bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stepwise Growth of Crystalline MoS2 in Atomic Layer Deposition
Authors: Cho Ah-Jin , Ryu Seung Ho , Kim Seong Keun 
Published: February 2024

Transition metal dichalcogenides (TMDCs) are layered materials in which each layer is weakly bound by van der Waals forces. TMDCs have interesting intrinsic properties, including high mobility and excellent electrostatic controllability, even at monolayer thickness. Hence, they have emerged as promising materials for widespread applications in nanoelectronics, optoelectronics, gas sensors, etc. The aforementioned properties of TMDCs are significantly affected by the structural
quality and crystallinity. Accordingly, scalable techniques have been sought for synthesizing well-crystallized TMDCs.
Atomic layer deposition (ALD) is considered a promising growth technique for transition metal dichalcogenides (TMDCs) because it ensures uniformity and homogeneity of the TMDC grains. However, the poor crystallinity of ALD-grown TMDCs remains a critical challenge. Although crystallinity depends on the growth mechanism, the growth behavior of crystalline TMDCs in ALD is unclear. We investigated the growth behavior of highly crystallized molybdenum disulfide (MoS2) by ALD at 650 oC with an extra pulse of remote H2 plasma. Growth at high temperatures using the activated species aided surface diffusion of the adsorbates. The ALD process facilitates repeated growth and saturation of MoS2, unlike the normal ALD of 3D bulk materials, where the film thickness monotonically increases with the number of ALD cycles. This unique behavior resulted from the evolution of the basal plane without dangling bonds. On the basal plane, MoS2 lateral growth dominates vertical growth, and prolonged incubation is required for nucleation on the basal plane. The grain size is small (up to two monolayers) because of the limited mobility on SiO2, and the grains of the third layer grow to a few hundred nanometers. These findings provide insights into the development of ALD technology for application to high-quality TMDCs.
Solution ALD Processing of Halide Perovskite Thin Films Yields Superior Functional Quality and Stability Than Classical Processing
Authors: Koch Vanessa , Barr Maissa K. S. , Büttner Pascal , Bär Marcus , Brabec Christoph , Bachmann Julien 
Published: February 2024

The range of materials accessible by classical ALD is limited by the volatility requirement applied to the precursors. However, solution ALD (sALD) transfers the self-limiting surface reaction principle of ALD into the solution processing realm and allows for the same level of control in the deposition of ionic or molecular solids, such as polymers, metal-organic frameworks, and halide perovskites, which cannot be delivered from the gas phase.
We have developed an sALD procedure for the direct deposition of the prototypical halide perovskite compound, methylammonium triiodoplumbate(IV), (H3CNH3)(PbI3), also referred to as methylammonium lead iodide or MAPI. The process saturates upon dosage variation to a self-limiting growth rate. The material is obtained in crystalline and highly pure, stoichiometric form at room temperature. All analytical techniques confer to indicate the absence of any lead iodide trace. The MAPI layers generated by sALD can be integrated into planar heterojunction stacks and yield functional solar cells.
The direct comparison of films of several thickness values prepared in pairs by sALD and by a state-of-the-art spin-coating method shows that the sALD films always overperform their spin-coated counterparts both in terms of charge carrier lifetimes and in terms of stability towards decomposition under thermal, radiative or vacuum stress.
Thus, experimental atomic-level control of solution-processed semiconductors is accessible for the first time. It can now be applied to the accurate investigation of halide perovskite photophysics and photochemistry fundamentals as they pertain to transport and interface phenomena.
Stabilized Positive Electrode Material to Enable High Energy/Power Density Lithium-Ion Batteries
Authors: Ahaliabadeh Zahra , Miikkulainen Ville , Mäntymäki Miia , Kallio Tanja 
Published: February 2024

