Electronic Materials

16 pages, 1406 KB

Open AccessArticle

Monolayer and Bilayer MoS₂ Under Proton Irradiation: Electronic Stopping and Charge Capture Revealed by Real-Time TDDFT

by Ligang Wang, Guanxiang Yang, Lihongye Liao and Qiang Zhao

Electron. Mater. 2026, 7(2), 14; https://doi.org/10.3390/electronicmat7020014 - 18 Jun 2026

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Monolayer and few-layer MoS₂ are promising two-dimensional electronic materials, but proton irradiation can trigger ultrafast electronic excitation and charge transfer before defect formation. Here, real-time time-dependent density functional theory (RT-TDDFT) is used to investigate proton-induced electronic stopping and localized charge capture in [...] Read more.

Monolayer and few-layer MoS₂ are promising two-dimensional electronic materials, but proton irradiation can trigger ultrafast electronic excitation and charge transfer before defect formation. Here, real-time time-dependent density functional theory (RT-TDDFT) is used to investigate proton-induced electronic stopping and localized charge capture in monolayer and bilayer MoS₂ under normal incidence. Four impact positions are examined in monolayer MoS₂, namely, the hollow channel, the Mo–S bond center, and two trajectories close to Mo and S atoms. Under hollow channel incidence, the stopping power shows a non-monotonic dependence on proton velocity. When comparing the different trajectories, the hollow channel path gives the lowest stopping power, whereas the Mo–S bond center path gives the highest values, indicating strong sensitivity to the in-plane valence charge distribution. By contrast, the time-averaged localized captured charge decreases with increasing velocity and is generally largest for the close to Mo trajectory. Under the same hollow channel condition, the monolayer stopping power exceeds the bilayer value in the main stopping region, whereas the bilayer generally shows slightly enhanced localized charge capture. These results show that electronic stopping and localized charge capture are distinct but coupled microscopic components of proton-induced electronic response in MoS₂ and provide first-principles insight relevant to ion-beam processing and radiation-tolerant two-dimensional devices. Full article

(This article belongs to the Special Issue Emerging Trends in Electronic Materials and Functional Nanostructures)

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14 pages, 3589 KB

Open AccessArticle

Pd-Induced Electronic Activation and Strain-Tunable Adsorption-Coupled Electronic Modulation in Janus ZrSSe Monolayers

by Guanxiang Yang, Ligang Wang, Lihongye Liao, Qiang Zhao and Xiaoping Ouyang

Electron. Mater. 2026, 7(2), 13; https://doi.org/10.3390/electronicmat7020013 - 8 Jun 2026

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Abstract

Pd-decorated Janus ZrSSe monolayers provide a promising platform for adsorption-coupled electronic modulation in two-dimensional materials. Using first-principles density functional theory, we systematically investigate the structural stability, electronic properties, and adsorbate-induced electronic response of Pd-modified Janus ZrSSe. The results show that Pd is most [...] Read more.

Pd-decorated Janus ZrSSe monolayers provide a promising platform for adsorption-coupled electronic modulation in two-dimensional materials. Using first-principles density functional theory, we systematically investigate the structural stability, electronic properties, and adsorbate-induced electronic response of Pd-modified Janus ZrSSe. The results show that Pd is most stably anchored at the hollow site on the S-terminated surface, with a formation energy of

- 1.45

eV, while substitutional incorporation remains energetically unfavorable even after HSE06 refinement. Compared with pristine ZrSSe, Pd decoration markedly strengthens the interaction with adsorbates, leading to strong chemisorption for CO (

- 1.026

eV) and C₂H₂ (

- 0.748

eV), whereas H₂ remains comparatively weakly bound (

- 0.258

eV). Electronic-structure analysis reveals that CO induces the most pronounced perturbation because of strong orbital hybridization between Pd 4d states and C/O 2p states, resulting in the largest band-edge modulation among the three adsorbates. More importantly, biaxial strain provides an effective external degree of freedom for continuously tuning the electronic structure: tensile strain widens the band gap, whereas compressive strain systematically narrows it and ultimately drives a semiconductor-to-metal transition at sufficiently large compression. These findings establish Pd-decorated Janus ZrSSe as a strain-tunable electronic material in which adsorption, orbital hybridization, and band-edge evolution are intimately coupled, offering fundamental insights into controllable electronic modulation in polar two-dimensional systems. Full article

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10 pages, 2680 KB

Open AccessEditor’s ChoiceArticle

Amorphous GaO_x Thin Film-Based Optoelectronic Artificial Synapses Towards Physical Reservoir Computing

by Kotaro Takanashi, Manami Miyazaki, Iori Yamasaki, Hiroaki Komatsu, Toshiya Kounoue, Masatoshi Koyama and Takashi Ikuno

Electron. Mater. 2026, 7(2), 12; https://doi.org/10.3390/electronicmat7020012 - 6 Jun 2026

Cited by 1 | Viewed by 1034

Abstract

This study investigated the optoelectronic synaptic properties of amorphous gallium oxide (GaO_x) thin films for low-power physical reservoir computing (PRC) applications. The fabricated devices were irradiated with time series UV-C light to characterize the paired pulse facilitation (PPF) index, a fundamental [...] Read more.

