bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atomic Layer Deposition of Noble Metal Single Atoms and Nanoparticles for Electrocatalytic Applications
Authors: Macak Jan M. , Bawab Bilal , Rodriguez Pereira Jhonatan , Zazpe Raul 
Published: December 2024

Platinum group metals such as Pt, Ru, Pd, Ir, etc., have superior performance for various catalytic applications [1]. Due to their scarcity, efforts were being made to reduce the mass/loading or replace these noble metals. Atomic Layer Deposition (ALD) is one among the best technique to facilitate lowering of loading mass on a support of interest [2,3]. Due to the governing surface energy variations between noble metals and support surfaces, the growth initiates as nanoparticles (NP) and with a further increase in ALD cycles the agglomeration among NP’s dominates over the individual NP size increase, thus developing thin films of relatively higher thickness.
For electrocatalytic applications, it is important to choose the right substrates. Among available substrates, carbon papers and titania nanotube layers are best choices considering their physio-chemical properties, availability and low costs incurred.
The uniform decoration of these substrates by NPs of catalysts proved to be highly efficient in electrocatalysis, as shown in our recent papers [3-6].
The presentation will introduce and describe the synthesis of different noble metal NPs by ALD on important substrates. It will also include the corresponding physical and electrochemical characterization and encouraging results obtained in electrocatalysis.
References:
[1] Huang, Z. F. et al. Advanced Energy Materials vol. 7 (2017) 1700544.
[2] Yoo, J. E. et al. Electrochem. commun. 86 (2018) 6
[3] Anitha, V. C. et al. J. Catal. 365 (2018) 86.
[4] Sitaramanjaneya M. Thalluri & Macak, J. M. Small 19 (2023) 2300974.
[5] Bawab, B. & Macak, J. M., et al., Electrochim. Acta 429 (2022) 141044
[6] Bawab, B. & Macak, J. M., et al., Chem. Eng. Journal 482 (2024) 148959
(Invited) Development of High-Bandwidth GaN-Based Micro-LEDs for Visible Light Communication
Authors: Tian Pengfei , Zhang Zhen , Jin Zuxin , Lin Runze 
Published: December 2024

With the expectation of extremely high-capacity requirement of 6G networks, visible light communication (VLC) has abundant frequency resource and excellent performance in 6G integrated communication in space, air, underwater, indoor, and car networks [1]. The micro light emitting diode (micro-LED) is regarded as a reliable light source for high-speed VLC and is capable of illumination while providing communication. Compared to the traditional light source, micro-LED possesses better characteristics such as high bandwidth, low power consumption, long lifetime and high reliability [2-3].
In this work, we made improvements in the micro-LED fabrication compared with the common negative doped GaN (common-n) devices we produced by shallow etching before [4]. Micro-LEDs can be manufactured into completely separate pixels for independent control by deep etching. For green micro-LEDs with a wavelength of 510nm, the light output power of deep etching one increased. At the same working current density, the -3dB bandwidth of deep etching micro-LED has an average growth of 50% compared to shallow etching one. Benefit from the promotion of optical power and -3dB bandwidth, micro-LED with independent etching structure have a better performance in VLC system. A record date rate of 6.58Gpbs was achieved by single green micro-LED employing the orthogonal frequency division multiplexing (OFDM) modulation scheme, which proposes a feasible optimization direction for the integration of micro-LED high-speed VLC and lighting.

REFERENCES:

[1] Chi N, Zhou Y, Wei Y, et al. Visible light communication in 6G: Advances, challenges, and prospects[J]. IEEE Vehicular Technology Magazine, 2020, 15(4): 93-102.
[2] James Singh K, Huang Y M, Ahmed T, et al. Micro-LED as a promising candidate for high-speed visible light communication[J]. Applied Sciences, 2020, 10(20): 7384.
[3] Lin R, Jin Z, Qiu P, et al. High bandwidth series-biased green micro-LED array toward 6 Gbps visible light communication[J]. Optics Letters, 2022, 47(13): 3343-3346.
[4] Zhu S, Qiu P, Shan X, et al. Micro-LED based double-sided emission display and cross-medium communication[J]. IEEE Photonics Journal, 2022, 14(3): 1-5.

