幾種新型二維原子晶體材料的構(gòu)筑及其結(jié)構(gòu)特性
發(fā)布時間：2018-08-16 19:46
【摘要】：石墨烯,一種由碳原子構(gòu)成的蜂窩狀結(jié)構(gòu),自從在2004年被成功剝離之后就被廣泛研究。單原子層厚度的石墨烯具有很多優(yōu)良特性,例如:超高的載流子遷移率、超高的透光率、室溫下的量子霍爾效應等,使其在電子學、光學、磁學、生物醫(yī)學、催化、儲能和傳感器等領域有巨大的應用潛力,被公認為本世紀的“未來材料”和“革命性材料”。石墨烯的成功激勵人們探索其他類石墨烯二維原子晶體材料,其中碳族二維材料(硅烯、鍺烯和錫烯),非碳族二維材料(硼烯、鉿烯、黑磷、過渡金屬二硫?qū)倩衔锖土降?等也都在各自領域取得了很大成就。本論文主要利用超高真空低溫掃描隧道顯微鏡(STM)、低能電子衍射(LEED)結(jié)合密度泛函理論(DFT)等研究手段探索幾種新型類石墨烯二維原子晶體的生長,并對其結(jié)構(gòu)和電子性質(zhì)進行表征,具體如下:1.單層Mo Se2的邊界結(jié)構(gòu)研究。本工作中報道了利用分子束外延技術(MBE)在Au(111)表面成功構(gòu)筑了規(guī)則邊界形狀的單層Mo Se2島。STM表征揭示了Mo Se2島Mo邊界的高分辨圖像。STS譜線顯示兩種邊界在正偏壓下有明顯不同的電子態(tài)信息。通過DFT計算Mo Se2島的幾種邊界構(gòu)型,實驗中給出Mo Se2島兩種邊界的空間結(jié)構(gòu)(裸露的Se邊和單個Se原子飽和的Mo邊),并且通過分析兩種邊界處的投影態(tài)密度得到不同的電子態(tài)來源于Mo原子的dxz軌道與Se原子的pz軌道耦合。2.二維原子晶體硒化銅的生長、表征及表面修飾。利用一步生長法將Se沉積到貴金屬Cu(111)表面,經(jīng)過后續(xù)加熱處理實現(xiàn)大面積二維單層蜂窩狀貴金屬硒化物的生長。隨著Se沉積量的變化,硒化銅出現(xiàn)兩個不同結(jié)構(gòu):一維條紋結(jié)構(gòu)和六角周期孔洞結(jié)構(gòu)。STM、LEED和DFT研究揭示了兩種結(jié)構(gòu)的內(nèi)在區(qū)別。通過在硒化銅孔洞結(jié)構(gòu)表面沉積原子或分子(Fe,Fe Pc,C60),實現(xiàn)了樣品表面不同位置的選擇性吸附和填充,進而實現(xiàn)硒化銅表面修飾及功能化。3.二維原子晶體硒化銀和二硒化五銀的生長和表征。利用一步生長法將Se沉積到貴金屬Ag(111)表面,經(jīng)過后續(xù)加熱處理實現(xiàn)兩種大面積二維單層貴金屬硒化物的構(gòu)筑。兩種結(jié)構(gòu)的Se原子沉積量不同,制備溫度也不同。其中,單層硒化銀具有蜂窩狀結(jié)構(gòu),可以在室溫下制備,DFT計算顯示其自由單層表面有磁性;制備單層二硒化五銀需要沉積更多的Se原子及一定的退火溫度,LEED顯示其在Ag(111)表面形成(√7×√7)的超結(jié)構(gòu)。4.溴-有機分子氫鍵網(wǎng)格結(jié)構(gòu)的構(gòu)筑。本工作中利用分子束外延技術和掃描隧道顯微鏡表征方法,將非金屬原子(Br)和有機分子(DPA,Dc C6PA,PTCDA)沉積到金屬表面(Ag(111)和Cu(111)),成功構(gòu)筑和表征了大面積二維手性網(wǎng)格結(jié)構(gòu)。在網(wǎng)格結(jié)構(gòu)中,Br原子以最大數(shù)量氫鍵(-C-H···Br)的位置周期分布在有機分子之間。DFT計算給出氫鍵可以穩(wěn)定這種溴-有機分子網(wǎng)格結(jié)構(gòu)。另外,通過改變有機分子與溴原子的比例,實驗上在Ag(111)表面獲得了不同氫鍵網(wǎng)格結(jié)構(gòu)。
[Abstract]:Graphene, a honeycomb structure of carbon atoms, has been widely studied since it was successfully stripped in 2004. Graphene with monatomic thickness has many excellent properties, such as ultra-high carrier mobility, ultra-high transmittance, quantum Hall effect at room temperature, and so on, making it in electronics, optics, magnetism, biomedicine, catalysis, etc. Energy storage and sensors have great application potential and are recognized as "future materials" and "revolutionary materials" in this century. The success of graphene has inspired the exploration of other graphene-like two-dimensional atomic crystal materials, in which two dimensional carbon-group materials (silicene, germane and stannene), non-carbon-group two-dimensional materials (boron, hafnium, black phosphorus, etc.), Transition metal disulfide compounds and hexagonal boron nitride have also made great achievements in their respective fields. In this paper, (STM), low energy electron diffraction (LEED) and density functional theory (DFT) were used to investigate the growth of several novel graphene like two-dimensional atomic crystals, and their structures and electronic properties were characterized. The details are as follows: 1. Boundary structure of monolayer Mo Se2. In this work, the characterization of single layer Mo Se2 island with regular boundary shape on au (111) surface by molecular beam epitaxy (MBE) technique has been