點缺陷對石墨烯納米材料電學(xué)性能影響的理論研究
發(fā)布時間：2018-08-18 15:26
【摘要】：石墨烯是由碳原子以sp2雜化鍵形成的網(wǎng)狀體系結(jié)構(gòu),因其獨特的物理結(jié)構(gòu)而擁有良好的導(dǎo)電性能。在制備石墨烯的過程中很容易產(chǎn)生缺陷,缺陷和雜質(zhì)的引入在很大程度上擴展了graphene的性能,進一步奠定了graphene在未來作為納米電子器件發(fā)展首選材料的主要位置,而在實驗上已經(jīng)可以做到將graphene刻蝕成準一維的石墨烯納米帶(GNRs),并且實驗上可以利用高能粒子轟擊石墨烯產(chǎn)生缺陷,這也為今后的納米電子器件的發(fā)展提供了堅實的實驗基礎(chǔ),本文主要研究內(nèi)容及結(jié)果有以下兒個方面：(1)采用第一性原理的計算方法研究了鋸齒型GNRs中邊緣結(jié)構(gòu)重構(gòu)形成的兩種不同缺陷結(jié)構(gòu)對材料電子輸運性能的影響,研究發(fā)現(xiàn)兩種缺陷邊緣結(jié)構(gòu)對穩(wěn)定納米尺度位型結(jié)構(gòu)和電子能帶結(jié)構(gòu)具有顯著影響,它使得費米能級發(fā)生移動并引起了共振背散射,兩種邊緣缺陷重構(gòu)均抑制了費米能級附近電子輸運特性并導(dǎo)致不同區(qū)域的電子完全共振背散射,電導(dǎo)的抑制不僅與邊緣缺陷結(jié)構(gòu)的大小有關(guān),它更取決于邊緣缺陷重構(gòu)位型引起的缺陷態(tài)的具體分布和電子能帶的移動。(2)采用第一性原理結(jié)合非平衡格林函數(shù)的計算方法研究了扶手椅型GNRs中雙空位缺陷對材料電子結(jié)構(gòu)和輸運特性的影響,以理想的156個原子的扶手椅型GNRs為原始模型,將不同種類的雙空位缺陷類型引入到納米結(jié)構(gòu)材料中,研究發(fā)現(xiàn)雙空位缺陷的引入對材料的電子結(jié)構(gòu)和輸運特性均產(chǎn)生了一定的影響,它促使費米能級發(fā)生了遷移,其中555-777型缺陷結(jié)構(gòu)相較于5-8-5型缺陷結(jié)構(gòu)其轉(zhuǎn)換能更低,更容易發(fā)生轉(zhuǎn)化。其材料的輸運特性對雙空位缺陷的類型和雙空位缺陷形成的位置有很強的依賴性。(3)采用第一性原理的計算方法研究了Co原子摻雜的扶手椅型GNRs電子結(jié)構(gòu)的影響,以104個原子的扶手椅型GNRs為原始模型,將Co原子利用雙空位取代摻雜引入到模型中,通過改變Co原子的摻雜位置和邊緣C原子的自旋極化設(shè)置計算模擬材料的結(jié)構(gòu)穩(wěn)定性和電學(xué)性能,計算結(jié)果顯示Co原子的引入增強了材料的磁學(xué)性質(zhì),并對材料的電學(xué)性能有一定的影響,能促使材料的費米能級面發(fā)生遷移,增強了材料的導(dǎo)電性能,在材料邊緣C原子上加入自旋極化設(shè)置后能使整個材料趨于平面結(jié)構(gòu),其中自旋平行設(shè)置相較于其他設(shè)置更為穩(wěn)定,材料的結(jié)構(gòu)穩(wěn)定性和電學(xué)性能在很大程度上由Co原子摻雜的位置和邊緣C原子自旋極化設(shè)置決定。
[Abstract]:Graphene is a network of carbon atoms formed by SP2 hybrid bonds. Graphene has good electrical conductivity because of its unique physical structure. Defects are easy to occur in the process of preparing graphene. The introduction of defects and impurities greatly expands the properties of graphene and further lays a foundation for graphene as a nano-electron in the future. Graphene nanoribbons (GNRs) can be etched into graphene nanoribbons, and defects can be produced by bombarding graphene with high-energy particles. This provides a solid experimental basis for the development of nanoelectronic devices in the future. The results are as follows: (1) The effects of two different defect structures formed by edge structure reconstruction on the electronic transport properties of zigzag GNRs are studied by the first-principles method. It is found that the two defect edge structures have significant effects on stable nano-scale potential structure and electronic band structure. Both edge defect reconstruction suppress the electron transport near the Fermi level and lead to the full resonance backscattering of electrons in different regions. The suppression of conductivity depends not only on the size of the edge defect structure, but also on the defect state caused by the reconstructed potential of the edge defect. (2) The effects of double vacancy defects on the electronic structure and transport properties of armchair GNRs were studied by the first-principles method and the non-equilibrium Green's function method. Different types of double vacancy defects were introduced into the armchair GNRs with 156 atoms as the original model. In nanostructured materials, it is found that the introduction of double vacancy defects has a certain effect on the electronic structure and transport properties of the materials, which leads to the transfer of Fermi energy levels. The 555-777 type defect structure has lower conversion energy and is easier to be transformed than the 5-8-5 type defect structure. (3) The influence of Co atom doping on the electronic structure of armchair GNRs was studied by the first-principles method. The armchair GNRs with 104 atoms were used as the original model, and the Co atom was introduced into the model by substituting doping with double vacancies. The doping position of the electron and the spin polarization settings of the edge C atom are calculated to simulate the structural stability and electrical properties of the material. The results show that the introduction of Co atom enhances the magnetic properties of the material and affects the electrical properties of the material to a certain extent. It can promote the migration of the Fermi level surface of the material and enhance the conductivity of the material. The spin polarization settings on the edge C atom of the material can make the whole material tend to a planar structure. The spin parallel settings are more stable than other settings. The structural stability and electrical properties of the material are largely determined by the location of Co atom doping and the spin polarization settings of the edge C atom.
