Sulfur-Doped Black Phosphorus Field-Effect Transistors with Enhanced Stability

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Black phosphorus (BP) is a promising 2D material for electronic and optoelectronic devices due to its tunable band gap and high charge-carrier mobility.
• The practical application of BP is hindered by its poor stability and rapid degradation under ambient conditions.

Purpose of the Study:

• To investigate the effectiveness of sulfur (S) doping in enhancing the ambient stability of black phosphorus.
• To fabricate and characterize S-doped BP field-effect transistors (FETs) and evaluate their performance and stability.

Main Methods:

• Fabrication of few-layer S-doped BP FETs.
• Ambient stability testing of S-doped BP FETs over 21 days.
• Characterization using atomic force microscopy (AFM) for surface morphology, thickness, and roughness.
• First-principles calculations to understand the mechanism of stability enhancement.

Main Results:

• S-doped BP FETs exhibited significantly improved stability under ambient conditions compared to undoped BP.
• A representative S-doped BP FET retained 77.4% of its initial charge-carrier mobility (decreasing from 607 to 470 cm² V^-1 s^-1) after 21 days.
• A large on/off ratio of approximately 10³ was maintained.
• AFM analysis confirmed a lower degradation rate for S-doped BP.
• First-principles calculations revealed that S doping shifts the conduction band minimum below the redox potential of O₂/O₂^-, enhancing stability.

Conclusions:

• Sulfur doping is an effective strategy to suppress the degradation of black phosphorus.
• S-doped BP demonstrates enhanced stability and retains high performance, making it more suitable for practical electronic and optoelectronic applications.