Rare Mononuclear Lithium-Carbene Complex for Atomic Layer Deposition of Lithium Containing Thin Films

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Lithium is crucial for advanced battery technologies.
• Atomic Layer Deposition (ALD) offers precise control over thin film fabrication.
• Developing effective lithium precursors for ALD is essential for next-generation energy storage.

Purpose of the Study:

• Introduce a new mononuclear N-heterocyclic carbene (NHC) stabilized lithium complex, [Li(tBuNHC)(hmds)], as an ALD precursor.
• Characterize the structure and thermal properties of the new lithium complex.
• Demonstrate the efficacy of the precursor in depositing lithium-containing thin films via ALD.

Main Methods:

• Synthesis and structural characterization of [Li(tBuNHC)(hmds)] using single-crystal X-ray diffraction (SC-XRD) and density functional theory (DFT).
• Thermogravimetric analysis (TGA) to evaluate thermal properties and volatility for ALD.
• Atomic Layer Deposition (ALD) trials using the precursor with ozone to deposit LiSixOy films.
• Compositional analysis of deposited films using Rutherford backscattering spectrometry/nuclear reaction analysis (RBS/NRA), X-ray photoelectron spectrometry (XPS), and glow discharge optical emission spectrometry (GD-OES).

Main Results:

• A rare mononuclear lithium complex, [Li(tBuNHC)(hmds)], was successfully synthesized and structurally confirmed.
• The precursor exhibits favorable thermal properties, including a low melting point and clean evaporation, suitable for ALD.
• ALD of LiSixOy films was achieved with a saturated growth per cycle (GPC) of 0.95 Å.
• Compositional analysis confirmed the presence of lithium and silicon in the desired ratios.

Conclusions:

• The novel [Li(tBuNHC)(hmds)] complex is a promising precursor for ALD of lithium-containing materials.
• This work advances the understanding of lithium chemistry and the coordination chemistry of NHC-stabilized lithium complexes.
• The findings contribute to the development of advanced thin film deposition techniques for energy storage applications.