Magnetism and Antiferroelectricity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>MgB</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:math>

Popov, Igor; Baâdji, N.; Sanvito, Stefano

doi:10.1103/physrevlett.108.107205

Cited by 39 publications

(34 citation statements)

References 31 publications

(36 reference statements)

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“…Considering charge-transfer at the metal MoS2 interface alone for these high work function metals, the different contact nature of Pd from Ni and Au is somewhat unexpected. Indeed, recent ab inito calculations suggest that the modification of the electronic states at the interface by the metal is the key to understanding the contact to MoS2, going beyond the simple charge-transfer considerations of a metal-semiconductor junction [2]. To investigate the Ni contact further, Rc was measured at low temperature via TLM, as shown in Figure 4, for a �6nm thick flake, as estimated by optical contrast.…”

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confidence: 99%

Metal contacts to MoS<inf>2</inf>: A two-dimensional semiconductor

Neal

Liu

et al. 2012

70th Device Research Conference

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With increasing demands for electrostatic control as scaling continues in today's transistors, low dimensional structures continue to gain attention as a pathway for future device scaling because they offer excellent electrostatic control while remaining compatible with straightforward lithography techniques.In particular, MoS2 has attracted interest for transistor applications because its large band gap allows for field effect devices with low off-current, unlike graphene [1]. One key bottleneck, however, is the realization of ohmic contacts on MoS2 to improve FET device on-state performance. With this in mind, we evaluate Ni and Pd contacts on MoS2 as potential alternatives to the already realized Au-MoS2 and Ti MoS2 contacts [1]. Back-gated transfer length method (TLM) structures with Au, Ni, and Pd contact metals were fabricated on exfoliated MoS2 flakes, with 300nm Si02 on degenerately doped Si as the substrate. The data indicate that Ni, like Au, makes an ohmic contact to the n-doped MoS2 while the Pd metal contact shows Schottky behavior.Figure 1 shows the alignment of the metal work-functions to the MoS2 bands for the high work function metals on which we focus in this work. Figure 2 shows representative Ia Vds characteristics at Vbg=SOV for the three contact metals on MoS2• The MoS2 flake thicknesses are Snm for Ni and 6nm for Au, measured by AFM, and � 13nm for Pd, estimated by optical contrast. One finds that the Ni and Au contacts are ohmic while the Pd contact shows Schottky behavior. Figure 3 shows the contact resistance (Re) as a function of back-gate voltage (Vbg), extracted using the TLM. Re for Ni and Au are found to be comparable, with a minimum Rc of about 4.SQ.mm at Vbg=SOV. The gate-dependent Rc reflects the gate modulation of the potential barrier at the metal-MoS2 interface. Considering charge-transfer at the metal MoS2 interface alone for these high work function metals, the different contact nature of Pd from Ni andAu is somewhat unexpected. Indeed, recent ab inito calculations suggest that the modification of the electronic states at the interface by the metal is the key to understanding the contact to MoS2, going beyond the simple charge-transfer considerations of a metal-semiconductor junction [2]. To investigate the Ni contact further, Rc was measured at low temperature via TLM, as shown in Figure 4, for a �6nm thick flake, as estimated by optical contrast. The Rc varies weakly with temperature, increasing by less than a factor of two from 238K to 78K for any Vbg• Enabled by the low temperature Ni ohmic contact, the sheet resistance and mobility of MoS2 could be extracted as shown in Figure S. The mobility, extracted from fits to the sheet resistance as a function of Vbg, is determined to be 48 cm 2 /Vs at 289K, increasing to 237 cm 2 /Vs at 78K due to decreased phonon scattering. The mobility of MoS2 could be significantly improved to several hundred cm 2 /Vs if its surface is passivated by atomic-layer-deposited dielectrics. [1, 3] The temperature dependence of the mobility is powe...

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confidence: 99%

Metal contacts to MoS<inf>2</inf>: A two-dimensional semiconductor

Neal

Liu

et al. 2012

70th Device Research Conference

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“…Furthermore, to make devices out of 2D TMDs, contact with metals is unavoidable. [12][13][14] The nature and quality of the 2D TMD-metal contact is crucial to the performance of various devices, and low contact resistance is vital to reveal the prominent intrinsic transport properties of TMDs. The formation of a low resistance metal contact is a great challenge due to the following facts: (1) it is easy to form a tunnel barrier at a TMD-metal contact caused by the van der Waals (vdW) gap, which impedes electron injection; and (2) a finite Schottky barrier (SB) usually appears at the interface between the metal and TMD that lowers the carrier injection efficiency.…”

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confidence: 99%

Interfacial Properties for a Monolayer CrS₂ Contact with Metal: A Theoretical Perspective