reported. The results show that the high resolution image. STS line of Mo Se2 island boundary shows two boundaries under positive bias. There are obviously different electronic state information. Several boundary configurations of Mo Se2 island are calculated by DFT. In the experiment, the spatial structure of two boundaries of Mo Se2 island (bare se edge and single se atom saturated Mo edge) is given. By analyzing the projective density of states at the two boundaries, different electronic states are obtained from the dxz orbits of Mo atoms. Coupling with the pz orbital of se atom. Growth, characterization and Surface Modification of two dimensional Atomic Crystal Copper selenide. Se was deposited on the surface of noble metal Cu (111) by one-step growth method, and the growth of large area two-dimensional honeycomb noble metal selenides was achieved by subsequent heating treatment. With the change of se deposition amount, there are two different structures of copper selenide: one dimensional stripe structure and hexagonal periodic pore structure. STM Led and DFT studies reveal the intrinsic differences between the two structures. The surface modification and functionalization of copper selenide were realized by the deposition of atoms or molecules (Fetife PcC60) on the surface of copper selenide pore structure, and the selective adsorption and filling at different positions on the surface of the sample were realized. Growth and characterization of silver selenide and silver diselenide in two dimensional atomic crystals. Se was deposited on Ag (111) surface of noble metal by one step growth method, and two large area two dimensional monolayer selenides were constructed by subsequent heating treatment. The deposition amount of se atoms in the two structures is different, and the preparation temperature is also different. Among them, silver selenide monolayer has honeycomb structure and can be prepared at room temperature by DFT calculation to show magnetic properties on its free monolayer surface. The preparation of monolayer silver diselenide requires the deposition of more se atoms and a certain annealing temperature to show the superstructure of Ag (111) surface (7 脳 7). Construction of hydrogen bonding network of bromine-organic molecules. In this work, molecular beam epitaxy (MBE) technique and scanning tunneling microscopy (SEM) were used to successfully construct and characterize a large area two-dimensional chiral grid structure by depositing non-metallic atom (Br) and organic molecule (DPA-Dc C6PA-PTCDA) onto metal surface (Ag (111 and Cu (111),). It is shown that the hydrogen bond can stabilize the bromine-organic molecular grid structure in the lattice structure with the maximum number of hydrogen bonds (-C-H Br) distributed periodically between the organic molecules. DFT calculation shows that the hydrogen bond can stabilize the bromine-organic molecular grid structure. In addition, by changing the ratio of organic molecules to bromine atoms, different hydrogen bonding meshes were obtained on Ag (111) surface experimentally.