Figure 1
Effect of Polymer Type Additives in Selective Wet Etching of Si1-XGex- to Si-Film to Enhance Etch Rate Selectivity
Authors: Lee Changjin , Lee Ji-Eun , Jang Eun-Woo , Kim Ji-Hoon , Park Jinsub , Park Jea-Gun 
Published: December 2024

To extend the scalability of the logic transistor beyond the 3-nm process, the architecture of the metal-oxide-semiconductor field-effect transistor (MOSFET) has changed from FinFET to gate-all-around FET (GAAFET). In addition, to continue the scaling of MOSFET further, various concepts of nanosheet architecture devices, including GAAFET, Forksheet FET, and Complementary FET, have been vigorously researched. To fabricate nanosheet devices, releasing Si channels via selective etching of Si1-xGex- to Si-layer is a key process. However, during the selective etching of Si1-xGex- to Si-layer, simultaneous etching of Si- with Si1-xGex-layer is inevitable. Therefore, protecting the Si-layer while selective etching of the Si1-xGex-layer is a major challenge to acquire uniform channel layers (i.e., Si-layers).
In this study, to protect the Si-layer during the selective wet etching of Si1-xGex- to Si-film, we came up with an idea based on the concept of selective chemisorption of polymers on Si- rather on Si1-xGex-film. Functional groups of polymers can chemisorb onto the Si surface, followed by building the hindrance layer that prohibits the etching of Si-film. Thus, we tested the effect of polymer type additives in selective wet etching of Si1-xGex- to Si-film depending on the functional groups (carboxylic group, amine group, alcohol group, etc.) and the molecular weight. To characterize the etching amount of the Si-film during the selective wet etching of Si1-xGex- to Si-film, the wet etching of epitaxially grown 3-periods of Si1-xGex/Si multilayer on Si substrate was performed followed by high-resolution transmission electron microscopy (HR-TEM) analysis. When using a specific type of polymer additive during wet etching, the etching amount of Si-film was >0.5 nm within 2 minutes, while that using without any additive was ~0.8 nm within 2 minutes, indicating that polymer type additive can produce the hindrance layer successfully onto Si-film preventing the etching of Si-film. The HR-TEM images depending on polymer types and mechanism of protecting Si-film during the selective wet etching of Si1-xGex- to Si-film will be presented in detail.

Acknowledgement

This work was supported by the Technology Innovation Program (20022475, Development of wet Etchant capable of high selection etching in microprocesses below 10 nm) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea)

References

[1] Lee, Seung-Jae, et al. "Extremely high selective Si1−xGex-film wet etchant generating highly dissolved oxygen via peracetic acid oxidant for lateral gate-all-around FETs with a logic node of less than 3-nm." Chemical Engineering Journal 475 (2023): 146257.
(Invited) Graded Index Silicon Germanium Photonics Circuits in the Mid-Infrared
Authors: Turpaud Victor , Nguyen Thi Hao Nhi , Bricout Annabelle , Dely Hamza , Frigerio Jacopo , Calcaterra Stefano , Hartmann Jean-Michel , Coudevylle Jean-René , Villebasse Cedric , Bouville David , Alonso-Ramos Carlos , Vivien Laurent , Isella Giovanni , Marris-Morini Delphine 
Published: December 2024

