Combinatorial Large-Area MoS₂/Anatase-TiO₂ Interface: A Pathway to Emergent Optical and Optoelectronic...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition-metal dichalcogenides (TMDCs) and high-k dielectric transition-metal oxides (TMOs) interfaces are crucial for electronics.
• TMOs impact contact resistance and Fermi-level pinning in metal-TMDC contacts.
• Understanding large-area TMDC/TMO interfaces is essential for device applications.

Purpose of the Study:

• Investigate large-area MoS2/TiO2 interfaces grown by ALD and PLD.
• Analyze the influence of different growth techniques on interface properties.
• Explore the electronic, optical, and photophysical characteristics of these interfaces.

Main Methods:

• Pulsed laser deposition (PLD) and atomic layer deposition (ALD) for TiO2 growth on MoS2.
• X-ray photoelectron spectroscopy (XPS) for doping analysis.
• Density functional theory (DFT) for interface modeling.
• Photoluminescence (PL), transient absorption (TA), and z-scan measurements for optical properties.

Main Results:

• ALD and PLD techniques yield TiO2 layers with distinct crystallinities and morphologies.
• Large-area MoS2/anatase-TiO2 interfaces exhibit p-type doping of MoS2, increasing with TiO2 thickness.
• DFT analysis correlates doping with TiO2 surface termination and defects.
• MoS2/TiO2 (PLD) shows defect-induced midgap levels and enhanced nonlinear optical properties, acting as a saturable absorber.
• MoS2/TiO2 (ALD) presents a relatively defect-free interface.
• MoS2/TiO2 (PLD) demonstrates superior phototransport properties.

Conclusions:

• The growth technique significantly influences the properties of large-area MoS2/TiO2 interfaces.
• MoS2/TiO2 (PLD) interfaces are promising for nonlinear optics and optoelectronic devices, such as p-type phototransistors.
• ALD and PLD offer tunable routes for engineering TMDC/TMO interfaces for advanced applications.