The Amorphous Carbon Layers Deposited by Various Magnetron Sputtering Techniques

Abstract

This study investigates the synthesis and characterization of amorphous carbon (a-C) layers using three magnetron sputtering (MS) techniques: Pulsed MS (PMS), Gas Injection MS (GIMS), and High Power GIMS (HiPGIMS). The primary objective was to understand how these methods influence the sp3/sp2 hybridization ratio, a critical parameter for tailoring the properties of amorphous carbon. Plasma diagnostics via Optical Emission Spectroscopy revealed distinct discharge characteristics, with HiPGIMS exhibiting the highest current density and plasma ionization. Structural and compositional analyses using Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS) demonstrated a clear trend: sp3 content increased significantly from PMS to GIMS to HiPGIMS, reaching up to 50% (Raman) and 39% (XPS). This enhancement is attributed to the higher plasma density and more energetic ion bombardment in HiPGIMS, which promotes the formation of sp3 bonds. Ellipsometric spectroscopy further supported these findings, showing that HiPGIMS produced layers with the widest bandgap, indicative of higher sp3 content. The research highlights the effectiveness of advanced MS techniques, particularly HiPGIMS, in precisely controlling the sp3/sp2 ratio and thereby the electrical, optical, and mechanical properties of a-C layers for various applications.