本文選題：分子器件　切入點：電子輸運　出處：《中南林業(yè)科技大學》2017年碩士論文　論文類型：學位論文

【摘要】：近幾十年來,隨著科技的不斷發(fā)展,以硅材料為基礎制作的電子元器件已經(jīng)越來越無法滿足人們的需求。對于電子元器件的要求已經(jīng)不僅僅限于尺寸方面,在性能方面也需要有進一步的提升。當縮小單個電子元件的尺寸時,不僅制作工藝繁復程度及生產(chǎn)成本都會大幅度上漲,性能方面無法實現(xiàn)質(zhì)的飛躍,還會受到量子力學和熱力學規(guī)律的制約,使硅基材料器件的發(fā)展非常艱難。但是隨著微觀操控技術、微組裝技術、微觀觀測技術和生物物理學的發(fā)展,人們不僅能對有機分子器件的結(jié)構和功能進行觀測和模擬計算,還可以操控納米尺度的單個有機分子,制作有特定功能的分子器件。這些分子器件被認為是慢慢接近尺度極限的傳統(tǒng)電子器件的最合適的替代者。因此在實驗和理論兩方都吸引了越來越多的關注。本論文基于密度泛函理論與非平衡格林函數(shù)相結(jié)合的方法研究幾種有機分子器件的電子輸運性質(zhì)。研究工作包括以下三個方面:(1)錫-酞菁裝置中的自旋過濾,結(jié)果表明,錫-酞菁裝置中自旋向上和自旋向下的投影態(tài)密度的峰值在0.74eV會先向費米能級附近移動,隨著錫原子與酞菁分子距離的增大,峰值逐漸遠離費米能級。在左右電極磁場平行配置中可以觀察到由于結(jié)構重組導致自旋向下過濾轉(zhuǎn)變?yōu)樽孕蛏系倪^濾。在左右電極磁場反平行配置中,在兩個電極的能帶匹配程度將占據(jù)錫-酞菁裝置電子性質(zhì)的主導地位。自旋過濾器類型轉(zhuǎn)換可以通過將錫原子拉離錫-酞菁裝置或翻轉(zhuǎn)一個電極的磁場實現(xiàn)。(2)磁性原子嵌入鋸齒形6,6,12石墨炔納米帶的高自旋過濾效應和半金屬性研究,結(jié)果表明,當磁性原子摻雜在6、6、12-ZGYNRs天然“洞穴”時其能帶會發(fā)生自旋分裂現(xiàn)象。特別是,由于邊緣態(tài)與雜質(zhì)態(tài)耦合導致邊緣納米帶上碳原子的磁矩翻轉(zhuǎn),在鈷摻雜的石墨炔中可觀察到半金屬性。而且在這種摻雜的納米帶內(nèi)發(fā)現(xiàn)在相當寬的偏壓范圍內(nèi)有高自旋過濾效應,為自旋電子學器件的應用提供了一種可能性。(3)研究中心分子與左右電極耦合效應對分子器件的電子輸運特性的影響。主要觀察非那烯分子與石墨烯納米帶所在平面的夾角為0°,30°,60°時電子輸運性質(zhì)的不同的表現(xiàn)。計算結(jié)果表明,隨著偏轉(zhuǎn)角度的增加,該分子器件的電壓-電流特性逐漸變好。
[Abstract]:In recent decades, with the development of science and technology, the electronic components based on silicon material have been unable to meet the needs of people. There is also a need for further improvements in performance. When the size of a single electronic component is reduced, not only will the manufacturing complexity and production costs increase dramatically, but no qualitative leap in performance can be achieved. It will also be constrained by quantum mechanics and thermodynamics, making the development of silicon-based devices very difficult. But with the development of micromanipulation technology, micro-assembly technology, micro-observation technology and biophysics, Not only can the structure and function of organic molecular devices be observed and simulated, but also individual organic molecules can be manipulated on a nanoscale scale. Molecular devices with specific functions are considered to be the most suitable substitutes for traditional electronic devices which are slowly approaching the scale limit. Therefore, both experimental and theoretical aspects have attracted more and more attention. Based on density functional theory (DFT) and nonequilibrium Green's function, the electron transport properties of several organic molecular devices are studied in this paper. The results show that the peak value of projection state density of spin up and down in tin phthalocyanine unit moves first to the Fermi level at 0.74 EV, and the distance between tin atom and phthalocyanine molecule increases with the increase of the distance between tin atom and phthalocyanine molecule. The peak value is gradually away from the Fermi level. In the magnetic field parallel configuration of the left and right electrodes, it can be observed that the spin-down filter changes to the spin-upward filter due to the structural reconfiguration. In the anti-parallel configuration of the left and right electrode magnetic field, The electronic properties of tin phthalocyanine unit will be dominated by the matching degree of energy band between two electrodes. The type conversion of spin filter can be realized by pulling tin atom away from tin phthalocyanine device or flipping the magnetic field of one electrode. Study on the High spin Filtration effect and Semi-metallic Properties of Graphite Nanobelts embedded in Sawtooth 6N 6N 12 Graphite Nanoribbons, The results show that when the magnetic atom is doped in the natural "cave" of 6ZGYNRs, the spin-splitting phenomenon will occur in the energy band, especially, the magnetic moment of carbon atoms in the edge nanosphere is reversed due to the coupling of the edge state and the impurity state. Semi-metallic properties can be observed in cobalt-doped graphite acetylene, and high spin filtering effects are found in such doped nanobelts over a wide bias voltage range, This paper provides a possibility for the application of spin electronic devices.) the influence of coupling effect between central molecule and left and right electrode on electron transport characteristics of molecular devices is studied. When the angle of the plane is 0 擄~ 30 擄~ 60 擄, the properties of electron transport are different. With the increase of deflection angle, the voltage-current characteristics of the molecular device become better.
【學位授予單位】：中南林業(yè)科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O56
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本文編號：1602596