时域热反射法研究钙钛矿氧化物薄膜及异质界面的热输运性质
发布时间：2018-07-31 06:15
【摘要】：随着电子器件集成度的不断提高,尺寸持续减小,界面所占比例越来越大,有效地进行热管理是提高器件效率的重要途径之一。因此对材料的热传输性质的研究显得尤为重要,尤其是薄膜材料和界面热输运性质的研究。氧化物以其丰富的组元结构几乎涵盖了所有的电学性质,正如导体、半导体以及绝缘体,其中钙钛矿氧化物以其相似的结构及丰富的性质,非常适合制备异质结构,可应用于高频振荡器、及复杂逻辑单元等。本论文将对几种钙钛矿氧化物薄膜及其异质界面的热输运性质进行研究。本论文主要内容为:利用时域热反射法对钙钛矿氧化物薄膜及异质界面热输运进行研究,并探讨薄膜材料的尺寸效应和界面电学性质对界面热传输性质的影响。样品是通过脉冲激光沉积的方法在SrTi03衬底上沉积不同厚度的ReA103(Re=La,Nd,Sm,Gd)薄膜,薄膜厚度以unit cell(u.c.)为单位。主要结论为:(1)通过变温时域热反射法对不同厚度和不同批次外延生长的ReA103薄膜热导率进行测量。结果表明,在厚度相同的情况下,不同批次生长的相同的外延薄膜通过时域热反射法测量出的热导率与温度的关系几乎相同,表明了时域热反射测量系统对该体系材料测量的可重复性。在80 u.c.厚度以下,薄膜热导率表现出了尺寸效应:ReA103薄膜热导率随厚度的减小而减小,表明出现声子的弹道传输且随着薄膜厚度的减小而增强。(2)在以Ti02为终止层的SrTi03衬底上生长的10 u.c.LaA103/SrTi03和10 u.c.NdA103/SrTi03界面存在二维电子气,常温下电子浓度达到1.23×1014cm-2和3.29×1013 cm-2;而以SrO为终止层的SrTi03衬底外延生长的样品异质界面表现出高绝缘性;10 u.c.SmAlO3/SrTiO3和10 u.c.NdAlO3/SrTiO3界面表现出绝缘性。通过时域热反射法对10 u.c.ReAlO3/SrTiO3界面热传性能进行研究,结果表明,拥有二维电子气的界面热导要高于没有二维电子气的界面热导,且温度越高,界面热导相差越大。表明界面二维电子气的存在对界面热传输有着促进的作用,界面处二维自由电子与声子的相互作用为界面热传导提供了另一传热通道。通过计算得出10u.c.LaAlO3/SrTiO3和10u.c.NdAlO3/SrTiO3界面处声子-电子耦合系数分别为 2.09×1014 W/(m3K)和 1.25×1014 W/(m3K)。
[Abstract]:With the continuous improvement of the integration of electronic devices, the size of the device continues to decrease, and the proportion of interface becomes larger and larger. Effective thermal management is one of the important ways to improve the efficiency of the device. Therefore, it is very important to study the thermal transport properties of materials, especially thin film materials and interfacial thermal transport properties. Oxides, with their rich component structures, cover almost all electrical properties, such as conductors, semiconductors, and insulators. Perovskite oxides, with their similar structure and rich properties, are very suitable for preparing heterostructures. It can be used in high frequency oscillator, complex logic unit and so on. In this thesis, the thermal transport properties of perovskite oxide films and their heterogeneous interfaces are investigated. The main contents of this thesis are as follows: the thermal transport between perovskite oxide films and heterogeneous interfaces is studied by time domain thermal reflection method, and the effects of the size effect and interface electrical properties on the interfacial heat transfer properties are discussed. The samples were deposited on SrTi03 substrates by pulsed laser deposition with different thickness of ReA103 (unit cell (u. C.) As a unit. The main conclusions are as follows: (1) the thermal conductivity of ReA103 films grown by different thickness and batch epitaxy is measured by time-domain thermal reflectance method. The results show that under the same thickness, the relationship between the thermal conductivity and temperature of the same epitaxial films grown in different batches by time domain thermal reflection method is almost the same. The repeatability of the time domain thermal reflectance measurement system to the material measurement of the system is demonstrated. At 80u. C. When the thickness is below the thickness, the thermal conductivity of the thin film decreases with the decrease of the thickness. It is shown that the ballistic propagation of phonons increases with the decrease of film thickness. (2) Two-dimensional electron gas exists at the interface of 10 u.c.LaA103/SrTi03 and 10 u.c.NdA103/SrTi03 grown on SrTi03 substrate with Ti02 as the termination layer. The electron concentration reaches 1.23 脳 1014cm-2 and 3.29 脳 1013 cm-2 at room temperature, while the heterostructure interface grown on SrTi03 substrate with SrO as termination layer exhibits high insulation at 10 u.c.SmAlO3/SrTiO3 and 10 u.c.NdAlO3/SrTiO3 interfaces. The thermal conductivity at the interface of 10 u.c.ReAlO3/SrTiO3 is studied by time-domain thermal reflection method. The results show that the interfacial thermal conductivity of the interface with two-dimensional electron gas is higher than that of the interface without two-dimensional electron gas, and the higher the temperature, the greater the difference of interface thermal conductivity. It is shown that the existence of two-dimensional electron gas at the interface promotes the heat transfer at the interface, and the interaction between the two-dimensional free electron and the phonon at the interface provides another heat transfer channel for the interface heat conduction. The phonon-electron coupling coefficients at the 10u.c.LaAlO3/SrTiO3 and 10u.c.NdAlO3/SrTiO3 interfaces are calculated to be 2.09 脳 1014 W / (m3K) and 1.25 脳 1014 W / (m3K), respectively.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O484
