Thermal and Electrical Properties Depending on the Bonding Structure of Amorphous Carbon Thin Films

Abstract

Efficient heat energy management during operation remains a critical challenge in Phase Change Memory (PCM) devices. Reducing the thermal conductivity of electrodes has emerged as a promising strategy to address this issue. Amorphous carbon (a-C) thin films present an attractive option for PCM electrodes due to their intrinsically low thermal conductivity and tunable electrical properties. This study focuses on the development of a-C thin films with optimized electrical and thermal characteristics by controlling the sputtering pressure and conducting post-annealing treatments. Various analytical techniques, including X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and Raman spectroscopy, were employed to investigate the microstructure and composition of the a-C thin films. The results demonstrate that the optimal condition for achieving improved electrical and thermal properties is at the lowest sputtering pressure (2.5 mTorr), which is attributed to the reduced impurity content (specifically oxygen and hydrogen) and denser film structure. Furthermore, post-annealing treatment at 400 °C for 30 min resulted in further improvements in thermal and electrical properties due to the formation of sp² clusters and the reduction of impurities within the film. Consequently, the post-annealed a-C thin film exhibited an outstanding low thermal conductivity of 1.34 W m⁻¹ K⁻¹ and an adequate electrical resistivity of 0.02 Ω cm. The findings of this work provide valuable insights into the underlying mechanisms governing the electrical and thermal properties of a-C thin films, paving the way for the development of energy-efficient PCM devices.

Graphical Abstract