Two-step Dual-wavelength Flash Raman Mapping Method for Measuring Thermophysical Properties of Supported 2D Nanomaterials

The thermophysical properties of supported and free-standing nanomaterials would be different due to the substrate effect. To determine the thermophysical properties of supported 2D nanomaterials, this paper developed a two-step dual-wavelength flash Raman (DFR) mapping method. The thermal conductivity of the supported 2D nanomaterial and the thermal contact conductance between the sample and the substrate can be determined by steady-state step. And then the thermal diffusivity of the sample can be characterized by the transient step. Two models are also proposed in this paper. When the substrate temperature rises obviously, a full model considered the substrate temperature distribution is used to decouple the thermal diffusivity, thermal conductivity, and the thermal contact conductance. When the maximum substrate temperature rise is less than 20% of the maximum sample temperature rise, the temperature distribution and variation of the substrate is assumed proportionate to the sample, and then a simplified model can be used to analyse the thermal diffusivity and the other parameters. For the thermal diffusivity, the system error caused by simplifying assumptions is less than 1%, when a dimensionless parameter related to the thermal contact conductance and the thermal conductivity less than 1 and the maximum temperature rise of the substrate less than 15% of that of the supported sample.