Nanoscale Mechanisms for Reducing Thermal Boundary Resistance via Ion Bombardment

Given the role of interfaces as the limiting thermal resistance within devices, methods for the reduction of thermal boundary resistance (TBR) are desired. Similarly, with ion bombardment as a prominent method for the doping of semiconductors, the influence of the defects resulting from ion irradiation must be explored.<br/>We present an experimental and computational study wherein we investigate the TBR across defected / pristine crystalline-crystalline interfaces. Experimentally, we use Time Domain Thermoreflectance to measure the TBR across an aluminum / gallium nitride (GaN) interface, where the GaN has been bombarded with various doses of carbon, nitrogen, and gallium ions.<br/>Computationally, we explore a Silicon / Heavy Silicon toy system in which we introduce void / interstitial defect pairs.<br/>We observe a decrease in TBR through the introduction of these defects, both<br/>experimentally and in our simulations. We theorize that this TBR reduction is due to enhanced scattering within the defected material, which serves to assist the transfer of energy between different vibrational populations. This enhancement occurs between bulk and interfacial modes in addition to across the interface, suggesting that the TBR can be engineered by manipulating<br/>just a single material involved. We also note the presence of slight deformation of the lattice between defects, amplifying the effects from relatively-sparse ion-induced defects.