A modified wrinkle-free MoS₂ film transfer method for large area high mobility field-effect transistor

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Achieving wrinkle-free transfer of 2D materials like molybdenum disulfide (MoS₂) is crucial for fabricating high-performance, large-area electronic devices.
• Existing surface-energy-assisted transfer methods can lead to defects such as wrinkles and cracks due to residual droplets.
• These defects hinder the optimal performance and scalability of MoS₂-based electronics.

Purpose of the Study:

• To develop an improved transfer method for chemical vapor deposition (CVD)-synthesized 2D MoS₂ that minimizes wrinkles and cracks.
• To demonstrate the fabrication of large-area MoS₂-based field-effect transistors (FETs) using the novel transfer technique.
• To evaluate the electrical performance of the fabricated FETs, focusing on on/off ratio and carrier mobility.

Main Methods:

• A modified surface-energy-assisted transfer method was developed by adjusting the spreading parameter (S) of residual droplets.
• This modification facilitates the easy removal of liquids from the MoS₂/substrate interface, preventing defect formation.
• Large-area (10 × 10 mm) monolayer MoS₂ films were transferred, and back-gated FET arrays were fabricated using HfO₂ as the high-k gate insulator.

Main Results:

• The modified transfer method successfully produced smooth MoS₂ films without wrinkles or cracks.
• Fabricated MoS₂ FETs exhibited a high on/off ratio of 10⁸.
• The devices achieved a remarkable carrier mobility of up to 118 cm² V^-1 s^-1, representing the highest reported for CVD-synthesized MoS₂ in back-gate transistors.

Conclusions:

• The developed modified surface-energy-assisted transfer method is effective in producing high-quality, large-area 2D MoS₂ films.
• This technique overcomes previous limitations associated with droplet-induced defects during transfer.
• The method provides a viable strategy for fabricating high-performance MoS₂-based electronic devices, particularly FETs, over larger areas.