Nanoscale Thermal Transport Across a GaAs/AlGaAs Interface

As the size of transistors reaches the nanoscale, thermal transport is drastically altered due to the presence of boundaries, which act as a barrier and can decrease the thermal conductivity by orders of magnitude. The possibility of controlling the thermal transport at the nanometer scale requires measurement techniques which can provide adaquate spatial and temporal resolution to map the ultrafast dynamics of phonons. Here, we report the results of measuring phonon-mediated nanoscale thermal transport across a GaAs/AlGaAs quantum well interface and the dependence of the GaAs nanofilm cooling rate on temperature, using a direct and ultrafast lattice probe of ultrafast electron diffraction. The thermal boundary conductance temperature dependence is also extracted using a diffusive model and possible interpretations of these experimental results will be discussed.