Red Phosphorus by Atomic Layer Deposition

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Elemental red phosphorus (RP) deposition is challenging.
• Atomic Layer Deposition (ALD) offers precise thin-film fabrication.
• Existing methods for RP synthesis are limited.

Purpose of the Study:

• To develop a novel ALD procedure for synthesizing red phosphorus thin films.
• To characterize the properties of the deposited RP films.
• To elucidate the ALD reaction mechanism for elemental phosphorus deposition.

Main Methods:

• Utilized tin tetrachloride and tris(trimethyltin)phosphide as precursors for ALD.
• Determined the optimal ALD temperature window (175–200 °C).
• Employed various characterization techniques (e.g., spectroscopy, microscopy) and density functional theory (DFT) calculations.

Main Results:

• Successfully deposited elemental red phosphorus thin films using ALD.
• Confirmed the self-limiting nature of the process within the identified ALD window.
• Characterized films on diverse substrates (Si/SiO₂, glass, carbon paper) showing pure RP.
• Determined an optical bandgap of ≈1.9 eV, indicating semiconducting behavior.
• DFT calculations proposed a reaction mechanism involving ligand exchange and redox steps.

Conclusions:

• Introduced a new ALD precursor combination for elemental red phosphorus deposition.
• Extended the range of ALD precursors and addressed the lack of elemental P deposition methods.
• The developed method provides a pathway for controlled synthesis of RP thin films for potential applications.