【學位授予單位】：中國科學院大學(中國科學院物理研究所)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：O48
本文編號：2186995
[Abstract]:Graphene, a honeycomb structure of carbon atoms, has been widely studied since it was successfully stripped in 2004. Graphene with monatomic thickness has many excellent properties, such as ultra-high carrier mobility, ultra-high transmittance, quantum Hall effect at room temperature, and so on, making it in electronics, optics, magnetism, biomedicine, catalysis, etc. Energy storage and sensors have great application potential and are recognized as "future materials" and "revolutionary materials" in this century. The success of graphene has inspired the exploration of other graphene-like two-dimensional atomic crystal materials, in which two dimensional carbon-group materials (silicene, germane and stannene), non-carbon-group two-dimensional materials (boron, hafnium, black phosphorus, etc.), Transition metal disulfide compounds and hexagonal boron nitride have also made great achievements in their respective fields. In this paper, (STM), low energy electron diffraction (LEED) and density functional theory (DFT) were used to investigate the growth of several novel graphene like two-dimensional atomic crystals, and their structures and electronic properties were characterized. The details are as follows: 1. Boundary structure of monolayer Mo Se2. In this work, the characterization of single layer Mo Se2 island with regular boundary shape on au (111) surface by molecular beam epitaxy (MBE) technique has been reported. The results show that the high resolution image. STS line of Mo Se2 island boundary shows two boundaries under positive bias. There are obviously different electronic state information. Several boundary configurations of Mo Se2 island are calculated by DFT. In the experiment, the spatial structure of two boundaries of Mo Se2 island (bare se edge and single se atom saturated Mo edge) is given. By analyzing the projective density of states at the two boundaries, different electronic states are obtained from the dxz orbits of Mo atoms. Coupling with the pz orbital of se atom. Growth, characterization and Surface Modification of two dimensional Atomic Crystal Copper selenide. Se was deposited on the surface of noble metal Cu (111) by one-step growth method, and the growth of large area two-dimensional honeycomb noble metal selenides was achieved by subsequent heating treatment. With the change of se deposition amount, there are two different structures of copper selenide: one dimensional stripe structure and hexagonal periodic pore structure. STM Led and DFT studies reveal the intrinsic differences between the two structures. The surface modification and functionalization of copper selenide were realized by the deposition of atoms or molecules (Fetife PcC60) on the surface of copper selenide pore structure, and the selective adsorption and filling at different positions on the surface of the sample were realized. Growth and characterization of silver selenide and silver diselenide in two dimensional atomic crystals. Se was deposited on Ag (111) surface of noble metal by one step growth method, and two large area two dimensional monolayer selenides were constructed by subsequent heating treatment. The deposition amount of se atoms in the two structures is different, and the preparation temperature is also different. Among them, silver selenide monolayer has honeycomb structure and can be prepared at room temperature by DFT calculation to show magnetic properties on its free monolayer surface. The preparation of monolayer silver diselenide requires the deposition of more se atoms and a certain annealing temperature to show the superstructure of Ag (111) surface (7 脳 7). Construction of hydrogen bonding network of bromine-organic molecules. In this work, molecular beam epitaxy (MBE) technique and scanning tunneling microscopy (SEM) were used to successfully construct and characterize a large area two-dimensional chiral grid structure by depositing non-metallic atom (Br) and organic molecule (DPA-Dc C6PA-PTCDA) onto metal surface (Ag (111 and Cu (111),). It is shown that the hydrogen bond can stabilize the bromine-organic molecular grid structure in the lattice structure with the maximum number of hydrogen bonds (-C-H Br) distributed periodically between the organic molecules. DFT calculation shows that the hydrogen bond can stabilize the bromine-organic molecular grid structure. In addition, by changing the ratio of organic molecules to bromine atoms, different hydrogen bonding meshes were obtained on Ag (111) surface experimentally.
【學位授予單位】：中國科學院大學(中國科學院物理研究所)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：O48
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