【學(xué)位授予單位】：長江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1
本文編號：2189890
[Abstract]:Graphene is a network of carbon atoms formed by SP2 hybrid bonds. Graphene has good electrical conductivity because of its unique physical structure. Defects are easy to occur in the process of preparing graphene. The introduction of defects and impurities greatly expands the properties of graphene and further lays a foundation for graphene as a nano-electron in the future. Graphene nanoribbons (GNRs) can be etched into graphene nanoribbons, and defects can be produced by bombarding graphene with high-energy particles. This provides a solid experimental basis for the development of nanoelectronic devices in the future. The results are as follows: (1) The effects of two different defect structures formed by edge structure reconstruction on the electronic transport properties of zigzag GNRs are studied by the first-principles method. It is found that the two defect edge structures have significant effects on stable nano-scale potential structure and electronic band structure. Both edge defect reconstruction suppress the electron transport near the Fermi level and lead to the full resonance backscattering of electrons in different regions. The suppression of conductivity depends not only on the size of the edge defect structure, but also on the defect state caused by the reconstructed potential of the edge defect. (2) The effects of double vacancy defects on the electronic structure and transport properties of armchair GNRs were studied by the first-principles method and the non-equilibrium Green's function method. Different types of double vacancy defects were introduced into the armchair GNRs with 156 atoms as the original model. In nanostructured materials, it is found that the introduction of double vacancy defects has a certain effect on the electronic structure and transport properties of the materials, which leads to the transfer of Fermi energy levels. The 555-777 type defect structure has lower conversion energy and is easier to be transformed than the 5-8-5 type defect structure. (3) The influence of Co atom doping on the electronic structure of armchair GNRs was studied by the first-principles method. The armchair GNRs with 104 atoms were used as the original model, and the Co atom was introduced into the model by substituting doping with double vacancies. The doping position of the electron and the spin polarization settings of the edge C atom are calculated to simulate the structural stability and electrical properties of the material. The results show that the introduction of Co atom enhances the magnetic properties of the material and affects the electrical properties of the material to a certain extent. It can promote the migration of the Fermi level surface of the material and enhance the conductivity of the material. The spin polarization settings on the edge C atom of the material can make the whole material tend to a planar structure. The spin parallel settings are more stable than other settings. The structural stability and electrical properties of the material are largely determined by the location of Co atom doping and the spin polarization settings of the edge C atom.
【學(xué)位授予單位】：長江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1
【參考文獻】
相關(guān)期刊論文 前2條
1 王雪梅;劉紅;;鋸齒型石墨烯納米帶的能帶研究[J];物理學(xué)報;2011年04期
2 鄧小清;楊昌虎;張華林;;B/N摻雜對于石墨烯納米片電子輸運的影響[J];物理學(xué)報;2013年18期
，本文編號：2189890
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