CUHL · Controlling Ultrafast Heat in Layered materials

In this project I propose to take advantage of the enormous potential created by the recent material science revolution based on two-dimensional (2D) layered materials, by bringing it to the arena of nanoscale heat transport, where heat transport occurs on ultrafast timescales. This opens up a new research field of controllable ultrafast heat transport in layered materials. In particular, I will take advantage of the myriad of possibilities for miniature material and device design, with unprecedented controllability and versatility, offered by Van der Waals (VdW) heterostructures – stacks of different layered materials assembled on top of each other – and 1D systems of layered materials. Specifically, I will introduce novel device geometries based on VdW heterostructures for passively and actively controlling phonon modes and thermal transport. This will be measured mainly using time-domain thermoreflectance measurements. I will also develop novel time-resolved measurement techniques to follow heat spreading and coupling between different heat carriers: light, phonons, and electrons. These techniques will be mainly based on time-resolved infrared/Raman spectroscopy and photocurrent scanning microscopy. Moreover, I will study one-dimensional layered materials and assess their thermoelectric properties using electrical measurements. And finally, I will combine these results into hybrid devices with a photoactive layer, in order to demonstrate how phonon control allows for tuning of electrical and optoelectronic properties. The results of this project will have an impact on the major research fields of phononics, electronics and photonics, revealing novel physical phenomena. Additionally, the results are likely to be useful towards applications such as thermal management, thermoelectrics, photovoltaics and photodetection.