Mid-infrared (mid-IR) spectroscopy can be used to identify chemical and biological substances. Indeed, most molecules absorb light at specific wavelengths in the mid-infrared (mid-IR). Mid-IR photonic circuits on silicon chips have recently gained a lot of attention. Indeed, they can provide high-performance with a low power consumption, while being cheap, compact, and light. Germanium (Ge) and silicon-germanium (SiGe) alloys with a high Ge concentration are particularly interesting because of the wide transparency window of Ge extending up to 15 µm. It has been demonstrated for a few years now that a Ge-rich graded SiGe platform relying on a graded SiGe layer epitaxially grown on a Si substrate can be used as a photonics platform for mid-IR operation in a wide spectral range.
In this invited talk, recent developments concerning graded SiGe photonic integrated circuits will be presented. First, passive devices will be reviewed. It will be shown that graded-SiGe waveguides can be used in an unprecedented spectral range, e.g. up to 11 µm. Mach Zehnder interferometers, resonators and integrated Fourier transform spectrometers will be discussed. Then, a large bandwidth light source based on non-linear optical effects in SiGe waveguides [1] will be presented, together with results on integrated mid-IR optoelectronic modulators [2, 3]. Tunable electro-optical frequency-comb generation around 8 µm wavelength based on such integrated modulators will also be discussed [4]. Finally, the recent scale-up of this platform will be shown, with the first demonstration of low-loss mid-infrared waveguides fabricated on a Ge-rich SiGe strain-relaxed buffer grown on an industrial-scale 200 mm wafer [5].
Acknowledgment:
This work was co-funded by ANR Light-up Project (ANR-19-CE24-0002-01) and by European Union (ERC, Electrophot,101097569). This work was partly supported by the French RENATECH network.
References:
[1] M. Montesinos-Ballester, et al, ACS Photonics, 7, 3423-3429, (2020).
[2] T.H.N. Nguyen, et al, Optics Express, 30, (26), 47093 (2022).
[3] T.H.N. Nguyen, et al, Advanced Photonics Research, 2200237 (2022).
[4] V. Turpaud, et al, Laser & Photonics Reviews, 2300961 (2024).
[5] V. Turpaud, et al, to be published, 2024.
Foundational Machine Learning Interatomic Potential to Study Li-Ion Battery Cathode Phase Transformation with Charge Transfer
Authors: Deng Bowen , Zhong Peichen , Jun KyuJung , Riebesell Janosh , Han Kevin , Bartel Christopher J. , Ceder Gerbrand 
Published: December 2024

Large-scale simulations with complex electron interactions remain one of the greatest challenges for atomistic modeling of electrochemical systems. Our recent work, Crystal Hamiltonian Graph Neural Network (CHGNet), presents foundational graph-neural-network-based machine-learning interatomic potential (MLIP). The inclusion of charge information by magnetic moment prediction enables CHGNet to better describe both atomic and electronic degrees of freedom, which opens the possibility for a better understanding of electron-redox coupled behaviors that are essential for applications such as battery cathode materials for energy storage.
We demonstrate the use of CHGNet MLIP in electrochemistry by modeling in detail the process by which orthorhombic LixMnO2 transforms to a spinel-like structure. This transformation is facilitated by the valence-dependent Mn migration and charge disproportionation which can only be modeled accurately with an MLIP that captures the very different chemical behavior of transition metals’ different valence states. Moreover, we show the Mn-rich disordered rocksalts (DRX) exhibit similar phase transformation to a spinel-like phase, leading to improved capacity and Li-ion transport kinetics. Our study demonstrates critical atomic-level insights into Li-ion cathode electrochemistry, which became possible with charge-informed long-time simulations at scale enabled by modern AI methods.
Development of a Highly Selective Etching Process for SiO2 over Si and SiNx Using F/H-Based Remote Plasmas and a Vapor Phase Solvent
Authors: Lee Ji Yeon , Gil Hong Seong , Park Woo Chang , Jang Yun Jong , Kim Dong Woo , Yeom Geun Young 
Published: December 2024

Isotropic etching is traditionally performed using liquid-based wet etching techniques. However, with the increasing integration of devices, achieving conformal etching in high aspect ratio patterns becomes difficult, as liquid chemicals are limited in their ability to penetrate deep into these structures. Moreover, during the drying phase following chemical treatment, surface tension can lead to pattern collapse. Consequently, there is a growing need for dry isotropic etching methods to replace conventional wet etching in advanced device manufacturing.
In cases where high selectivity for SiO2 isotropic dry etching is required, mixtures of fluorine-based and hydrogen-based gases are typically used to generate HF, which acts as the etchant for SiO2. SiO2 can be etched through two main mechanisms. The first mechanism involves the direct reaction of HF with H2O or alcohol to etch SiO2. The second mechanism involves the formation of (NH4)2SiF6 salt through the reaction of HF with NH3, which occurs in a plasma containing NH3 and NF3. This (NH4)2SiF6 salt is then sublimated and removed in a subsequent heating process at temperatures above 100°C.
The reaction of HF with NH3 to form (NH4)2SiF6 can lead to the generation of ammonium salts that may act as contaminants within the etching chamber. Additionally, this approach necessitates an extra thermal treatment step to eliminate the (NH4)2SiF6 salt. HF can be supplied either directly as vapor or generated through plasma containing fluorine and hydrogen. Plasma-based methods generally offer advantages in terms of safety and process efficiency compared to direct HF vapor usage
In this study, we investigated an isotropic dry etching process in which HF etchant is generated by discharging fluorine-based and hydrogen-based gas mixtures. A vapor-phase solvent is supplied outside the discharge region to ionize HF and directly etch SiO2. When using H2O vapor as the solvent, we achieved the etch selectivity of SiO2 over SiNx and poly Si higher than 100 and 600, respectively, was obtained while having SiO2 EPC of ~30 nm/min by optimized conditions. The etching mechanism was clarified through gas-phase and surface analyses using optical emission spectroscopy (OES), quadrupole mass spectrometry (QMS), and X-ray photoelectron spectroscopy (XPS). To assess pattern collapse, we compared the wet phase and vapor phase processes applied to the Si trench pattern. The results suggest that using fluorine and hydrogen-based remote plasmas with a vapor-phase solvent is promising for highly selective isotropic SiO2 etching in the fabrication of next-generation 3D devices.
Investigation of the Impact of Different Electrode Inhomogeneities on the Voltage Response of Li-Ion Batteries
Authors: Dubarry Matthieu , Beck David 
Published: December 2024