This study investigated the optoelectronic synaptic properties of amorphous gallium oxide (GaO_x) thin films for low-power physical reservoir computing (PRC) applications. The fabricated devices were irradiated with time series UV-C light to characterize the paired pulse facilitation (PPF) index, a fundamental synaptic property governed by transient photocurrent dynamics. Furthermore, the short-term memory (STM) capacity and parity check (PC) nonlinearity were quantitatively evaluated as essential PRC performance metrics, alongside a practical demonstration using a handwritten digit recognition task. The experimental results revealed a high PPF index when the width and interval of the input light pulses were comparable to or shorter than the inherent photocurrent time constants of the device. Although the evaluated nonlinearity was lower than that of conventional optoelectronic artificial synapses based on other semiconductor materials, the GaO_x device exhibited a comparable short-term memory capacity. Consequently, the reservoir layer achieved a high classification accuracy of approximately 90% in the handwritten digit recognition task. As these performance metrics were higher than those of the annealed sample, the device without annealing proved to be more suitable for PRC applications. These findings indicate that the amorphous GaO_x thin film device holds significant potential to serve as a robust, UV-C-responsive edge artificial intelligence (AI) sensor in harsh environments, such as outer space. Full article

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12 pages, 20710 KB

Open AccessArticle

In Situ Coating Thickness Measurement of Parylene Using a Capacitive Sensor

by Manuel Seidenath, Daniel Jäger, Jochen Wilhelm, Hubert Rauh and Martin Maerz

Electron. Mater. 2026, 7(2), 11; https://doi.org/10.3390/electronicmat7020011 - 2 Jun 2026

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Abstract

With parylene coatings, conventional layer thickness measurement methods such as gravimetry, reflectometry, and cross-sectional microscopy are performed post-process and do not allow real-time monitoring or control. This paper presents a novel in situ measurement method based on the capacitance change in interdigitated copper [...] Read more.

With parylene coatings, conventional layer thickness measurement methods such as gravimetry, reflectometry, and cross-sectional microscopy are performed post-process and do not allow real-time monitoring or control. This paper presents a novel in situ measurement method based on the capacitance change in interdigitated copper electrodes fabricated on a printed circuit board (PCB). As parylene deposits on this sensor, the effective permittivity above the electrodes increases from

ϵ_{r} \approx 1

(vacuum) to

ϵ_{r} = 2.1 – 3.2

(parylene), causing a measurable capacitance change. Finite element simulations were performed to model the relationship between layer thickness and sensor capacitance. Experimental validation with parylene C and F-VT4 demonstrated good agreement between simulation and measurement. Four consecutive parylene C runs with 60 g raw material showed reproducible capacitance increases of 49–53 pF, corresponding to layer thicknesses of 20–25 µm, verified by cross-sectional microscopy. Two coating runs were performed with parylene F-VT4 with target layer thicknesses of 2.5 µm and 5 µm. They show particularly good agreement with the simulation. The proposed method enables real-time process monitoring and provides a foundation for closed-loop control of parylene CVD processes. Full article

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15 pages, 43724 KB

Open AccessArticle

Study on the Effect of Annealing on Ga₂O₃ Thin Films Deposited on Silicon by RF Sputtering

by Ana Sofia Sousa, Duarte M. Esteves, Tiago T. Robalo, Mário S. Rodrigues, Katharina Lorenz and Marco Peres

Electron. Mater. 2026, 7(2), 10; https://doi.org/10.3390/electronicmat7020010 - 26 May 2026

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Abstract

Gallium oxide is an ultra-wide bandgap semiconductor with excellent opto-electronic properties, making it a highly promising material for a wide range of applications and devices. In this article, we report how the optical, morphological, structural, and compositional properties of

β

-Ga₂O [...] Read more.

Gallium oxide is an ultra-wide bandgap semiconductor with excellent opto-electronic properties, making it a highly promising material for a wide range of applications and devices. In this article, we report how the optical, morphological, structural, and compositional properties of

β

-Ga₂O₃ thin films deposited by RF Sputtering on silicon substrates are affected by thermal treatments. Ellipsometric spectra recorded at multiple angles of incidence from several samples subjected to thermal annealing in the range of 550–1000 °C were analyzed to extract the optical functions using appropriate multilayer models. This analysis is complemented by compositional, structural, and morphological characterization techniques. We observed two main stages of crystallization with increasing annealing temperature; up to 700 °C, there is an increase in density and then, for 700–1000 °C, there is an improvement in crystallinity. While the refractive index increases continuously throughout this process, we found that the polarizability of the samples decreases in the first stage and increases in the second. These observations demonstrate that thermal treatments are a powerful tool to tune the optical properties of Ga₂O₃ thin films for device applications. Full article

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7 pages, 1857 KB

Open AccessEditor’s ChoiceCommunication

Room-Temperature Operation of an Injection-Type Ballistic Rectifier on Bilayer Graphene

by Ihor Petrov and Ulrich Kunze

Electron. Mater. 2026, 7(2), 9; https://doi.org/10.3390/electronicmat7020009 - 8 May 2026

Viewed by 1816

Abstract

This work investigates the performance improvement of a four-probe ballistic rectifier on bilayer graphene (BLG) through the formation of an energy gap under a perpendicular electric field. For this purpose, exfoliated BLG was deposited on oxidized n⁺-Si and structured into an [...] Read more.

This work investigates the performance improvement of a four-probe ballistic rectifier on bilayer graphene (BLG) through the formation of an energy gap under a perpendicular electric field. For this purpose, exfoliated BLG was deposited on oxidized n⁺-Si and structured into an asymmetric cross junction with 90 nm wide channels. The junction consists of a straight voltage stem (contacts U, L) and slanted current injectors (contacts 1, 2). The differential conductance of the stem, g_UL, as a function of back-gate bias, V_BG, reveals clear indications of energy gap formation and lateral depletion zones at the edges of the channel. The DC characteristic of the ballistic rectifier, V_UL(I₁₂), shows an increase in the output voltage V_UL with increasing V_BG. We attribute this to reduced diffuse scattering at the rough edges when the lateral depletion zones form smooth barriers. Full article

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21 pages, 1821 KB

Open AccessReview

Tactile and Visual Artificial Synaptic Devices: Progress and Challenges

by Zhifeng Chen, Chengying Chen and Yufei Huang

Electron. Mater. 2026, 7(2), 8; https://doi.org/10.3390/electronicmat7020008 - 15 Apr 2026

Cited by 1 | Viewed by 1409

Abstract

The von Neumann architecture faces a “memory wall” problem due to the physical separation of memory and processor, posing major challenges to energy efficiency and latency in the era of artificial intelligence. To overcome these bottlenecks, artificial synaptic devices inspired by biological systems [...] Read more.

The von Neumann architecture faces a “memory wall” problem due to the physical separation of memory and processor, posing major challenges to energy efficiency and latency in the era of artificial intelligence. To overcome these bottlenecks, artificial synaptic devices inspired by biological systems have emerged as an important research direction. By integrating sensing and computing functions at the device level, these architectures provide a promising approach for the efficient processing of natural physical signals. Supported by advances in functional materials and artificial neural network (ANN) algorithms, artificial synaptic devices are capable of perceiving and processing various external stimuli, showing strong potential for applications in intelligent electronic skins, robotics, and edge computing. This review provides a comprehensive overview of recent advances in artificial synaptic devices, with particular emphasis on tactile and visual sensing applications. We discuss representative device types and operating mechanisms, analyze critical challenges from the perspectives of material engineering and functional integration, and further summarize potential solutions and future trends toward multimodal sensory–memory–computing systems. Full article

(This article belongs to the Special Issue Emerging Trends in Electronic Materials and Functional Nanostructures)

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12 pages, 1664 KB

Open AccessEditor’s ChoiceArticle

In Situ Compositing-Induced Matrix Planarization for Enhanced Thermoelectric Properties of β-Cu₂Se/SnSe Composites

by Zhonghe Zhu, Changcun Li, Haibo Wang, Yvcui Sun, Jing Qiao, Mingqian Hao, Wei Zhao and Degang Zhao

Electron. Mater. 2026, 7(2), 7; https://doi.org/10.3390/electronicmat7020007 - 9 Apr 2026

Viewed by 980

Abstract

With the intensification of the energy crisis and environmental issues, thermoelectric conversion technology has become a research focus due to its ability to directly convert thermal and electrical energy. β-Cu₂Se thermoelectric materials have garnered considerable attention owing to their distinctive physical [...] Read more.

With the intensification of the energy crisis and environmental issues, thermoelectric conversion technology has become a research focus due to its ability to directly convert thermal and electrical energy. β-Cu₂Se thermoelectric materials have garnered considerable attention owing to their distinctive physical and chemical characteristics. However, their practical implementation is hindered by the inherent imbalance between electrical and thermal transport properties. In this work, β-Cu₂Se/SnSe composite thermoelectric materials were successfully synthesized via a facile and scalable in situ compositing strategy by introducing SnSe micro-flakes as the secondary phase. The results demonstrate that the introduced SnSe secondary phase effectively modulates the carrier concentration and enhances the density-of-states effective mass through the energy filtering effect and resonant energy level regulation, thereby significantly optimizing the electrical transport properties. Meanwhile, the abundant heterointerfaces formed between the β-Cu₂Se matrix and introduced SnSe secondary phase induce intense phonon scattering, which efficiently suppresses the lattice thermal conductivity of the β-Cu₂Se/SnSe composites. Benefiting from the synergistic optimization of electrical and thermal transport behaviors, the β-Cu₂Se/5 mol% SnSe composite sample achieves a maximum figure of merit (ZT) value of ~0.51 at 750 K, which represents a 70% enhancement compared with the pristine β-Cu₂Se and a 60% improvement compared with the direct composite sample. This study provides a simple and effective in situ composite strategy for designing and synthesizing high-performance thermoelectric materials. Full article

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Electron. Mater., Volume 7, Issue 2 (June 2026) – 8 articles

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