Thermal Anisotropy And Interfacial Heat Transfer Study Of Ti₃C₂T_x Thin Films

MXene is a new family of 2-D material series,and titanium carbide（Ti₃C₂T_x）is the most studied and widely used material in MXene,which has attracted much attention because of its excellent electrical and optical properties.However,the thermal transport properties of Ti₃C₂T_x ,especially thermal conductivity anisotropy and interfacial heat transfer,have not been completely investigated.To deal with the significant scale effect of Ti₃C₂T_x thin film in thermal measurement studies,this paper builds a transient electrothermal experimental platform for thin films according to the 1-D thermal measurement method to study the in-plane thermal conductivity of independent Ti₃C₂T_x thin films.The transient electrothermal method is a transient thermal measurement method that uses a step current to heat up the film from in-plane direction,characterized by the fact that the heat flow direction is only related to the in-plane temperature distribution.In addition,to deal with the research difficulties of Ti₃C₂T_x thin film in the thickness of only micrometer level and the measurement signal is extremely low,this paper builds a frequency domain photothermal experimental platform.The photothermal method,developed from photoacoustic technology,is a thermal measurement method by comparing the phase shift of the radiation signal of thin films under monochromatic square wave laser heating,also a thermal measurement technique that changes the thermal diffusion depth by adjusting the laser frequency.The photothermal platform was validated to measure standard samples with an accuracy of less than 15%.It is found that Ti₃C₂T_x thin film has a more prominent thermal conductivity anisotropy among 2-D materials.The in-plane thermal conductivity of Ti₃C₂T_x films was 19.5 W/m-K at 300.8 K.As the temperature increased to 335.5 K,the thermal conductivity increased by 16%overall.In contrast,the overall value of out-of-plane thermal conductivity is lower,0.88 W/m-K3 at 326 K,which is more than twenty times different from in-plane.And the out-of-plane thermal conductivity decreases by 36.7%as the temperature increases to 344K.The appearance of this thermal conductivity anisotropy is related to the size effect,stacking method,cavitation distribution,etc.In the field of heat conduction,not only the thermal conductivity of the material itself is an important research direction,but also the interfacial heat transfer between different materials is very important.To solve the problem that 2-D materials are difficult to dissipate heat in devices and prone to local hot spots,this paper prepares Ti₃C₂T_x /Si substrate samples in experiments based on both photothermal experiments and numerical simulations,and measures the thermal resistance value of Ti₃C₂T_x /Si interface as 4.53×10^-7m²-K/W.In addition,with the means of Comsol simulation,a photodetector micro-module model is established and analyzed in actual device applications,the temperature field at the thermal contact interface,proving that both the thermal conductivity anisotropy of the sample itself and the interfacial heat transfer are essential to improve the performance of high precision and high performance electronic devices.In this paper,the thermal conductivity anisotropy of Ti₃C₂T_x films is investigated thoroughly from the Ti₃C₂T_x films themselves,and the interfacial problems of Ti₃C₂T_x /Si substrates are explored through experiments and simulations to explore the interfacial problems of Ti₃C₂T_x and Si substrates in device applications,providing heat transfer-related guidance for further applications of Ti₃C₂T_x and even 2-D materials in microelectronic devices.