Battery degradation is a fundamental concern in battery research, with the biggest challenge being to maintain performance and safety upon usage. From the microstructure of the materials to the design of the electrodes and their assembly in cells, it is impossible to achieve perfect reproducibility. This is problematic because small manufacturing or local variations could have big repercussions on performance and reliability.
In this purely theoretical study, we investigated the potential impact of different inhomogeneities on the performance on two typical Li-ion batteries with a graphite negative electrode and either nickel manganese cobalt oxide 111 or lithium iron phosphate as the positive electrode. Our modeling results showed that out of the nine considered inhomogeneities, only three could affect performance, when at a mild level and randomly distributed, with two unlikely to happen in real cells because they would probably disappear during rest. The only one found to be impactful was inhomogeneities of resistance on the negative electrode. In that case, we predicted an impact on the voltage response that is close to the signature that was attributed to inhomogeneities in the literature. Moreover, such inhomogeneities also open the possibility of a snowball effect as it was shown to induce lithiation inhomogeneities at end of charge when the PE is limiting while the NE in the middle of a well define voltage plateau.
Our study showed that it is necessary to assess the level at which the paralleling is occurring, electrode or full cell, as the model predicts an impact on how much current is flowing within or in-between the electrodes.
While we are well aware of the limitations of this work, we believe it provides a good starting point for discussion with the community.
High-Mobility Indium Oxide Thin Film Transistors with High Reliability
Authors: Ghediya Prashant , Magari Yusaku , Sadahira Hikaru , Endo Takashi , Furuta Mamoru , Zhang Yuqiao , Matsuo Yasutaka , Ohta Hiromichi 
Published: December 2024

Transparent oxide semiconductors (TOSs) based thin-film transistors (TFTs) that exhibit higher field effect mobility (μ
FE) are highly required toward the realization of next-generation displays. Among numerous types of TOS-TFTs, In2O3-based TFTs are the front-running candidate because they exhibit the highest μ
FE ~100 cm2 V−1 s−1. However, the device operation of In2O3 TFTs is unreliable; a large voltage shift occurs especially when negative gate bias is applied due to adsorption/desorption of gas molecules. Although passivation of the TFTs is used to overcome such instability, previously proposed passivation materials did not improve the reliability. Here, we show that the In2O3 TFTs passivated with Y2O3 and Er2O3 films are highly reliable and do not show threshold voltage shifts when applying gate bias. We applied positive and negative gate bias to the In2O3 TFTs passivated with various insulating oxides and found that only the In2O3 TFTs passivated with Y2O3 and Er2O3 films did not exhibit threshold voltage shifts. We observed that only the Y2O3 grew heteroepitaxially on the In2O3 crystal. This would be the origin of the high reliability of the In2O3 TFTs passivated with Y2O3 and Er2O3 films. This finding accelerates the development of next-generation displays using high-mobility In2O3 TFTs.
Reference: P. R. Ghediya, Y. Magari*, H. Sadahira, T. Endo, M. Furuta, Y. Zhang, Y. Matsuo, and H. Ohta*, Preprint at <http://arxiv.org/abs/2404.03856> (2024).
(Invited) Integration and Optimization of 2D Transition Metal Dichalcogenides as Switching Layers in Memristors
Authors: Capasso Andrea 
Published: December 2024

