Phase patterning for ohmic homojunction contact in MoTe ₂

Abstract

Artificial van der Waals heterostructures with two-dimensional (2D) atomic crystals are promising as an active channel or as a buffer contact layer for next-generation devices. However, genuine 2D heterostructure devices remain limited because of impurity-involved transfer process and metastable and inhomogeneous heterostructure formation. We used laser-induced phase patterning, a polymorph engineering, to fabricate an ohmic heterophase homojunction between semiconducting hexagonal (2H) and metallic monoclinic (1T') molybdenum ditelluride (MoTe2) that is stable up to 300°C and increases the carrier mobility of the MoTe2 transistor by a factor of about 50, while retaining a high on/off current ratio of 10(6). In situ scanning transmission electron microscopy results combined with theoretical calculations reveal that the Te vacancy triggers the local phase transition in MoTe2, achieving a true 2D device with an ohmic contact.

Room‐Temperature Nanoseconds Spin Relaxation in WTe2 and MoTe2 Thin Films

“…The optical microscopy image (Figure S7a, Supporting Information), Raman spectra (Figure S7c, Supporting Information), Raman mapping (Figure S7d, Supporting Information), and XPS (Figure S8, Supporting Information) verify the pure and uniform Td phase of MoTe 2 thin film 12, 16. The quantitative analysis derived from the XPS spectra shows that the atomic ratio of Te to W(Mo) in few‐layer WTe 2 and MoTe 2 is ≈2, which is consistent with the stoichiometric amount of WTe 2 and MoTe 2 .…”

Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors

“…To date, various innovative strategies to reduce the contact resistance such as use of 3 graphene contacts 3,[18][19][20] and phase-engineering, 21,22 are still deficient as they do not offer true ohmic contact behavior or have insufficient thermal stability. Nearly barrier-free contacts to MoS 2 have been achieved by using graphene as contact electrodes because the Fermi level of graphene can be effectively tuned by a gate voltage to align with the conduction band minimum ( CBM ) of MoS 2 , which minimizes the Schottky barrier height (SBH).…”

Engineering the Structural and Electronic Phases of MoTe2 through W Substitution

“…The T d−phase is predicted to possess unique topological properties [6][7][8][9] which might lead to topologically protected non-dissipative transport channels 9 . Recently, it was argued that it is possible to locally induce phasetransformations in TMDs 3,10,11,14 , through chemical doping 12 , local heating 13 , or electric-field 14,15 to achieve ohmic contacts or to induce useful functionalities such as electronic phase-change memory elements 11 . The combination of semiconducting and topological elements based upon the same compound, might produce a new generation of high performance, low dissipation optoelectronic elements.…”