Study of thermal transport properties of CVD grown graphene membranes: a route to graphene-based thermal sensing device

Since its isolation in 2004, graphene has attracted great interest due to its many extraordinary physical properties. Among them, in recent years, thermal transport in graphene has received increasing attention: the atomic thickness, the lightweight of the carbon atoms and the high degree of crystallinity of the lattice lead to a very high thermal conductivity near room temperature, which makes graphene an extraordinary candidate for thermal management applications in electronic devices [1-5]. In addition theoretical studies reported unprecedented high values of the Seeback coefficient in graphene based devices [6] obtained by tailoring material characteristics and devices design [7]. Despite these extraordinary expected thermal and thermoelectric properties, only few experimental data are still available in the literature, because of experimental challenges, concerning both the complete control of the structural properties of the materials as well as the proper tailoring of the devices characteristics. In this work we will show an integrated approach to the study of the thermal transport properties in graphene, with the final aim to integrate the graphene films directly in the technological design process of testing devices. It will start from a careful control of the structural characteristics of CVD grown graphene, passing trough a detailed structural characterization of the grown membranes by means of SEM and TEM, to arrive to a mapping of the thermal conductivity of the graphene membranes as a function of their structural characteristics. Fig. 1-A shows a TEM high resolution image of a single layer graphene flake, grown by CVD on a Cu layer evaporated on a Si substrate, while Fig. 1-B reports the Thermal Coefficient of Resistance (TCR) of the graphene film on the range 0 - 300 °C.