Granular metals with SiN_xdielectrics.

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Nanoscale interface phenomena, including band bending and secondary phase formation, are vital for optimizing electronic devices.
• In granular metal (GM) systems, where metal nanoparticles are dispersed in an insulating matrix, interface effects are often overlooked.
• Commonly used oxide insulators in GMs can lead to undesirable secondary phase formation.

Purpose of the Study:

• To investigate silicon nitride (SiN) as an alternative insulating matrix for granular metals, particularly for high-temperature applications.
• To evaluate the role of secondary phase formation at metal-insulator interfaces in GMs.
• To compare the interface properties and electrical conductivity of cobalt-silicon nitride (Co-SiN) and molybdenum-silicon nitride (Mo-SiN) GMs.

Main Methods:

• Utilized a combination of X-ray photoemission spectroscopy (XPS) and electrical transport studies.
• Investigated the formation of metal silicides and nitrides at the nanoscale interfaces.
• Compared the conductivity of Mo-SiN and Co-SiN granular metal systems.

Main Results:

• Mo-SiN GMs exhibited significantly reduced metal-silicide formation and orders-of-magnitude lower conductivity compared to Co-SiN GMs in the tunneling-dominated insulating regime.
• XPS measurements confirmed that metal-silicide and metal-nitride formation are controllable in Mo-SiN systems.
• Silicon nitride (SiN) proves to be a promising alternative to metal oxides, especially for metals prone to oxidation.

Conclusions:

• Silicon nitride (SiN) is an effective alternative insulator for granular metals, mitigating secondary phase formation and enabling tunable conductivity.
• Mo-SiN GMs offer reduced interfacial reactions, making them suitable for applications requiring stable high-temperature performance.
• The use of SiN opens pathways for creating novel metal-nitride nanostructures for plasmonics, optics, and sensing applications.