Recently, the large-scale deployment of electric vehicles (EVs) and stationary battery systems has put
forward urgent requests for rechargeable batteries with higher energy/power density and longer
lifespans. As such, next-generation Li-ion batteries (LiBs) are expected to meet these requirements. The
possibility of using Ni-rich high-capacity cathode materials (NMC) can help to achieve that goal, however,
they still suffer from significant capacity fade via several chemical and mechanical degradation modes.
One is crack formation within secondary particles which leads to parasitic reactions that evolve oxygen
and potentially initiate the formation of inactive crystal structures. LiBs mechanical and chemical
degradation mechanisms can be extended by applying protective coatings to the cathode’s surface. Many
studies explore atomic layer deposition (ALD) for this purpose. However, the complementary molecular
layer deposition (MLD) technique might offer the benefit of depositing flexible hybrid coatings that can
accommodate potential volume changes of the electrode during the battery cycling. This study reports
the deposition of novel organic-inorganic films via the ALD-MLD method. Characterization analysis such
as FTIR, XPS, SEM-EDS, and TEM confirmed the film deposition on the surface of the NMC electrode.
Besides, the electrochemical results showed the enhancement of the coated electrode, as evidenced by
providing a longer life with a 93% capacity retention after 150 cycles (3.0-4.4 V vs. Li/Li+), while the
uncoated one retained only 83% of its initial capacity. Moreover, in situ dilatometry showed irreversible
volume change for uncoated NMC while it was mostly reversible for coated ones during the cycling. It
revealed the dilation behavior of the electrode, resulting in crack formation, which is significantly
suppressed for the coated samples. Stable cycling of Ni-rich cathode materials in crucial conditions such
as high voltage windows and elevated temperatures is still extremely challenging. To evaluate this, in situ
dilatometry was performed at elevated temperatures (40 °C and 55 °C) and higher voltage ranges (3.0-4.6
V). The results confirmed that in both conditions, the dilation behavior of the coated sample is still under
control while the capacity is comparable to the uncoated sample. This revealed that the coatings present
good lithium-ion kinetics and reduce electrolyte decomposition. Overall, this work showed the liability of
the ALD-MLD films deposited on NMC electrodes to mitigate the degradation mechanisms and provides
insight into a method that seems promising as a protective and elastic coating for future high-energy
lithium-ion battery cathodes.

Figure 1
Atomic Layer Deposition of LixCoyOz Cathodic Thin Films for Li-Ion Batteries
Authors: Peisert Antoine , Adjeroud Noureddine , Lenoble Damien , Lamblin Guillaume 
Published: February 2024

Atomic-Layer Deposition (ALD) is an appealing gas-phase technique for the deposition of thin solid cathodic films for 2D and especially 3D Li-ion microbatteries (Li-ion MBs). ALD relies on surface chemistry reactions and allows the fabrication of ultrathin pinhole free solid films with well controlled thickness, continuity and conformality. It has been shown to successfully cover 3D complex shapes for various applications including Li-ion MBs. Yet, a fairly low amount of work has been published on the realization by ALD of such cathodic active thin films. Typical cathodic materials are at least ternary compounds (including Lithium) which call for supercycles or multilayers approaches to synthesize them by ALD. As reminded for example by Maximov M. et al
1, the use of lithiated precursors complexifies the ALD fabrication due to, among others, Lithium high diffusivity and reactivity. In the case of LiCoO2 ALD synthesis for example, the only reported work to date is the one of Donders et al.
2 where the authors used CoCp2/LiOtBu as Cobalt/Lithium precursors respectively and O2 plasma as the oxidizing agent.
The talk will describe the synthesis and characterizations of the LixCoyOzthin filmspreparedby a thermal ALD approach. It will detail the supercycle methods used as well as some of the investigations performed to explore the chemistry of the deposited films (Raman spectroscopy, X-Ray Photoelectron Spectroscopy, X-Ray Diffraction and Energy Dispersive X-Ray). The electrochemical performances of the films will also be shared and compared with the State of the art.

1 Maximov, M.; Nazarov, D.; Rumyantsev, A.; Koshtyal, Y.; Ezhov, I.; Mitrofanov, I.; Kim, A.; Medvedev, O.; Popovich, A. Atomic Layer Deposition of Lithium–Nickel–Silicon Oxide Cathode Material for Thin-Film Lithium-Ion Batteries. Energies
2020, 13, 2345.