Habib

Wang

Obaidulla

et al. 2019

Physica Status Solidi (b)

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Limited calculations show that monolayer (ML) chromium dichalcogenide (CrS2) has a direct bandgap and valley polarization but with a smaller bandgap than ML MoS2 and with distinct piezoelectric and ferromagnetic properties. It is highly desirable to determine an appropriate metal contact for novel two‐dimensional (2D) CrS2‐based devices. By using density functional theory (DFT), the interface between ML CrS2 and commonly used metals, including s‐electron and d‐electron metals, is studied systematically by evaluating the binding energy, Schottky barrier, orbital overlap, and tunneling barrier at the interfaces. The d‐electron metals show higher binding energy with the ML CrS2 than the s‐electron metals, which is due to the different occupancy and position of the d‐band of the metals. A strong Fermi level pinning is found in the metal–CrS2 contacts. Both n‐type and quasi p‐type phenomena for CrS2 with respect to pristine CrS2 can be produced at the CrS2 contacts with the metals. The higher overlap states between the CrS2 and Ti result in a higher minimum electron density at the Schottky interface, suggesting that Ti is the best contact among the investigated metals for use in CrS2‐based devices for efficient electron injection. The DFT results provide a guideline that is invaluable for experimentally designing novel 2D CrS2 semiconductor devices.

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“…1 Introduction Since the discovery of graphene, twodimensional (2D) nanomaterials have received significant attention because of their attractive applications in nanoscience and condensed-matter physics [1,2]. Similar to graphene, layered transition-metal dichalcogenides (TMDCs) with strong inplane covalent bonding and weak out-of-plane van der Waals' bonding have also been extensively studied in recent years [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In particular, several 2D semiconducting TMDCs, such as WS 2 , MoS 2 , and WSe 2 , possess sizable bandgaps around 1-2 eV, promising candidates of the nextgeneration field-effect transistors and optoelectronic devices [17].…”

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confidence: 99%

“…By using a controlled thermal reduction-sulfurization method, large-area (~1 cm 2 ) WS 2 sheets with thicknesses ranging from monolayers to a few layers have been successfully synthesized [9]. Many inspiring physicochemical properties have been further examined, including transport [10], photocurrent [11], photoluminescence [3,4,12], stiffness [13], magnetism [14], and valley polarization [15,16].…”

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Metal-atom-induced charge redistributions and their effects on the electrical contacts to WS₂ monolayers

Zhou

Zhu

Yang

et al. 2015

Phys. Status Solidi B

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The structural and electronic properties of high work function metal atoms (Au and Pd) and low work function metal atoms (Ti and In) adsorbed WS2 monolayers are systematically studied using first‐principles calculations. Due to the weak interaction between Au and S atoms, high Schottky barriers may be formed at the interface. Using the metal Pd contact, p‐type ohmic contact may be fabricated, but the localized and sparse partial charge densities decrease the electronic transparency and increase the contact resistance. For the low work function metal In, the delocalized n‐type conduction interface states form in the bandgap; however, the wide and high electrostatic potential barrier suppresses the electron‐transition probability. Strikingly different from Au, Pd, and In, the strongest interaction between Ti and S atoms induces the delocalized n‐type conduction interface states with the highest electronic states near the Fermi level. The delocalized and high partial charge densities, as well as the narrowest and lowest electrostatic potential barrier, would enhance the electronic transparency and form the n‐type ohmic contact. Furthermore, the results of the multilayer metal contacts are consistent with those of the atom‐adsorbed systems. These investigations offer valuable resources for the design and fabrication of two‐dimensional nanodevices.

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Magnetism and Antiferroelectricity inMgB6

Cited by 39 publications

References 31 publications

Metal contacts to MoS<inf>2</inf>: A two-dimensional semiconductor

Metal contacts to MoS<inf>2</inf>: A two-dimensional semiconductor

Interfacial Properties for a Monolayer CrS₂ Contact with Metal: A Theoretical Perspective

Metal-atom-induced charge redistributions and their effects on the electrical contacts to WS₂ monolayers

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Magnetism and Antiferroelectricity inMgB6

Cited by 39 publications

References 31 publications

Metal contacts to MoS<inf>2</inf>: A two-dimensional semiconductor

Metal contacts to MoS<inf>2</inf>: A two-dimensional semiconductor

Interfacial Properties for a Monolayer CrS2 Contact with Metal: A Theoretical Perspective

Metal-atom-induced charge redistributions and their effects on the electrical contacts to WS2 monolayers

Contact Info

Product

Resources

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Interfacial Properties for a Monolayer CrS₂ Contact with Metal: A Theoretical Perspective

Metal-atom-induced charge redistributions and their effects on the electrical contacts to WS₂ monolayers