Memristive devices possess the ability to dynamically adjust resistance based on previous voltage and current inputs. They represent a frontier in next-generation computational hardware, offering unparalleled potential for brain-inspired computing and neuromorphic engineering. Among the various configurations, electrochemical metallization (ECM) memristors feature a solid electrolyte layer sandwiched between two electrodes and perform resistive switching via filament formation (SET) and dissolution (RESET) [1]. Recent studies have focused on the integration of two-dimensional (2D) materials into the design of ECM memristors, aiming at improving performance and unlocking new functionalities [2-4]. 2D transition metal dichalcogenides and hexagonal boron nitride, in particular, are promising candidates for realizing memristors with ultra-low switching voltages, suitable for neuromorphic computing and artificial synapses [5, 6].
In this talk, I will focus on vertical ECM memristor in crossbar configuration using chemical vapor deposited (CVD), atomic-thick MoSe2 as switching material, and Au/Cu as bottom/top electrodes. The devices exhibit nonvolatility and bipolar resistive switching behavior, with well-defined SET/RESET voltages (below 1V in absolute value) [7]. We performed atomic-scale investigations by transmission electron microscopy to unveil the filament formation mechanism within the MoSe2 layer. Our results shed light on the Cu/MoSe2 interface, particularly critical for memristor performance, providing key information on the intermixing and diffusion mechanisms of Cu atoms within the device structure.
Furthermore, we studied the effect of XeF2 fluorination of the MoSe2 films to tune their surface properties and improve the ion transport kinetics across the interface with Cu. By carefully controlling the XeF2 process, we were able to induce structural and chemical modifications in the MoSe2, such as layer thinning and doping/implantation. This could provide a way of controlling the interface morphology and ultimately the performance and reliability of the memristive devices. Transport properties and X-ray photoelectron spectroscopy analyses provided insights into the fluorination-induced modifications on the MoSe2 surface, offering a framework for performance optimization. Overall, these findings rationalize the 2D materials-based ECM memristor operation and highlight the potential for advanced applications.

References

[1] I. Valov et al., Nanotechnol., 22, 289502, 2011.
[2] R. Xu et al., Nano Lett., 19, 2411–2417, 2019.
[3] J. Jian et al., Adv. Electron. Mater., 8, 2022.
[4] Y. Shi et al., Nat. Electron., 1, 458–465, 2018.
[5] W. Huh et al., Adv. Mater., 32, 2002092, 2020.
[6] G. Cao et al., Adv. Funct. Mater., 31, 2005443, 2021.
[7] J. Fernandes et al., ACS Appl. Mater. Interfaces, 16, 1767–1778, 2024.
Periodically Strained 2D Materials for Tunable Optoelectronic Applications
Authors: McLean Mitchel , Nguyen Anh Tuan , Lee Woochul , Gaillard Nicolas 
Published: December 2024

An expansion in the domain of thin and flexible electronics has led to advances in strain engineering, and particularly strain induced in atomically flat two-dimensional (2D) semiconductors. An array of physical properties has been shown to be modified through strain in 2D materials, including but not limited to carrier mobility, band gap energy, and band gap type. Due to their large aspect ratio, strain can be imparted both macroscopically (“long-range strain”) as well as at the nanoscale (“short-range strain”). Periodic short-range strain allows for band gap modulation which modifies the local optical absorption spectrum over the 2D material. The overarching goal of this work is the characterization of such strained 2D systems using patterned metallic layers to induce periodic optoelectronic properties.
In this communication, we report on our progress in producing patterned metal (Au, Ag) and metal-oxide substrates which serve as a basis for imparting periodic short-range strain in 2D materials (MoS2, MoSe2). The synthesis of these substrates is accomplished by first creating a metal pattern on a silicon dioxide/silicon substrate using a combination of lithography, laser ablation, and/or deposition processes, followed by an annealing process which results in nanometer-scale hemispherical islands that are then used as a support for suspended, strained 2D semiconductors. We employ a variety of characterization techniques to study the structural and electrical properties of the systems, including Raman spectroscopy, atomic force microscopy (AFM), conductive AFM, Kelvin probe force microscopy, and scanning electron microscopy. We aim to compare experimental optoelectronic data with results from a density functional theory strain model calculated using topographic information as input parameters.