2 Donders, M. E., ArnoldBik, W. M., Knoops, H. C. M., Kessels, W. M. M., & Notten, P. H. L. (2013). Atomic layer deposition of LiCoO2 thin film electrodes for all-solid-state Li-ion micro-batteries. Journal of the Electrochemical Society, 160(5), A3066-A3071.
(Invited) Exploring New ALD Processes for Coinage and Transition Metals through Molecularly Engineered Precursors
Authors: Devi Anjana 
Published: February 2024

Atomic layer deposition (ALD) of functional materials has gained significant interest during the recent years and a range of new materials has been introduced into semiconducting manufacturing since ‘materials-limited device scaling’ has replaced the days of ‘happy geometric scaling’. The ability to integrate very thin layers into silicon structures has opened the way for a variety of novel applications which enhances the functionality and flexibility for future nanotechnologies. For ALD, precursors are indispensable and there are continuous efforts to develop new or precursors with improved physico-chemical properties.
From the precursor engineering point of view, the concept is not only to synthesize one or more arbitrary members of a particular family of ligands, rather rationally introduce distinct changes in the ligand sphere in a systematic manner. This approach provides knowledge on the relationship between the molecular structure of the precursors, their thermal characteristics and reactivity. This presentation reveals how key precursor design parameters strongly influence the efficacy of ALD by comparing representative precursors possessing the same metal centre but different ligands or same ligand structure but different metal centres. Representative cases with coinage and transition metals will be illustrated. Alternative approaches to grow metal films and proof-of-concept applications will be demonstrated.
(Invited) Sequential 3D Integration of Ge Transistors on Si CMOS
Authors: Ostling Mikael , Hellstrom Per-Erik 
Published: February 2024

In order to keep the scaling progress going is to go 3D. This paper outlines some technology challenges and solutions to integrate Ge p-type MOSFETs sequentially on Si CMOS. Such a solution addresses the grand challenge to enable increased device density. However, the device itself does not have to scale but at the same time innovative solutions are suggested for low supply voltage operation enabling energy efficient integrated circuits (ICs) that will not be dominated by energy consumption in interconnects.
By stacking the transistors on top of each other, and connect them with inter-tier via, the density of transistors per unit area increases. This approach demands that transistors are fabricated at a lower temperature compared to today’s Si CMOS technology. Therefore, we have focused on Ge based transistors, which has an inherently lower process temperature compared to Si transistors.
In this paper several technological and design breakthroughs towards realizing Ge based sequential 3D circuits will be shown. We will present:

A process to realize thin single crystalline Ge layers on planarized wafers with metal layers in lower tiers.

A gate dielectric stack (Ge/Si/TmSiO/Tm2O3/HfO2/TiN) on Ge that enables adequately low defect densities at the dielectric/Ge interface allowing predictable and reliable Ge transistors

Fully depleted Ge pFET devices fabricated at a low temperature compatible with sequential 3D. The devices exhibits 60% higher mobility compared to reference Si devices.

3D digital circuits with pFETs on top of nFETs can enable area reduction by 30-50% depending on cell type.

3D standard cells with lower parasitic capacitance (~30%) compared to 2D cells, enabling lower dynamic power consumption and more energy efficient integrated circuits.
(Invited) Vertically Stacked Graphene Junction Diodes
Authors: Nagase Masao 
Published: February 2024

