas Flow Rates on the Structural and Optical Properties of ZnO Films Deposited Using an Aerosol Deposition Technique

by May Zin Toe, Wai Kian Tan, Hiroyuki Muto, Go Kawamura, Atsunori Matsuda, Khatijah Aisha Binti Yaacob and Swee-Yong Pung

Electron. Mater. 2022, 3(4), 332-343; https://doi.org/10.3390/electronicmat3040027 - 31 Oct 2022

Cited by 4 | Viewed by 2210

Abstract

Aerosol deposition (AD) is a simple, dry raw-powder deposition process in which the targeted film is formed by direct bombardment of accelerated starting powder onto the substrate surface at room temperature. Despite the increased interest in AD film formation, no work has been [...] Read more.

Aerosol deposition (AD) is a simple, dry raw-powder deposition process in which the targeted film is formed by direct bombardment of accelerated starting powder onto the substrate surface at room temperature. Despite the increased interest in AD film formation, no work has been completed to systematically investigate the formation of dense zinc oxide (ZnO) films using the AD method and their optical properties. Therefore, this study was carried out to investigate the effect of AD gas flow rate on the formation of AD films and the optical properties of aerosol-deposited ZnO films. ZnO films with nanosized (<40 nm) crystallites were successfully deposited on FTO substrates at room temperature. A dense and uniform layer of aerosol-deposited ZnO films with a roughened surface was obtained without subsequent heat treatment. With the increase in the AD gas flow rate, the crystal size and the AD film’s thickness were reduced. The Raman spectroscopy verified that the thin film was of a ZnO wurtzite structure. The room temperature photoluminescence of the ZnO thin film produced strong visible emissions. The findings of this work demonstrated that AD can be an alternative technique for the rapid deposition of dense and thick ZnO films for optoelectronic applications. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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10 pages, 1843 KiB

Open AccessFeature PaperArticle

Direct Comparison of the Effect of Processing Conditions in Electrolyte-Gated and Bottom-Gated TIPS-Pentacene Transistors

by Nicolò Lago, Marco Buonomo, Federico Prescimone, Stefano Toffanin, Michele Muccini and Andrea Cester

Electron. Mater. 2022, 3(4), 281-290; https://doi.org/10.3390/electronicmat3040024 - 27 Sep 2022

Cited by 1 | Viewed by 2298

Abstract

Among the plethora of soluble and easy processable organic semiconductors, 6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-P5) is one of the most promising materials for next-generation flexible electronics. However, based on the information reported in the literature, it is difficult to exploit in field-effect transistors the high-performance characteristics [...] Read more.

Among the plethora of soluble and easy processable organic semiconductors, 6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-P5) is one of the most promising materials for next-generation flexible electronics. However, based on the information reported in the literature, it is difficult to exploit in field-effect transistors the high-performance characteristics of this material. This article correlates the HMDS functionalization of the silicon substrate with the electrical characteristics of TIPS-P5-based bottom gate organic field-effect transistors (OFETs) and electrolyte-gated organic field-effect transistors (EGOFETs) fabricated over the same platform. TIPS-P5 transistors with a double-gate architecture were fabricated by simple drop-casting on Si/SiO₂ substrates, and the substrates were either functionalized with hexamethyldisilazane (HMDS) or left untreated. The same devices were characterized both as standard bottom-gate transistors and as (top-gate) electrolyte-gated transistors, and the results with and without HMDS treatment were compared. It is shown that the functionalization of the silicon substrate negatively influences EGOFETs performance, while it is beneficial for bottom-gate OFETs. Different device architectures (e.g., bottom-gate vs. top-gate) require specific evaluation of the fabrication protocols starting from the effect of the HMDS functionalization to maximize the electrical characteristics of TIPS-P5-based devices. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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11 pages, 42615 KiB

Open AccessArticle

A Study on the Optimization of the Conductive Ball Manufacturing Process, Used for Anisotropic Conductive Films

by Jong-Keun Choi, Young-Gyun Kim and Kwan-Young Han

Electron. Mater. 2022, 3(3), 252-262; https://doi.org/10.3390/electronicmat3030021 - 19 Aug 2022

Viewed by 2081

Abstract

Currently, as the next-generation of display progresses—with high performance and high integration—the surface mounting technology of components is very important. In particular, in the case of flexible displays, such as rollable and bendable displays, ACF that connects wires to any curvature is essential. [...] Read more.

