Monolayer Vanadium‐Doped Tungsten Disulfide: A Room‐Temperature Dilute Magnetic Semiconductor

Abstract

Dilute magnetic semiconductors (DMS), achieved through substitutional doping of spin-polarized transition metals into semiconducting systems, enable experimental modulation of spin dynamics in ways that hold great promise for novel magneto-electric or magneto-optical devices, especially for two-dimensional (2D) systems such as transition metal dichalcogenides that accentuate interactions and activate valley degrees of freedom. Practical applications of 2D magnetism will likely require room-temperature operation, air stability, and (for magnetic semiconductors) the ability to achieve optimal doping levels without dopant aggregation. Here, room-temperature ferromagnetic order obtained in semiconducting vanadium-doped tungsten disulfide monolayers produced by a reliable single-step film sulfidation method across an exceptionally wide range of vanadium concentrations, up to 12 at% with minimal dopant aggregation, is described. These monolayers develop p-type transport as a function of vanadium incorporation and rapidly reach ambipolarity. Ferromagnetism peaks at an intermediate vanadium concentration of˜2 at% and decreases for higher concentrations, which is consistent with quenching due to orbital hybridization at closer vanadium-vanadium spacings, as supported by transmission electron microscopy, magnetometry, and first-principles calculations. Room-temperature 2D-DMS provide a new component to expand the functional scope of van der Waals heterostructures and bring semiconducting magnetic 2D heterostructures into the realm of practical application.

One-step synthesis of single-site vanadium substitution in 1T-WS2 monolayers for enhanced hydrogen evolution catalysis

“…8 and 9 . Simultaneously, both the V atoms and S atoms are prominently discernible, in consistent with the STEM images of V-doped 2H-TMDs 35 – 37 . As a result, the substitutional V atoms are at an average concentration of 4.0 at% (~2.0 wt%) in the 1T-WS 2 layer.…”

“…6 and 7 ). It is anticipated that the V and S atoms could become visible if the 1T phase is transformed into the 2H phase, which has been shown in a pre-published literature 35 . To further confirm the V-atom concentration in the 1T-WS 2 layer, we anneal the 1T-WS 2 sample at 200 °C (in the air for 30 min) for STEM imaging and find that the 1T phase is completely transformed into the 2H phase, as shown in Supplementary Figs.…”

Substitutional doping in 2D transition metal dichalcogenides

“…4(a)). Such a spatial variation was also observed in V-doped WS2 [85]. Nb dopants introduce an acceptor state in MoS2 above a doping density of 8% [29,32,79].…”

“…4(d)). With the same W liquid precursor and VO[SO4], Zhang et al [85] reported the growth of V-doped WS2 monolayers with V densities ranging from 0.4% to 12% with minimal dopant aggregation. V introduces an acceptor state situated approximately 0.14 eV above the VBM as measured by STS over individual dopants in WSe2 [87].…”

Enhanced Electrical Performance of Monolayer MoS2 with Rare Earth Element Sm Doping

“…However, in these previous doping schemes, ion injection and surface charge transfer in monolayer 2D-TMDC doping were often not stable enough, thus limiting their application [ 6 , 7 ]. Substitution the doping of 2D-TMDCs has been widely explored for materials applications in electronic and optoelectronic [ 7 ], as well as room-temperature ferromagnetism, applications [ 8 , 9 , 10 ]. Transition elements have been used as cationic substitutes for doped 2D-TMDCs, e.g., the Nb ion-doped 2D-TMDCs achieving p-type [ 7 ] transport characteristics and the Re ion-doped 2D-TMDCs achieving nearly degenerate n-type doping [ 11 ].…”