Direct Formation of Stable 1T′ Molybdenum Telluride (MoTe2) by Laser Annealing Processes as Robust Contacts for High-Performance Molybdenum Disulfide (MoS2) Field Effect Transistors

TL;DR

A new laser method creates stable, high-performance contacts for 2D transistors, enabling better performance and heat resistance.

Contribution

A scalable laser annealing process to form 1T′-MoTe2 contacts for MoS2 FETs with high thermal stability.

Findings

1T′-MoTe2 contacts enable near-zero Schottky barriers and high device performance in MoS2 FETs.

1T′-MoTe2 electrodes maintain high on/off ratios up to 500 °C, outperforming Bi contacts.

Laser-formed 1T′-MoTe2 contacts preserve MoS2 integrity and ensure large-area uniformity.

Abstract

Semimetals, with
their low density of states near the Fermi level,
effectively suppress metal-induced gap states, enabling near-zero
Schottky barrier heights in two-dimensional (2D) field-effect transistors
(FETs). However, the low melting point of semimetals (Bi, Sb) limits
the applications of 2D FETs at high temperatures. Here, we introduce
a robust semimetal contact strategy for high-performance MoS2 FETs, based on continuous-wave laser annealing of elemental metals
(Bi, Mo, Pt, W) and tellurium to form metal tellurides. Specifically,
the phase of molybdenum telluride (1T′/2H) can be prepared
under different laser parameters. In particular, large-area, high-crystallinity
films of stable 1T′-MoTe2 can be synthesized uniformly,
and source/drain electrodes of 1T′-MoTe2 are formed
directly from elemental Mo and Te without damaging the underlying
MoS2. Electrical characterization shows that MoS2 FETs with 1T′-MoTe2 contacts match the performance
of Bicontacted devices and maintain device uniformity over large areas.
Moreover, 1T′-MoTe2 electrodes sustain excellent
on/off ratios of ∼108 after an annealing temperature
at 400 °C and ∼105 after 500 °C,
whereas Bi contacts fail at 400 °C. This laser annealing
approach offers a scalable method to fabricate robust electrodes for
2D transistors, paving the way for high-temperature CMOS applications.

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