Understanding And Characterizing Thermal Transport In 2d Van Der Waals Nanoelectronics

With novel electronic and optical properties, two-dimensional (2D) materials and their heterogeneous integration have enabled promising electronic and photonic applications. However, significant thermal challenges arise due to numerous van der Waals (vdW) interfaces limiting dissipation of heat generated in the device, induces significant temperature rise, and creates large thermal mismatch, resulting in the degradation of device performance and even failure of the device. The highly localized heat generation during device operation thus becomes a major bottleneck of 2D nanodevice performance. Nevertheless, classical descriptions of heat transfer, i.e., Fourier's Law, become invalid from the microscopic view. Furthermore, it remains challenging to measure heat transport precisely. Advances in the characterization and understanding of heat transfer at the nanoscale are thus needed for practical thermal management of nanoelectronics. Recent theoretical and experimental progress promises more effective nanoelectronics thermal management. On the one hand, atomistic simulation provides great opportunities to investigate fundamental thermal transport processes under ideal conditions by tracking the motion of all atoms. Raman spectroscopy, on the other hand, has been widely applied to detect lattice or molecule vibration on small scales owing to its superior spatial resolution. In this thesis, we leverage the power of atomistic simulation and Raman spectroscopy to understand and characterize thermophysical and thermal transport properties for engineering thermal transport in 2D vdW nanoelectronics. The thesis presents a method of characterizing thermal expansion coefficients for 2D transitional metal dichalcogenide monolayers experimentally and theoretically, and an atomistic simulation framework to predict thermal transport properties, which is used to study vdW binding effects on anisotropic heat transfer and phonon transport through an MoS2-amorphous silica heterostructure toward optimal 2D device heat dissipation. With combined efforts of experiments and simulation, this thesis opens up new avenues to understand, characterize, and engineer thermal transport in 2D vdW nanoelectronics.