Thermal Conductivity Manipulation through Structural Modification with Ion Beams

Doping through ion implantation has long been used to tailor the band structure and electrical properties of materials for use in computer and semiconductor technologies. While the electronic properties of ion implanted materials remains a field of active research, there are notably fewer works that focus on how it effects the transfer of heat through the material. The process of ion irradiation, by its nature, introduces defects into a material lattice which act as scattering sites for phonons, thereby reducing the thermal conductivity. However, nuances of the implantation process such as ion mass, ion energy, and the nature of the damage and residual strain have a significant impact upon the thermal response of the implanted material. The following work examines these topics through experimental investigation of the thermal conductivity of irradiated materials. Specifically, this dissertation comprises several case studies which focus upon the modification of thermal conductivity via ion implantation of silicon and carbon material systems. Insight from these studies demonstrates how ion implantation can be utilized as a powerful tool for enabling deeper understanding of phonon scattering physics, and provides avenues for the manipulation of thermal properties through selective implantation techniques.