Currently, as the next-generation of display progresses—with high performance and high integration—the surface mounting technology of components is very important. In particular, in the case of flexible displays, such as rollable and bendable displays, ACF that connects wires to any curvature is essential. However, the conductive ball used inside the ACF has had problems with particle size and non-uniform metal coating. It was confirmed that the presence of solvent and oxygen, which are used in polymer synthesis, affects the sphere formation of polymer beads. By optimizing the factors affecting the polymer beads, a perfect spherical polymer bead was manufactured. In addition, the conductive ball manufacturing process was optimized by confirming the factors affecting the metal coating. The metal coating on the surface of the polymer bead was applied with a uniform thickness by considering the specific surface area and concentration of the conductive balls, and, through this optimized process, conductive balls for anisotropic conductive films with uniform size and metal thickness were obtained. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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16 pages, 3798 KiB

Open AccessArticle

Hydrodynamic and Energy Transport Model-Based Hot-Carrier Effect in GaAs pin Solar Cell

by Tomah Sogabe, Kodai Shiba and Katsuyoshi Sakamoto

Electron. Mater. 2022, 3(2), 185-200; https://doi.org/10.3390/electronicmat3020016 - 11 May 2022

Cited by 1 | Viewed by 2580

Abstract

The hot-carrier effect and hot-carrier dynamics in GaAs solar cell device performance were investigated. Hot-carrier solar cells based on the conventional operation principle were simulated based on the detailed balance thermodynamic model and the hydrodynamic energy transportation model. A quasi-equivalence between these two [...] Read more.

The hot-carrier effect and hot-carrier dynamics in GaAs solar cell device performance were investigated. Hot-carrier solar cells based on the conventional operation principle were simulated based on the detailed balance thermodynamic model and the hydrodynamic energy transportation model. A quasi-equivalence between these two models was demonstrated for the first time. In the simulation, a specially designed GaAs solar cell was used, and an increase in the open-circuit voltage was observed by increasing the hot-carrier energy relaxation time. A detailed analysis was presented regarding the spatial distribution of hot-carrier temperature and its interplay with the electric field and three hot-carrier recombination processes: Auger, Shockley–Read–Hall, and radiative recombinations. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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18 pages, 4030 KiB

Open AccessArticle

Copper-Content Dependent Structural and Electrical Properties of CZTS Films Formed by “Green” Colloidal Nanocrystals

by Volodymyr Dzhagan, Oleksandr Selyshchev, Serhiy Kondratenko, Nazar Mazur, Yevhenii Havryliuk, Oleksandra Raievska, Oleksandr Stroyuk and Dietrich R. T. Zahn

Electron. Mater. 2022, 3(1), 136-153; https://doi.org/10.3390/electronicmat3010013 - 20 Mar 2022

Cited by 4 | Viewed by 3054

Abstract

Thin films of colloidal CZTS nanocrystals (NCs) synthesized using a “green” approach in water with a variation of the copper-to-tin ratio are investigated by Raman scattering, mid-infrared (molecular vibrations) and near-infrared (free carrier) absorption, X-ray photoemission spectroscopy (XPS), electrical conductivity, and conductive atomic [...] Read more.

Thin films of colloidal CZTS nanocrystals (NCs) synthesized using a “green” approach in water with a variation of the copper-to-tin ratio are investigated by Raman scattering, mid-infrared (molecular vibrations) and near-infrared (free carrier) absorption, X-ray photoemission spectroscopy (XPS), electrical conductivity, and conductive atomic force microscopy (cAFM). We determined the effect of the actual Cu content on the phonon spectra, electrical conductivity, and spectral parameters of the plasmon band. An increase in the electrical conductivity of the NC films upon annealing at 220 °C is explained by three factors: formation of a Cu_xS nanophase at the CZTS NC surface, partial removal of ligands, and improved structural perfection. The presence of the Cu_xS phase is concluded to be the determinant factor for the CZTS NC film conductivity. Cu_xS can be reliably detected based on the analysis of the modified Auger parameter of copper, derived from XPS data and corroborated by Raman spectroscopy data. Partial removal of the ligand is concluded from the agreement of the core-level XPS and vibrational IR spectra. The degree of lattice perfection can be conveniently assessed from the Raman data as well. Further important information derived from a combination of photoelectron and optical data is the work function, ionization potential, and electron affinity of the NC films. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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12 pages, 1904 KiB

Open AccessFeature PaperArticle

Investigation of Elastic Properties of WO₃ Thin Films Supported on Quartz in Surface Acoustic Wave Sensing Devices

by Madjid Arab, Véronique Madigou, Virginie Chevallier, Christian Turquat and Christine Leroux

Electron. Mater. 2022, 3(1), 124-135; https://doi.org/10.3390/electronicmat3010012 - 17 Mar 2022

Cited by 3 | Viewed by 2679

Abstract

This study aims to discuss the combined theoretical and experimental results of elastic properties of tungsten trioxide films supported on Quartz (YX)/45°/10° resonator to form surface acoustic wave (SAW) devices. The SAW systems with different thicknesses of WO₃ thin films were imaged [...] Read more.

