Small Molecule Inhibitor-Modulated Al₂O₃ Atomic Layer Deposition on Monolayer MoS₂ for Controlled Nucleation

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Ultrathin dielectric integration on 2D semiconductors is crucial for beyond-silicon electronics.
• The inert nature of 2D basal planes hinders uniform dielectric nucleation and growth.
• Achieving conformal dielectric layers is essential for device performance and scalability.

Purpose of the Study:

• To develop a novel strategy for uniform dielectric deposition on 2D materials.
• To investigate the use of small molecule inhibitors (SMIs) in atomic layer deposition (ALD).
• To demonstrate improved dielectric uniformity and material integrity using the proposed method.

Main Methods:

• Utilized a small molecule inhibitor (SMI)-modulated thermal atomic layer deposition (ALD) approach.
• Employed acetic acid (HAc) as an SMI for aluminum oxide (Al2O3) ALD on monolayer molybdenum disulfide (1L MoS2).
• Characterized film uniformity using AFM, STEM, EDS, and Raman spectroscopy; investigated nucleation mechanisms with in situ QCM and DFT calculations.

Main Results:

• SMI-modulated ALD achieved nearly continuous ultrathin (∼1.5 nm) Al2O3 films on 1L MoS2 with significantly improved uniformity.
• HAc selectively passivated Al2O3 nuclei, limiting 3D island growth and promoting conformal deposition.
• The process preserved the structural integrity of 1L MoS2, showing minimal strain and doping changes.
• DFT calculations and QCM studies elucidated the inhibitory mechanism of HAc on nucleation and growth.

Conclusions:

• The SMI-modulated ALD strategy provides a broadly applicable framework for controlled dielectric integration on 2D materials.
• This method overcomes the challenge of uniform dielectric nucleation on inert 2D surfaces.
• Enables reliable fabrication of high-quality dielectric layers for advanced nanoelectronic devices.