RAMAN THERMOMETRY OF GRAPHENE BASED THERMAL MATERIALS

With the growing demand for high performance computing, we are pushing for higher performance integrated circuits at an ever faster rate. Recent advances in semiconductor production technology sees transistors with a 5 nm process devices being produced for consumer use. This enabled engineers to pack tens of billions of transistors in a package no larger than a fingernail. However, that brings up a problem that we have been long battling against. How can we get rid of the heat produced by these billions of transistors. The current electronic performance is bottle-necked by the ability of the package taking heat away from the transistors. Traditional methods call for mounting the die onto metal using thermal paste or solder, which were good enough to conduct the heat for dissipation with previous technologies. But with the growing power density of modern integrated circuits, that can be problematic. Simply, packages made of metal do not take away the heat fast enough. This thesis investigates thermal properties of graphene based materials. Using the method of Raman thermometry, we can observe the temperature of the materials whilst applying a heat flux at the same time. Using finite-element analysis, our computational model maps our experimental data and extracts the properties of the thermal interface and the material itself. Unlike conventional methods of measuring heat conductivity, raman thermometry is not as limited to the size and continuity of the material. This thesis will be looking at several materials that are difficult to characterize with conventional methods, by observing the temperature of the substrate and the thin film on top. It is also possible for us to calculate the thermal interface resistance. In this thesis, several graphene derived materials will be investigated, such as graphene grown on metal foams, free standing graphene foams and graphene oxide papers. The results of the experiments show the thermal conductivity of the current graphene based foams can have a thermal conductivity of 630 W/mK for the solid portion of the graphene-metal foam structure, but 1.9 W/mK for the bulk material