Visualizing the metal-
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Mo</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
 contacts in two-dimensional field-effect transistors with atomic resolution

Wu, Ryan; Udyavara, Sagar; Wang, Yan; Chhowalla, Manish; Birol, Turan; Koester, Steven J.; Neurock, Matthew; Mkhoyan, K. Andre

doi:10.1103/physrevmaterials.3.111001

Cited by 35 publications

(42 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It also confirms that our ferromagnet layer shows less affinity to sulfur because metals having a large affinity to sulfur can degrade the 2D characteristics of TMDs. 27 Figure 1 b shows the room-temperature Raman spectra recorded on a single-layer TaS 2 film using two different lasers. Strong fundamental peaks are observed at 305 and 231 cm –1 , corresponding to the 1T-TaS 2 phase.…”

Section: Resultsmentioning

confidence: 99%

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS₂ Monolayer

et al. 2020

View full text Add to dashboard Cite

A damping-like spin-orbit torque (SOT) is a prerequisite for ultralow-power spin logic devices. Here, we report on the damping-like SOT in just one monolayer of the conducting transition-metal dichalcogenide (TMD) TaS 2 interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion efficiency is found to be 0.25 ± 0.03 in TaS 2 (0.88)/Py(7), and the spin Hall conductivity is found to be superior to values reported for other TMDs. We also observed sizable field-like torque in this heterostructure. The origin of this large damping-like SOT can be found in the interfacial properties of the TaS 2 /Py heterostructure, and the experimental findings are complemented by the results from density functional theory calculations. It is envisioned that the interplay between interfacial spin–orbit coupling and crystal symmetry yielding large damping-like SOT. The dominance of damping-like torque demonstrated in our study provides a promising path for designing the next-generation conducting TMD-based low-powered quantum memory devices.

show abstract

Section: Resultsmentioning

confidence: 99%

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS₂ Monolayer

et al. 2020

View full text Add to dashboard Cite

show abstract

“… 34 , 35 For example, McDonnell et al 35 have demonstrated that when a Ti contact is deposited on MoS 2 at high vacuum (HV) (pressure >10 –6 mbar), Ti is likely to react with oxygen and form TiO x at the interface, owing to the background oxygen present at such pressures. On the other hand, for ultrahigh vacuum (UHV) environments (pressure <10 –9 mbar), Ti shows a stronger reaction with the underlying MoS 2 , resulting in the formation of Ti–S bonds at the interface 35 and disruption of the semiconducting layer beneath as well as its electronic band structure, 31 , 36 leaving behind gap states mainly of Mo character. 26 , 31 , 36 Several efforts have been made in recent years to control the gap state formation.…”

Section: Introductionmentioning

confidence: 99%

On the Contact Optimization of ALD-Based MoS₂ FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance

Mahlouji

Zhang

Verheijen

et al. 2021

ACS Appl. Electron. Mater.

View full text Add to dashboard Cite

Despite the extensive ongoing research on MoS 2 field effect transistors (FETs), the key role of device processing conditions in the chemistry involved at the metal-to-MoS 2 interface and their influence on the electrical performance are often overlooked. In addition, the majority of reports on MoS 2 contacts are based on exfoliated MoS 2 , whereas synthetic films are even more susceptible to the changes made in device processing conditions. In this paper, working FETs with atomic layer deposition (ALD)-based MoS 2 films and Ti/Au contacts are demonstrated, using current–voltage ( I – V ) characterization. In pursuit of optimizing the contacts, high-vacuum thermal annealing as well as O 2 /Ar plasma cleaning treatments are introduced, and their influence on the electrical performance is studied. The electrical findings are linked to the interface chemistry through X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) analyses. XPS evaluation reveals that the concentration of organic residues on the MoS 2 surface, as a result of resist usage during the device processing, is significant. Removal of these contaminations with O 2 /Ar plasma changes the MoS 2 chemical state and enhances the MoS 2 electrical properties. Based on the STEM analysis, the observed progress in the device electrical characteristics could also be associated with the formation of a continuous TiS x layer at the Ti-to-MoS 2 interface. Scaling down the Ti interlayer thickness and replacing it with Cr is found to be beneficial as well, leading to further device performance advancements. Our findings are of value for attaining optimal contacts to synthetic MoS 2 films.

show abstract

“…Understanding the origin of these distinctive functionalities in materials therefore critically relies on our ability to accurately measure both electron's degrees of freedom and lattice for revealing their complex interactions. Over the years, the remarkable progress in the microscopy, spectroscopy and diffraction has enabled to probe the lattice, charge and spin with high precision and sensitivity, which has made significant contributions to reveal fundamental physical mechanisms for the relevant functional properties that have made up the cornerstone of current electric devices (such as field-effect transistors, magnetic random-access memory and piezoelectric transducers) [5][6][7][8][9] . By contrast, much less advancement has been made on the detection and characterization of electron orbital on a specific atom in the materials.…”

mentioning

confidence: 99%

Direct visualization of orbital electron occupancy

Shang

Xiao

Meng

et al. 2021

Preprint

View full text Add to dashboard Cite

Orbital is one of the primary physical parameters that determine materials’ properties. Currently, experimentally revealing the electron occupancies of orbitals under the control of external field remains a big challenge due to the stringent requirements for samples such as the atomically sharp surface or defect-free large-size single crystals. Here, we developed a method with the combination of quantitative convergent-beam electron diffraction and synchrotron powder X-ray diffraction, and demonstrated the visualization of the real-space orbital occupancy by choosing LiCoO2 as a prototype. Through multipole modelling of the accurately measured structure factors, we found the opposite changes of Co t2g and eg orbital occupancies under different electrochemical states which can be well-correlated with the CoO6 octahedra distortion. This robust method provides a feasible route to quantify the real-space orbital occupancy on small-sized particles, and opens up a new avenue for exploring the orbital origin of physical properties for functional materials.

show abstract

Visualizing the metal- MoS2 contacts in two-dimensional field-effect transistors with atomic resolution

Cited by 35 publications

References 57 publications

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS₂ Monolayer

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS₂ Monolayer

On the Contact Optimization of ALD-Based MoS₂ FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance

Direct visualization of orbital electron occupancy

Contact Info

Product

Resources

About

Visualizing the metal- MoS2 contacts in two-dimensional field-effect transistors with atomic resolution

Cited by 35 publications

References 57 publications

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS2 Monolayer

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS2 Monolayer

On the Contact Optimization of ALD-Based MoS2 FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance

Direct visualization of orbital electron occupancy

Contact Info

Product

Resources

About

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS₂ Monolayer

Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS₂ Monolayer

On the Contact Optimization of ALD-Based MoS₂ FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance