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DOE OSTI2020

Materials Data on Te2Mo(WS2)2 by Materials Project

MoTe2(WS2)2 is Molybdenite-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one MoTe2 sheet oriented in the (0, 0, 1) direction and two WS2 sheets oriented in the (0, 0, 1) direction. In the MoTe2 sheet, Mo6+ is bonded to six equivalent Te2- atoms to form distorted edge-sharing MoTe6 pentagonal pyramids. All Mo–Te bond lengths are 2.70 Å. Te2- is bonded to three equivalent Mo6+ atoms to form a mixture of distorted face and corner-sharing TeMo3 cuboctahedra. In each WS2 sheet, W3+ is bonded to six S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.45 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent W3+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)2 by Materials Project

MoTe2(WS2)2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoTe2 sheet oriented in the (0, 0, 1) direction and two WS2 sheets oriented in the (0, 0, 1) direction. In the MoTe2 sheet, Mo6+ is bonded to six Te2- atoms to form distorted edge-sharing MoTe6 pentagonal pyramids. All Mo–Te bond lengths are 2.70 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In the second Te2- site, Te2- is bonded to three equivalent Mo6+ atoms to form distorted corner-sharing TeMo3 cuboctahedra. In each WS2 sheet, W3+ is bonded to six S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.45 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent W3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)3 by Materials Project

WTe2(WS2)2MoS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoS2 sheet oriented in the (0, 0, 1) direction; two WS2 sheets oriented in the (0, 0, 1) direction; and one WTe2 sheet oriented in the (0, 0, 1) direction. In the MoS2 sheet, Mo6+ is bonded to six equivalent S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. All Mo–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In each WS2 sheet, W+3.33+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W+3.33+ atoms. In the WTe2 sheet, W+3.33+ is bonded in a 6-coordinate geometry to six Te2- atoms. All W–Te bond lengths are 2.71 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent W+3.33+ atoms. In the second Te2- site, Te2- is bonded in a 12-coordinate geometry to three equivalent W+3.33+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)3 by Materials Project

MoTe2(WS2)3 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoTe2 sheet oriented in the (0, 0, 1) direction and three WS2 sheets oriented in the (0, 0, 1) direction. In the MoTe2 sheet, Mo6+ is bonded in a 6-coordinate geometry to six Te2- atoms. All Mo–Te bond lengths are 2.70 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In the second Te2- site, Te2- is bonded to three equivalent Mo6+ atoms to form distorted corner-sharing TeMo3 cuboctahedra. In each WS2 sheet, W+3.33+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W+3.33+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)3 by Materials Project

36 MATERIALS SCIENCE↗

DOE OSTI2021

Direct observation of negative differential resistance in WS2 homojunction

Vertical tunneling junctions showing negative differential resistance (NDR) are realized in WS2 homojunction devices. Mono-/multilayered single crystalline WS2 is grown using chemical vapor deposition. NDR is observed through resonant tunneling in Au/bi-layer WS2/Au and Pt/few-layered WS2/Au tunneling junctions by back-gating at room temperature. While two-dimensional materials have been a central focus of materials research during the past decade, exploiting novel properties in diverse layers of these materials is emerging with new designs for electronic devices. Our results pave the way for novel resonant tunneling devices presenting a route to fabricate homojunction WS2 with simple fabrication techniques.

Hsu, Bo (ORCID:0000000201714211)↗

DOE OSTI2020

Materials Data on WS2 by Materials Project

WS2 is Molybdenite structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two WS2 sheets oriented in the (0, 0, 1) direction. W4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W4+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on WS2 by Materials Project

WS2 is Molybdenite-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three WS2 sheets oriented in the (0, 0, 1) direction. W4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W4+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on WS2 by Materials Project

WS2 is Molybdenite-like structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one WS2 sheet oriented in the (0, 0, 1) direction. W4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W4+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on WS2 by Materials Project

WS2 is Molybdenite-like structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of two WS2 sheets oriented in the (0, 0, 1) direction. W4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W4+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)2 by Materials Project

WTe2WS2MoS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoS2 sheet oriented in the (0, 0, 1) direction; one WS2 sheet oriented in the (0, 0, 1) direction; and one WTe2 sheet oriented in the (0, 0, 1) direction. In the MoS2 sheet, Mo6+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. All Mo–S bond lengths are 2.44 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Mo6+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In the WS2 sheet, W3+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.45 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms. In the WTe2 sheet, W3+ is bonded to six Te2- atoms to form distorted edge-sharing WTe6 pentagonal pyramids. All W–Te bond lengths are 2.71 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 12-coordinate geometry to three equivalent W3+ atoms. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on WS2 by Materials Project