Graphene is expected to be nanomaterial of the post-silicon era because of its numerous advantageous properties. The single crystal graphene thermally grown on SiC substrate is considered the most promising platform for future electric devices. Large area epitaxial graphene on SiC substrate has been successfully fabricated using high-temperature rapid thermal annealing [1]. In this study, we present vertically stacked graphene junction diodes fabricated using direct bonding technique [2–4].
Figure 1(a) shows the schematic of a stacked graphene junction diode. Two graphene layers on SiC are directly bonded to each other. Gold–coated contact pins are attached to the graphene surface to establish ohmic contact. The graphene samples and contact probes are fixed by acrylic molds. Strong nonlinear current–voltage (I-V) characteristics are observed for this simple device configuration, as shown in Fig. 1(b). In the low bias voltage (Vb) region, the resistance of the graphene diode is approximately 20 GΩ. The current abruptly increases when the bias voltage is increased to approximately 30 V. The two-terminal resistance at a high bias voltage (100 V) is approximately 21 kΩ. The vertically stacked graphene junction exhibits bidirectional thyristor-type characteristics with a high on-off ratio of approximately 106. The Fowler–Nordheim (F-N) tunneling phenomenon is observed in the sub-threshold region. The gap distance estimated from the F-N plot is approximately 6 nm, which can be attributed to the large off resistance. The Coulomb force generated by applying the bias voltage causes the two graphene layers to attract each other, resulting in an electrically conductive state. The junction voltage (Vj) of the device was measured using a four-terminal configuration. As shown in Fig. 1(c), negative resistance is observed in the low-resistance region. The effective internal resistance of the junction diode is reduced to approximately 450 Ω. The off resistance of the diodes is considerably modified by the initial distance between the graphene layers. However, the I-Vj characteristics in the negative resistance region are identical for each device. This result suggests that the cause of the negative resistance phenomena is closely related to the band structure of graphene.
A vertically stacked graphene junction diode with a high on-off ratio was demonstrated. The main component of the diode comprised a pair of single-crystal graphene layers fabricated through direct bonding. The negative resistance of the graphene diode presents new possibilities for the application of functional devices, such as terahertz emitters.
[1] T. Aritsuki, et al., Jpn. J. Appl. Phys. 55 (2016) 06GF03.
[2] J. Du, eta al., Jpn. J. Appl. Phys. 58 (2019) SDDE01.
[3] N. Murakami, et al., Jpn. J. Appl. Phys. 60 (2021) SCCD01.
[4] M. Ohi, et al., Jpn. J. Appl. Phys. 62 (2023) to be published.

Figure 1
(Invited) Optical Biosensors in Photonic Integrated Circuits for Smart System Integration
Authors: Steglich Patrick , Paul Martin , Mai Christian , Lecci Giulia , Weller Michael G. , Mai Andreas 
Published: February 2024

Photonic integrated circuits (PIC) are like electronic integrated circuits drivers of communication systems. Moreover, state-of-the-art technologies enable the fabrication of electronic-photonic integrated circuits (ePIC), which allows for example the cointegration of ultra-fast BiCMOS devices with high speed photo detectors. Besides that, this technology provides an attractive platform for biosensors. They open the door for label-free detection of various analytes with high specificity and in real-time. This gives perspective to highly scalable and cost effective technologies for smart system integration of biosensors and electronic readouts to realize a true lab-on-a-chip application.
We present the integration of optical biosensors in a Si-based PIC-technology. This comprises a front-end of line with optical waveguides, an integrated Ge-photodiode and a complete back-end of line consisting of three thin and two thick aluminum metal layers. The optical biosensor is integrated by opening the optical waveguide from the backside of the chip. In particular, we released a Si-based slot waveguide, which provides an enhanced evanescent field to interact with the analyte and hence to increase the sensitivity. The slot waveguide is incorporated in a ring resonator and we analyzed the wafer-level performance using the full width at half maximum, which allows us to assess the optical losses. Thermal sensing in a wide temperature range is investigated. In addition, a simple and cost-effective microfluidic is realized and we show initial results of the surface functionalization. Our work demonstrates the compatibility of a photonic biosensor with a photonic integrated circuit technology without any restriction to the standard FEOL and BEOL processing on the wafer front-side, while it keeps the inherent high sensitivity of evanescent-field sensing and opens a route towards smart system integration.

