Continued miniaturisation of microelectronic components bring about thermal limitations, with devices heating beyond safe levels. Great efforts have therefore been devoted to understanding and controlling thermal transport in nanoscale devices and thermal dynamics around hotspots. Historically, research has considered phonons, the heat carrers in these materials, as particles that can scatter on surfaces, which limits heat dissipation. More recently, efforts to tune the wave properties of these heat carriers have led to studies at ultralow temperatures. As these temperatures are impractical for most applications, materials with which these wave properties can be observed and controlled around room temperature are required.
The recent emergence of ultrathin materials such as graphene, transition metal dichalcogenides (TMDs) and other 2D and layered materials has opened new prospects, not only in electronics, but also optics and filtering. This project aims at engineering and investigating the engineering of thermal transport properties of 2D materials by Focused Ion Beam (FIB) nano-patterning. This approach should provide enhanced control over thermal transport at higher temperatures and benefit both the thermal dissipation field, which is critical for modern electronic components, but also energy harvesting with technologies such as thermoelectricity.
Practically, the project aims at using nano-patterning to control heat transport in 2D and layered materials, such as hotspot study, thermal rectification and phonon dispersion engineering. Nanopatterning modifies the transport properties of thermal carriers –mainly phonons– in two ways. First, it will impact surface scattering of phonons, with scattering events either in random directions of mirror-like reflection, which should enable thermal devices such as thermal lenses and rectification. Second, the wave nature of phonons should play a role in enhancing our control over thermal transport and the thermal properties of these materials. The project will rely on the periodic patterning of holes to (i) make a thermal rectifier in which the heat flux is higher in one dimension than in the opposite direction and (ii) understand the mechanisms governing heat transport at these scales. To achieve this, we will use focus ion beam etching to drill nanoscale holes in the materials.
