Research On The Preparation And Properties Of Vanadium Dioxide Thin Films On Van Der Waals Substrate

Vanadium dioxide(VO₂)is a binary metal oxide phase-change material.When VO₂undergoes a metal-insulation transition(MIT),the electrical,optical,thermal,and magnetic properties of VO₂ will also change dramatically as the phase transition occurs.In addition,the phase transition of VO₂ has good reversibility,and the phase transition temperature of VO₂ is 68?(340 K).Among many oxide phase-change materials,the phase change temperature of VO2 is the closest to room temperature.In recent years,with the development of the artificial intelligence era and people's pursuit of a better life,the current traditional microelectronic devices can no longer meet people's expectations,which poses new challenges for researchers.At present,flexible microelectronic devices are considered to be a feasible solution.The most direct way of this solution is to make traditional devices flexible and bring the good performance of traditional microelectronics to flexible microelectronic devices.In view of the flexibility of VO₂ thin films,the transfer process can be used to transfer VO₂ thin films from a traditional substrate to a flexible substrate,but the process is unstable,difficult to operate.So it is difficult to manufacture on a large scale;in addition,pulsed laser deposition(PLD)can also be used to grow VO₂ thin film on mica and then mechanically stripped.However,PLD is expensive and requires equipment environment,resulting in high production cost and difficult to achieve industrialization.At the same time,after the flexibility and miniaturization of electronic devices,the power consumption and heat dissipation of the devices will become a new challenge.At this time,the thermal performance of the materials that make up the device will become an important concern,especially the thermal conductivity of the material,which is closely related to heat dissipation.This requires researchers to measure the true thermal conductivity of the material as much as possible.In response to the above problems,this paper introduces a seed layer and uses polymer assisted deposition(PAD)to grow better quality VO₂ thin films on fluorine mica,and conducts research on the transient thermal properties of the VO₂ thin films before and after the phase transition.To this end,this paper introduces a method:first dilutes the original concentration of the precursor solution to 20%of the original concentration,spin-coating on the fluorine mica and annealing at high temperature to form a seed layer,and then spin-coating the original concentration of the precursor solution on the seed layer and high temperature annealing is performed to obtain VO₂ thin films.Then use XRD,AFM,SEM,XPS,Raman spectroscopy and other characterization methods to characterize the VO₂ thin films,and then measure the electrical properties of the VO₂ thin films grown without introducing the seed layer and introducing the seed layer,and compare theirs difference.Finally,it is known that the introduction of the seed layer can improve the quality of the VO₂ thin films.In order to explore the transient thermal properties of the VO₂ thin films before and after the phase transition,four groups of VO₂thin films with different thicknesses were obtained through multiple spin-coating of the precursor solution and high-temperature annealing and crystallization.First,measure the phase transition temperature of 4 groups of VO₂ thin films to determine the test temperature of transient thermal performance.Then the thermal diffusion curve of the thermal properties of the VO₂ thin films was measured and the results were normalized and fitted to obtain the thermal conductivity of VO₂ before and after the phase change.Finally,a brief discussion on the heat transfer mode of the metal phase VO₂ thin films is given.In the research of introducing VO₂ seed layer and using PAD method to grow VO₂thin films,discover that the introduction of VO₂ seed layer can significantly increase the grain size of VO₂ thin films and reduce defects,promote the layered growth of VO₂ thin films,and improve the performance of VO₂ thin films.The electrical properties are conducive to obtaining better quality VO₂ thin films.In the transient thermal study of the VO₂ thin films before and after the phase transition,when the thickness of the VO₂ thin films exceeds 100 nm,mica with lower thermal conductivity than sapphire can be used as the substrate,and the metal-free reflector time domain thermal reflectance method can be used for measurement The thermal conductivity of the VO₂ thin films,which can avoid the influence of the interface thermal resistance between the VO₂ thin films and the metal reflective layer,and get a result closer to the actual thermal conductivity of the VO₂ thin films itself.At the same time,the software Thermal Analysis for Thin can also be used directly films read the thermal conductivity.