This study aims to discuss the combined theoretical and experimental results of elastic properties of tungsten trioxide films supported on Quartz (YX)/45°/10° resonator to form surface acoustic wave (SAW) devices. The SAW systems with different thicknesses of WO₃ thin films were imaged and structurally characterized by X-ray diffraction, atomic force, and transmission electron microscopy. The deposited WO₃ films (100, 200, and 300 nm of thickness) crystallized in a single monoclinic phase. The acoustoelectric properties of the SAW system were obtained by combining theoretical simulations with experimental measurements. The modeling of the SAW devices has been performed by the finite element and boundary element methods (FEM/BEM). The elastic constants of the films at room temperature were assessed via electrical admittances experiments in light of theoretical calculations. The gravimetric effect of the deposited layers is observed by a shift of the resonance frequency to lower values as the thickness of the films increases. Moreover, the acoustic losses are affected by the dielectric losses of the WO₃ films while the resonant frequency decreases almost linearly. SAW devices revealed strong displacement fields with low acoustic losses as a function of WO₃ thicknesses. For all the deposited layers, the measured Young’s moduli and Poisson’s ratios are 8 GPa and 0.5, respectively. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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Review

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16 pages, 8345 KiB

Open AccessReview

Recent Research Process of Carbon Engineering on Na₃V₂(PO₄)₃ for Sodium-Ion Battery Cathodes: A Mini Review

by Yaxuan He and Haibo Li

Electron. Mater. 2023, 4(1), 17-32; https://doi.org/10.3390/electronicmat4010003 - 31 Jan 2023

Cited by 5 | Viewed by 3049

Abstract

Owing to the 3D open framework, excellent structural stability, and high ionic conductivity, NASICON-type compounds are extensively employed as promising cathode materials for sodium-ion batteries (SIBs). Being one of the representative NASICON-type compounds, the Na₃V₂(PO₄)₃ delivers [...] Read more.

Owing to the 3D open framework, excellent structural stability, and high ionic conductivity, NASICON-type compounds are extensively employed as promising cathode materials for sodium-ion batteries (SIBs). Being one of the representative NASICON-type compounds, the Na₃V₂(PO₄)₃ delivers high theoretical capacity with an operating voltage exceeding 3.3 V, enabling it to be a good candidate for SIBs. Unfortunately, the Na₃V₂(PO₄)₃ suffers from low electronic conductivity. In this work, we briefly review the recent research progress on novel carbon engineering strategies to enhance the electronic conductivity of Na₃V₂(PO₄)₃. Moreover, we will point out the issues relating to the development of NASICON cathode materials and put forward some suggestions. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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9 pages, 3098 KiB

Open AccessFeature PaperReview

Majority and Minority Charge Carrier Traps in n-Type 4H-SiC Studied by Junction Spectroscopy Techniques

by Ivana Capan and Tomislav Brodar

Electron. Mater. 2022, 3(1), 115-123; https://doi.org/10.3390/electronicmat3010011 - 14 Mar 2022

Cited by 9 | Viewed by 4249

Abstract

In this review, we provide an overview of the most common majority and minority charge carrier traps in n-type 4H-SiC materials. We focus on the results obtained by different applications of junction spectroscopy techniques. The basic principles behind the most common junction spectroscopy [...] Read more.

In this review, we provide an overview of the most common majority and minority charge carrier traps in n-type 4H-SiC materials. We focus on the results obtained by different applications of junction spectroscopy techniques. The basic principles behind the most common junction spectroscopy techniques are given. These techniques, namely, deep-level transient spectroscopy (DLTS), Laplace DLTS (L-DLTS), and minority carrier transient spectroscopy (MCTS), have led to recent progress in identifying and better understanding the charge carrier traps in n-type 4H-SiC materials. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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Other

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13 pages, 7280 KiB

Open AccessPerspective

On-Surface Synthesis and Applications of 2D Covalent Organic Framework Nanosheets

by Jinwei Fan, Zhuoqun Wang, Haoge Cheng, Dingguan Wang and Andrew Thye Shen Wee

Electron. Mater. 2023, 4(2), 49-61; https://doi.org/10.3390/electronicmat4020005 - 12 Apr 2023

Cited by 3 | Viewed by 3347

Abstract

Covalent organic framework nanosheets (COF nanosheets) are two-dimensional crystalline porous polymers with in-plane covalent bonds and out-of-plane Van der Waals forces. Owing to the customizable structure, chemical modification, and ultra-high porosity, COF nanosheets show many fascinating properties unique to traditional two-dimensional materials, and [...] Read more.

Covalent organic framework nanosheets (COF nanosheets) are two-dimensional crystalline porous polymers with in-plane covalent bonds and out-of-plane Van der Waals forces. Owing to the customizable structure, chemical modification, and ultra-high porosity, COF nanosheets show many fascinating properties unique to traditional two-dimensional materials, and have shown potential applications in gas separation, sensors, electronic, and optoelectronic devices. This minireview aims to illustrate recent progress on two-dimensional covalent organic framework nanosheets, from two aspects of on-surface synthesis and potential applications. We first review the synthesis of COF nanosheets at the gas–solid interface. On-surface synthesis under ultrahigh vacuum and on-surface synthesis under vapor are highlighted. In addition, we also review the liquid–solid interface synthesis of COF nanosheets at various substrates, i.e., both crystalline and amorphous substrates. Beyond the synthesis, we highlight state-of-the-art applications of the COF nanosheets, particularly in charge transport, chemical sensors, and gas separation. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials II)

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