Analytical characterization of thin carbon films

Area of Science:

• Materials Science
• Thin Film Technology
• Surface Engineering

Background:

• Carbon-hydrogen (CH(x)) films are utilized in various applications due to their tunable properties.
• Understanding the relationship between deposition parameters, film characteristics, and performance is crucial for optimizing their use.
• Mesh Hollow Cathode Process (MHC) is a technique for depositing thin films.

Purpose of the Study:

• To characterize CH(x) films deposited by MHC with varying thicknesses (~2-20 nm).
• To investigate the correlation between film thickness, wear resistance, and carbon bonding properties.
• To assess the suitability of MHC for producing thin CH(x) overcoats.

Main Methods:

• Deposition of CH(x) films on silicon substrates using Mesh Hollow Cathode Process (MHC).
• Film thickness and deposition rate determined by X-Ray Reflectivity (XRR).
• Correlation of XRR with Secondary Ion Mass Spectrometry (SIMS) sputter depths.
• Wear resistance evaluated using Atomic Force Microscopy (AFM)-based nanoscratching.
• Carbon bonding properties analyzed by Raman spectroscopy.

Main Results:

• X-Ray Reflectivity (XRR) measurements showed good agreement with SIMS sputter depths.
• AFM nanoscratching revealed decreasing wear resistance with decreasing film thickness.
• Raman spectroscopy indicated a more graphitic structure in films thinner than 10 nm.
• Reduced wear resistance in thinner films is attributed to a higher proportion of soft interface zones.

Conclusions:

• The study successfully characterized MHC-deposited CH(x) films across a range of thicknesses.
• Film thickness significantly influences wear resistance and structural properties.
• Thinner CH(x) films (<10 nm) exhibit enhanced graphitic characteristics and reduced wear resistance, likely due to interface effects.