，
本文编号：2154686
[Abstract]:With the continuous improvement of the integration of electronic devices, the size of the device continues to decrease, and the proportion of interface becomes larger and larger. Effective thermal management is one of the important ways to improve the efficiency of the device. Therefore, it is very important to study the thermal transport properties of materials, especially thin film materials and interfacial thermal transport properties. Oxides, with their rich component structures, cover almost all electrical properties, such as conductors, semiconductors, and insulators. Perovskite oxides, with their similar structure and rich properties, are very suitable for preparing heterostructures. It can be used in high frequency oscillator, complex logic unit and so on. In this thesis, the thermal transport properties of perovskite oxide films and their heterogeneous interfaces are investigated. The main contents of this thesis are as follows: the thermal transport between perovskite oxide films and heterogeneous interfaces is studied by time domain thermal reflection method, and the effects of the size effect and interface electrical properties on the interfacial heat transfer properties are discussed. The samples were deposited on SrTi03 substrates by pulsed laser deposition with different thickness of ReA103 (unit cell (u. C.) As a unit. The main conclusions are as follows: (1) the thermal conductivity of ReA103 films grown by different thickness and batch epitaxy is measured by time-domain thermal reflectance method. The results show that under the same thickness, the relationship between the thermal conductivity and temperature of the same epitaxial films grown in different batches by time domain thermal reflection method is almost the same. The repeatability of the time domain thermal reflectance measurement system to the material measurement of the system is demonstrated. At 80u. C. When the thickness is below the thickness, the thermal conductivity of the thin film decreases with the decrease of the thickness. It is shown that the ballistic propagation of phonons increases with the decrease of film thickness. (2) Two-dimensional electron gas exists at the interface of 10 u.c.LaA103/SrTi03 and 10 u.c.NdA103/SrTi03 grown on SrTi03 substrate with Ti02 as the termination layer. The electron concentration reaches 1.23 脳 1014cm-2 and 3.29 脳 1013 cm-2 at room temperature, while the heterostructure interface grown on SrTi03 substrate with SrO as termination layer exhibits high insulation at 10 u.c.SmAlO3/SrTiO3 and 10 u.c.NdAlO3/SrTiO3 interfaces. The thermal conductivity at the interface of 10 u.c.ReAlO3/SrTiO3 is studied by time-domain thermal reflection method. The results show that the interfacial thermal conductivity of the interface with two-dimensional electron gas is higher than that of the interface without two-dimensional electron gas, and the higher the temperature, the greater the difference of interface thermal conductivity. It is shown that the existence of two-dimensional electron gas at the interface promotes the heat transfer at the interface, and the interaction between the two-dimensional free electron and the phonon at the interface provides another heat transfer channel for the interface heat conduction. The phonon-electron coupling coefficients at the 10u.c.LaAlO3/SrTiO3 and 10u.c.NdAlO3/SrTiO3 interfaces are calculated to be 2.09 脳 1014 W / (m3K) and 1.25 脳 1014 W / (m3K), respectively.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O484
，
本文编号：2154686
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