Thermal Resistance Of Micro Nanostructured Interface Measured With Femtosecond Laser Pump-probe Thermal Reflective Method

In this paper,a femtosecond laser pump-probe thermal reflective experimental system has been improved by using a BIBO crystal to make optical frequency double.Meanwhile.By using a low-pass filter reduce the impact of the laser repetition frequency.A CCD camera microscopy is employed to ensure the precise alignment of pump light spot and probe light spot,but also to select the best location on the samples.Ultrashort thermal non-equilibrium transport processes in micro-nano scale is simulation calculated by using MATLAB programming,Laser heating temperat ure distribution of the object under parabolic two-step model and biphasic lag model were obtained.The simulation results of non-equilibrium heat transport process has proved the existence of non-equilibrium phenomenon when metal film is heated by laser,and the effect of electron-phonon coupling factor on the temperature of electron and phonon.Biphasic lag model is used to simulation calculate the temperature distribution in the thickness direction of the samples in different heat-conducting mechanism at a fixed time,and also simulate the temperature evolution of heating surface and a bottom surface with time in different heat-conducting mode.According to the Fourier heat conduction model,the sensitivity of the input parameters?modulation frequency,the laser spot,film thickness,thermal conductivity,interface thermal conductivity?in the date fitting process is analyzed,which provides the basis for the choice of modulation frequency and the size of laser spot when measuring the specific sample.Thermal conductivity and thermal conductivity interface of a variety of materials with two and three different nanostructure layers are measured by using femtosecond laser pump-probe thermal reflective experimental system,and the result correspond to the va lue of existing pertinent literature.Measurement result of the three-layer sample shows,with the increasing of the intermediate layer's thickness of HfO₂ film,the effective interfacial thermal conductivity decreases continuously.It can be concluded for m the measurement result that the interfacial thermal conductivity and thermal conductivity of thin film relate to the intermediate layer's thickness of HfO₂ film...