時域熱反射法研究鈣鈦礦氧化物薄膜及異質(zhì)界面的熱輸運性質(zhì)
發(fā)布時間：2018-07-31 06:15
【摘要】：隨著電子器件集成度的不斷提高,尺寸持續(xù)減小,界面所占比例越來越大,有效地進行熱管理是提高器件效率的重要途徑之一。因此對材料的熱傳輸性質(zhì)的研究顯得尤為重要,尤其是薄膜材料和界面熱輸運性質(zhì)的研究。氧化物以其豐富的組元結構幾乎涵蓋了所有的電學性質(zhì),正如導體、半導體以及絕緣體,其中鈣鈦礦氧化物以其相似的結構及豐富的性質(zhì),非常適合制備異質(zhì)結構,可應用于高頻振蕩器、及復雜邏輯單元等。本論文將對幾種鈣鈦礦氧化物薄膜及其異質(zhì)界面的熱輸運性質(zhì)進行研究。本論文主要內(nèi)容為:利用時域熱反射法對鈣鈦礦氧化物薄膜及異質(zhì)界面熱輸運進行研究,并探討薄膜材料的尺寸效應和界面電學性質(zhì)對界面熱傳輸性質(zhì)的影響。樣品是通過脈沖激光沉積的方法在SrTi03襯底上沉積不同厚度的ReA103(Re=La,Nd,Sm,Gd)薄膜,薄膜厚度以unit cell(u.c.)為單位。主要結論為:(1)通過變溫時域熱反射法對不同厚度和不同批次外延生長的ReA103薄膜熱導率進行測量。結果表明,在厚度相同的情況下,不同批次生長的相同的外延薄膜通過時域熱反射法測量出的熱導率與溫度的關系幾乎相同,表明了時域熱反射測量系統(tǒng)對該體系材料測量的可重復性。在80 u.c.厚度以下,薄膜熱導率表現(xiàn)出了尺寸效應:ReA103薄膜熱導率隨厚度的減小而減小,表明出現(xiàn)聲子的彈道傳輸且隨著薄膜厚度的減小而增強。(2)在以Ti02為終止層的SrTi03襯底上生長的10 u.c.LaA103/SrTi03和10 u.c.NdA103/SrTi03界面存在二維電子氣,常溫下電子濃度達到1.23×1014cm-2和3.29×1013 cm-2;而以SrO為終止層的SrTi03襯底外延生長的樣品異質(zhì)界面表現(xiàn)出高絕緣性;10 u.c.SmAlO3/SrTiO3和10 u.c.NdAlO3/SrTiO3界面表現(xiàn)出絕緣性。通過時域熱反射法對10 u.c.ReAlO3/SrTiO3界面熱傳性能進行研究,結果表明,擁有二維電子氣的界面熱導要高于沒有二維電子氣的界面熱導,且溫度越高,界面熱導相差越大。表明界面二維電子氣的存在對界面熱傳輸有著促進的作用,界面處二維自由電子與聲子的相互作用為界面熱傳導提供了另一傳熱通道。通過計算得出10u.c.LaAlO3/SrTiO3和10u.c.NdAlO3/SrTiO3界面處聲子-電子耦合系數(shù)分別為 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.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O484
，
本文編號：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.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O484
，
本文編號：2154686
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