Research On Heat Transfer And Regulation Mechanism Of Graphene Nanoribbons And C Omposite Structure In Microelectronics Manufacturing

With the rapid developmet of global technology and society,the functions of electronic devices are becoming more and more integrated and intelligent,and the density of electronic chips continues to increase.Thermal failure has become the most important form of failure of electronic devices.Therefore,the heat dissipation problem of microelectronics manufacturing chips has become a huge bottleneck in the development of micro-nano electronic devices.In recent years,the development of nanomaterials has provided new opportunities for the solution of heat dissipation problems.Graphene is the typical material.Because of its ultra-high thermal conductivity and mechanical strength,it has great potential to become a replacement for silicon materials in the post-Moore law period.Therefore,studying on the heat transport of graphene and graphene nanoribbons at the nanometer scale are extremely important for potential applications in the field of thermal management.This dissertation mainly focuses on the thermal transport properties and regulation of graphene nanoribbons.The main contents are divided into the follows sections:1.The thermal transport and regulation of graphene nanoribbons by vacancy defects-strain were studied.A vacancy defect-strain hybrid mo del was constructed,and the factors affecting the thermal transport and regulation of graphene nanoribbons were studied in conjunction with vacancy defects and strain.The results show that the existence of vacancy defects in the graphene nanoribbons will cause a significant drop in the thermal conductivity of the nanoribbons,and that the vacancy defects with different spatial structures have different effects on the thermal conductivity of the nanoribbons;as the temperature increases,the thermal conductivity of graphene nanoribbons containing different vacancy defects gradually decreases;the position distribution of two point vacancy defects in length direction of the nanoribbons has a great influence on the thermal conductivity of the nanoribbons;as the distance increases,the thermal conductivity of the nanoribbons first decreases and then increases;when the distance reaches about a quarter of the length of the nanoribbons,the thermal conductivity of the nanoribbons is the smallest;in the width direction,with of two points the change of the distance between the two vacancy defects has almost no effect on the thermal conductivity of the nanoribbons;with the increase of defect concentration of the nanoribbon containing point vacancy defects,the thermal conductivity shows a decreasing trend,and eventually tends to a certain value;the regular and random distribution of defects in the armchair and zigzag nanoribbons are differently affected by the defect concentration;with the increase of temperature the thermal conductivity of the graphene nanoribbons decreases under stress;the compressive and tensile strains have different effects on the heat transfer of graphene;with the increase of the defect concentration,the thermal conductivity of the defective graphene nanoribbons of the vacancy defect-strain hybrid model decreases;the influence of thermal conductivity of the nanoribbons is greatest with applying strain on the length direction.2.The regulation effects of graphene nanoribbons with nitrogen doping-vacancy defects on the thermal conductivity of nanoribbons were studied.A hybrid model of nitrogen doping-triangular vacancy defects was constructed,and the influence and regulation of the synergy of nitrogen doping and vacancy defects on the thermal conductivity of graphene nanoribbons were studied,and the thermal rectification effect was found.The results show that the thermal conductivity of the nitrogen-doped graphene nanoribbons decreases with the increase of the doping concentration,and the thermal conductivity of the randomly doped nanoribbons is more affe cted by the doping concentration than the regularly doped nanoribbons.However,the difference ofthermal conductivity between the two doping types is gradually reduced;for triangular single nitrogen doped graphene nanoribbons compared with parallel double nitrogen doped graphene nanoribbons,triangular single nitrogen doped graphene nanoribbons have evidently the rectification effect,and as the temperature rising there is the characteristic of negative rectification with a maximum rectification coefficient of about 12;when nitrogen doping and triangular defects act synergistically on the graphene nanoribbons,It was found that the thermal conductivity of the defective nanoribbons can be improved with the nitrogen doping concentration reaching 0.72%,and the thermal conductivity of the nanoribbons increases by more than 22%,If the doping concentration continues to increase,the thermal conductivity slowly decreases;the thermal conductivity of graphene nanoribbons with higher doped concentration is less affected by temperature;graphene nanoribbons under the synergistic effect of nitrogen doping and triangular defects also exhibit a rectification effect,and the maximum rectification coefficient reaches 18.3.The heat transport properties and regulation of graphene/boron nitride hybrid nanoribbons were studied.The graphene/boron nitride hybrid nanoribbons distributed in the horizontal and vertical directions were constructed to study the influence of the in-plane heterogeneous interface on the thermal conductivity of graphene nanoribbons.The results show that as the temperature increases,there is a great influence on the thermal conductivity of the graphene/boron nitride nanoribbons along the horizontally distributed by the chirality,but there is little effect on the thermal conductivity of graphene/boron nitride nanoribbons along the vertically distributed;for graphene/boron nitride hybrid nanoribbons,as the length and width of the nanoribbons increase respectively,the thermal conductivity also gradually increases;as the hybrid components increase;the thermal conductivity of the graphene/boron nitride hybrid nanoribbons gradually decreases at the same number of interfaces,and when the composition is the same,the thermal conductivity of the horizontally distributed hybrid nanoribbons is greater than that of the vertically distributed nanoribbons;with the number of the interfaces between graphene and boron nitride increasing,the thermal conductivity of the graphene/boron nitride hybrid nanoribbons presents a rapid decline first and then a slow decline.4.Based on the study above,the thermal conductivity of graphene/epoxy composites were studied on the experimental.Three composites of graphene/epoxy,graphene/boron nitride/epoxy and boron nitride/epoxy filled with graphene and boron nitride were prepared by in-situ polymerization.The heat transfer and insulation of composites are studied by controlling the components.The results showthatthe thermal stability of the composites can be improved by graphene filled with epoxy-based composites;as the graphene filler increases,the thermal conductivity of the prepared composites also increases;When the graphene concentration is small,the filler of graphene has little effect on the thermal conductivity of the composite,but as the graphene concentration reaches 0.25wt%,as the graphene concentration increases the thermal conductivity of the composite will first increase rapidly and then decline slowly;for device packaging materials,not only high thermal conductivity,but also high insulation are required;at the same time,the resistivity of the composite is tested;as the concentration of graphene increases,the resistivity of the composite continues to decrease;in order to improve the thermal conductivity and insulation of the composite,the graphene/boron nitride/epoxy composite is prepared by the method of graphene and boron nitride co-doping,and the co-doped composite has the highest thermal conductivity and the resistivity is better than one of graphene/epoxy composite.In this dissertation,based on the bottleneck problem of chip heat dissipation in microelectronics manufacturing,the heat transfer characteristics and mechanism of graphene nanoribbons were studied.The study provided a theoretical basis for the use of graphene in the heat dissipation of micro-nano devices,and realized the regulation of thermal conductivity of graphene and the performance optimization of graphene composites.It provided the reference and guidance for the rational planning of in-plane structure of graphene and the development of thermal management applications in micro-nano chips and devices.