WS2 is Molybdenite-like structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of three WS2 sheets oriented in the (0, 0, 1) direction. W4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W4+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)2 by Materials Project

WTe2WS2MoS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoS2 sheet oriented in the (0, 0, 1) direction; one WS2 sheet oriented in the (0, 0, 1) direction; and one WTe2 sheet oriented in the (0, 0, 1) direction. In the MoS2 sheet, Mo6+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are three shorter (2.44 Å) and three longer (2.45 Å) Mo–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Mo6+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In the WS2 sheet, W3+ is bonded to six S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.45 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent W3+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms. In the WTe2 sheet, W3+ is bonded to six equivalent Te2- atoms to form distorted edge-sharing WTe6 pentagonal pyramids. All W–Te bond lengths are 2.71 Å. Te2- is bonded in a 12-coordinate geometry to three equivalent W3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Te2Mo(WS2)2 by Materials Project

WTe2WS2MoS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoS2 sheet oriented in the (0, 0, 1) direction; one WS2 sheet oriented in the (0, 0, 1) direction; and one WTe2 sheet oriented in the (0, 0, 1) direction. In the MoS2 sheet, Mo6+ is bonded to six equivalent S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. All Mo–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In the WS2 sheet, W3+ is bonded to six S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.45 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent W3+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms. In the WTe2 sheet, W3+ is bonded to six Te2- atoms to form distorted edge-sharing WTe6 pentagonal pyramids. All W–Te bond lengths are 2.71 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 12-coordinate geometry to three equivalent W3+ atoms. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent W3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on WS2 by Materials Project

WS2 is Molybdenite-like structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of four WS2 sheets oriented in the (0, 0, 1) direction. W4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W4+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Graphene-driven correlated electronic states in one dimensional defects within WS2

Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of one-dimensional defects hosting a Fermi liquid or a TLL have suggested a dependence on the underlying substrate, however, unveiling the physical details of electronic contributions from the substrate require cross-correlative investigation. Here, we study TLL formation within defectively engineered WS2 atop graphene, where band structure and the atomic environment is visualized with nano angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and spectroscopy, and non-contact atomic force microscopy. Correlations between the local density of states and electronic band dispersion elucidated the electron transfer from graphene into a TLL hosted by one-dimensional metal (1DM) defects. It appears that the vertical heterostructure with graphene and the induced charge transfer from graphene into the 1DM is critical for the formation of a TLL.

Rossi, Antonio↗

DOE OSTI2020

Dispersion of the Nonlinear Susceptibility of MoS2 and WS2 from Second-Harmonic Scattering Spectroscopy

Dispersion of the absolute second-order susceptibility of both MoS2 and WS2 is assessed on a wide spectral excitation range (710–1300 nm) by using second-harmonic scattering spectroscopy (SHS). SHS is an accurate ensemble measurement here applied on well-dispersed suspensions of monodisperse liquid-exfoliated nanosheets showing a high monolayer content. The as-derived, high susceptibility values shed light on the discrepancies between available literature values while evidencing resonances associated with the main excitonic transitions.

CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SU↗

DOE OSTI2020

Spatially Resolved Persistent Photoconductivity in MoS2–WS2 Lateral Heterostructures

The optical and electronic properties of 2D semiconductors are intrinsically linked via the strong interactions between optically excited bound species and free carriers. Here we use near-field scanning microwave microscopy (SMM) to image spatial variations in photoconductivity in MoS 2 –WS 2 lateral multijunction heterostructures using photon energy-resolved narrowband illumination. We find that the onset of photoconductivity in individual domains corresponds to the optical absorption onset, confirming that the tightly bound excitons in transition metal dichalcogenides can nonetheless dissociate into free carriers. These photogenerated carriers are most likely n-type and are seen to persist for up to days. Informed by finite element modeling we reveal that they can increase the carrier density by up to 200 times. This persistent photoconductivity appears to be dominated by contributions from the multilayer MoS 2 domains, and we attribute the flake-wide response in part to charge transfer across the heterointerface. Spatial correlation of our SMM imaging with photoluminescence (PL) mapping confirms the strong link between PL peak emission photon energy, PL intensity, and the local accumulated charge. This work reveals the spatially and temporally complex optoelectronic response of these systems and cautions that properties measured during or after illumination may not reflect the true dark state of these materials but rather a metastable charged state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