Oxygen Plasma-Assisted Bipolar Doping of WSe2 for Reinforcement Learning Synaptic Devices
Baiyan Liu1, Qianqiu Gao2, Yue Wang1
1State Key Laboratory of Precision Measurement Technology and Instruments, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, P. R. China.
ACS Applied Materials & Interfaces
|February 18, 2026
Summary
Researchers developed a new method for controllable bipolar doping in two-dimensional (2D) transition metal dichalcogenides (TMDs) using oxygen plasma. This breakthrough enables advanced applications in neuromorphic computing by precisely tuning material properties.
Area of Science:
- Materials Science
- Nanotechnology
- Semiconductor Physics
Background:
- Controllable bipolar doping in 2D transition metal dichalcogenides (TMDs) is essential for semiconductor information technologies but remains a significant challenge.
- Implementing both controllable doping and nonvolatile carrier modulation in a single fabrication process is critical for neuromorphic computing applications like weight and activation regulation.
Purpose of the Study:
- To propose a facile strategy for achieving tunable bipolar doping in WSe2 using oxygen plasma treatment.
- To demonstrate the integration of this doping strategy into artificial synaptic devices for neuromorphic computing.
Main Methods:
- Fabrication of a WSe2-based structure involving an oxygen plasma-induced oxide layer with tunable surface oxygen vacancies.
- Characterization using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM) to confirm doping mechanisms and surface potential shifts.
- Integration of the fabricated material into transistor-type artificial synaptic devices for neuromorphic applications.
Main Results:
- Precise control over p-type and n-type doping in WSe2 was achieved by regulating oxygen plasma flow rates, leading to stoichiometric WOx and oxygen vacancy-rich WOx formation.
- KPFM measurements confirmed significant surface potential shifts (-99 mV and +66 mV), validating the bipolar doping.
- The artificial synaptic devices exhibited key synaptic behaviors (short-term/long-term plasticity, potentiation, depression) with 64 programmable states and demonstrated adaptive decision-making in a reinforcement learning framework.
- A 6-bit in-memory computing model achieved performance comparable to conventional 32-bit systems.
Conclusions:
- The proposed oxygen plasma-induced strategy offers a versatile approach for achieving controllable bipolar doping and nonvolatile carrier modulation in 2D TMDs.
- This method enables the development of high-performance artificial synaptic devices for efficient neuromorphic computing.
- The work provides a pathway for designing multifunctional hardware for 2D semiconductors, leveraging oxygen vacancy defects for both doping and neuromorphic functionalities.
