Atomically thin telluride multiheterostructures: toward spatial modulation of bandgaps

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Lateral multiheterostructures with spatially modulated bandgaps are crucial for high-performance electronic, optoelectronic, and thermoelectric devices.
• Transition metal tellurides offer tunable bandgaps and diverse structural phases, but their synthesis is challenging due to tellurium's low activity and alloy instability.

Purpose of the Study:

• To synthesize and characterize novel lateral multiheterostructures based on tungsten tellurides.
• To investigate the electronic and optoelectronic properties of these materials in field-effect transistors.

Main Methods:

• In situ synthesis of monolayer WSe_2-xTe_2x/WSe_2-yTe_2y (x > y) multiheterostructures using chemical vapor deposition (CVD).
• Photoluminescence analysis and Raman mapping to confirm bandgap modulation.
• Fabrication and characterization of type I and type II field-effect transistors.

Main Results:

• Spatial modulation of the bandgap in the radial direction was confirmed.
• Type I transistors exhibited enhanced ambipolar transport due to low energy bridges.
• Photocurrents in type I transistors were two orders of magnitude higher than in type II transistors due to constructive summation of photovoltaic effects.

Conclusions:

• The synthesized WSe_2-xTe_2x/WSe_2-yTe_2y multiheterostructures offer a new platform for advanced electronic and photonic devices.
• These materials hold potential for applications in broadband light sensing, highly sensitive imaging, and ultrafast optoelectronic integrated circuits.