Deposition of MoSe₂ flakes using cyclic selenides.

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Limited availability of volatile organoselenium precursors restricts atomic layer deposition (ALD) of selenium-containing materials.
• Existing synthetic routes for selenium precursors often involve hazardous reagents like sodium or lithium selenides.

Purpose of the Study:

• To expand the portfolio of volatile organoselenium compounds for ALD applications.
• To develop a novel, efficient synthetic method for cyclic silylselenides.
• To evaluate a new precursor for the atomic layer deposition of molybdenum diselenide (MoSe2).

Main Methods:

• Design and synthesis of a series of four-, five-, and six-membered cyclic silylselenides.
• Development of a direct reaction between elemental selenium and chlorosilanes for precursor synthesis.
• Utilizing 2,2,4,4-tetraisopropyl-1,3,2,4-diselenadisiletane as a selenium precursor in a gas-to-solid phase reaction with Molybdenum pentachloride (MoCl5) for ALD.

Main Results:

• Successful synthesis of novel cyclic silylselenides with tunable properties.
• A new, straightforward synthetic route avoiding alkali metal selenides was established.
• The four-membered cyclic silylselenide precursor demonstrated effective ALD of high-purity, out-of-plane oriented 2D MoSe2 flakes.

Conclusions:

• Novel cyclic silylselenides offer a promising alternative to existing organoselenium precursors for ALD.
• The developed synthetic method provides a safer and more direct route to these precursors.
• The four-membered cyclic silylselenide is a well-suited precursor for the ALD of MoSe2.