UV light modulated synaptic behavior of MoTe₂/BN heterostructure.

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Neuroscience

Background:

• Neuromorphic computing systems aim to overcome limitations of the von Neumann architecture using hardware-based synaptic devices.
• Current three-terminal synaptic devices rely on floating gates or charge trapping layers for stable conductance modulation, increasing complexity and thickness.

Purpose of the Study:

• To report a novel three-terminal synaptic device based on a two-dimensional molybdenum ditelluride (MoTe₂)/hexagonal boron nitride (hBN) heterostructure.
• To demonstrate a photo-induced doping method for stable and prominent conductance modulation of the MoTe₂ channel.
• To explore an alternative synaptic configuration free of floating gates and charge trapping layers.

Main Methods:

• Fabrication of a heterostructure device using MoTe₂ and hBN.
• Utilizing ultraviolet (UV) light to induce electron migration and photo-doping in the MoTe₂ channel via hBN defect states.
• Characterization of device performance, including conductance modulation, short/long-term plasticity, and resistance ratio under varying UV conditions.

Main Results:

• The MoTe₂/hBN heterostructure enables stable conductance modulation through UV-induced photo-doping, eliminating the need for floating gates or charge trapping layers.
• The device exhibits both short- and long-term plasticity, tunable by UV illumination, and offers additional control via UV wavelength and intensity.
• Photo-induced doping allows bidirectional modulation (n-doping and p-doping), achieving a large high/low resistance ratio for multi-level storage and implementing synaptic potentiation and depression.

Conclusions:

• This work presents a novel three-terminal synaptic device configuration that simplifies fabrication and reduces thickness.
• The photo-induced doping mechanism offers a new pathway for realizing advanced synaptic functions and efficient neuromorphic hardware.
• The developed device architecture may inspire further research into alternative electrical synapse mechanisms.