Figure 1
Silicon-Germanium on Insulator CMP Slurry Designed with Oxidant and Accelerator Heading an Amine Functional Group for Remarkably Enhancing Polishing Rate
Authors: Han Manhyup Han , Kim Eun-Seong , Lee Kyung-Sik , Park Jea-gun 
Published: February 2024

High quality single crystal silicon-germanium-on-insulator (SGOI) has a potential to enable the next generation
of photonic and electronic devices. However, to utilize an SGOI structure, a high SiGe-film polishing rate is
necessary (i.e., > 200 nm/min) for polishing the facet crystalline SiGe during the fabrication of SiGe on insulator
through epitaxial growth processes.
In previous studies, amine-based chemicals as SiGe-film polishing rate accelerators have been reported, but
there were limitations in increasing the SiGe-film polishig rate by considering only the chemical reaction of SiGe-
film surface. In this study, for the first time, both oxidant(i.e., H2O2) and accelerator with amine functional groups
(i.e., triethanolamine) were designed, resulting in a surprising increase in the SiGe-film polishing rate of 270
nm/min, as shown Fig. 1a.
The SiGe chemical mechanical planarization (CMP) mechanism was clearly demonstrated by precisely
investigating both chemical properties(i.e., GeO2 spectra intensity via X-ray photoelectron spectroscopy) and
mechanical properties(i.e., electrostatic repulsive force between colloidal silica abrasives and the SiGe-film via
electrophoretic light scattering). The remarkable enhancement of the SiGe-film polishing rate for oxidant and
triethanolamine was the result of (i) minimizing the loss of degree of SiGe surface oxidation, as shown Fig. 2, (ii)
enhancing degree of adsorption of the CMP slurry on the polished SiGe-film surface during CMP, and (iii)
decreasing the electrostatic repulsive force between colloidal silica abrasives and the SiGe-film surface, as shown
Fig 1b. Finally, successful removal of the facets in SiGe on insulator wafers was achieved, securing excellent
surface roughness characteristics. SiGe-film polishing mechanism and the SiGe slurry characteristics will be
presented in detail.

Figure 1
Recent Theoretical Advancement of Boron-Rich Compounds for Applications in High-Density Energy Conversion Devices
Authors: Liu Bin 
Published: February 2024

Boron-rich compounds (IBCs) such as boron suboxide (B6O) and boron subphosphide (B12P2) are derived from the α-rhombohedral boron lattice with extreme hardness and unusual electrical properties. These compounds display an extraordinary self-healing ability to repair the lattice defects generated from exposure to high-energy irradiation. This unique ability will enable these boron-rich compounds to be deployed in nuclear battery devices for space or deep-sea exploration applications when coupled with their high hole mobility.
Synthesis and control of the stoichiometry of IBCs are the key technical challenge. For instance, the electrical properties of B6O are susceptible to specific B:O ratios. Thus far, the highest quality B6O crystals were obtained from high-pressure, high-temperature (HP-HT) experiments using mixed boron and boron oxide powders. Nevertheless, a mature synthesis protocol yielding consistent, high-quality B6O crystals has not been established.
In this talk, density functional theory (DFT) was used to understand how the structural, electronic, and thermodynamic stabilities of B6O (and other IBCs) are influenced by the interstitial elements and point defects at the icosahedral sites. Using the hybrid HSE functional, we confirmed that the perfect B6O bulk is a p-type semiconductor with a direct band gap of 2.8 eV. Furthermore, by screening the α-boron compounds systematically, we found that a simple octet rule may offer a consistent explanation for the variations in the computed electronic structures. Then, the thermodynamic calculations based on the DFT method predict that formations of interstitial defects become favorable only at higher temperatures.
To understand the self-healing property, the nudged elastic band (NEB) method was employed to identify the minimum energy pathways for the diffusions of dislocated B and O atoms. The diffusion of icosahedral B atoms has an energy barrier of 0.16 eV, confirming that the boron vacancies can be repaired with little kinetic limitation. Nevertheless, a substantially perturbed lattice requires more complex structural reorganization and thus incurs higher barriers (> 1 eV).
Lastly, reactive molecular dynamics simulations with a frozen core were performed to gain insights into the initial crystal nucleation process using a newly developed ReaxFF force field. For the first time, we can gain a molecular perspective on the formations of the boron icosahedra (B12) motif and the energetic profile. Such knowledge will aid the experimental design of IBC synthesis.