【摘要】：自從2004年英國科學(xué)家安德烈·蓋姆和康斯坦丁·諾沃肖洛夫從石墨片上成功剝離出石墨烯以來。石墨烯因其獨(dú)特的物理和化學(xué)特性,例如,整數(shù)量子隧道效應(yīng)、超大的理論比面積,優(yōu)異的導(dǎo)電特性和超高的電子遷移率及高的楊氏模量,成為了21世紀(jì)最具潛力的二維納米材料。此外,也正是由于石墨烯的發(fā)現(xiàn),在材料科學(xué)研究領(lǐng)域內(nèi)引起了二維材料研究熱潮。然而,二維材料雖然擁有體材料無法比擬的優(yōu)異特性,但是它們?cè)趯?shí)際應(yīng)用中卻存在著許多限制。以石墨烯為例,石墨烯具有超高的電子遷移率,但是它的帶隙為零,這就限制了它在電子器件工程的應(yīng)用。本論文主要是應(yīng)用基于密度泛函理論的第一性原理方法來理論分析石墨烯和砷烯、石墨烯和二硫化錫范德瓦爾斯異質(zhì)結(jié)以及對(duì)其電子結(jié)構(gòu)的調(diào)制,主要內(nèi)容如下:1)對(duì)砷烯和石墨烯范德瓦爾斯異質(zhì)結(jié)電子結(jié)構(gòu)調(diào)制的研究,首先作為基礎(chǔ)參數(shù)我們研究了石墨烯和砷烯的晶格參數(shù)和電子結(jié)構(gòu),并以此為基礎(chǔ),構(gòu)建了砷烯和石墨烯的范德瓦爾斯異質(zhì)結(jié)。通過對(duì)異質(zhì)結(jié)的計(jì)算分析,我們發(fā)現(xiàn)當(dāng)層間距離從2.8?增加到4.5?,石墨烯狄拉克點(diǎn)的位置和費(fèi)米能級(jí)從砷烯的價(jià)帶頂向?qū)У装l(fā)生轉(zhuǎn)移,且在轉(zhuǎn)移過程中,p型肖特基勢(shì)壘轉(zhuǎn)變?yōu)閚型肖特基勢(shì)壘。通過進(jìn)一步的分析研究,我們還發(fā)現(xiàn)可以通過改變砷烯和石墨烯異質(zhì)結(jié)層間距離,來調(diào)控肖特基接觸的勢(shì)壘高度。此外,我們還構(gòu)建了一種對(duì)稱的三層石墨烯和砷烯范德瓦爾斯異質(zhì)結(jié)結(jié)構(gòu),并簡(jiǎn)單分析了其電子結(jié)構(gòu)和電場(chǎng)條件下對(duì)異質(zhì)結(jié)的電子結(jié)構(gòu)的調(diào)制效應(yīng)。計(jì)算結(jié)果表明,三層異質(zhì)結(jié)中電荷從砷烯轉(zhuǎn)移到了石墨烯,并在界面處進(jìn)行重排。同時(shí),異質(zhì)結(jié)的電子結(jié)構(gòu)在電場(chǎng)的調(diào)節(jié)作用下,變化并不明顯,這也說明對(duì)稱的三層異質(zhì)結(jié)的電子結(jié)構(gòu)對(duì)電場(chǎng)的調(diào)控作用不敏感。2)對(duì)石墨烯和二硫化錫的范德瓦爾斯異質(zhì)結(jié)電子結(jié)構(gòu)調(diào)制的研究,研究發(fā)現(xiàn)層間距離和電場(chǎng)都可以有效的調(diào)節(jié)異質(zhì)結(jié)的電子結(jié)構(gòu)。當(dāng)異質(zhì)結(jié)層間距離增大(2.5?~4.4?)時(shí),肖特基勢(shì)壘的勢(shì)壘有小幅度的減小,基本保持不變,這與范德瓦爾斯力作用效果一致。在外加電場(chǎng)的調(diào)節(jié)作用下,當(dāng)施加負(fù)向電場(chǎng)時(shí),石墨烯的狄拉克點(diǎn)的位置和費(fèi)米能級(jí)從二硫化錫的導(dǎo)帶向價(jià)帶移動(dòng),勢(shì)壘高度有小幅度的增加。當(dāng)施加正向電場(chǎng)時(shí),石墨烯的狄拉克點(diǎn)和費(fèi)米能級(jí)進(jìn)入二硫化錫的導(dǎo)帶,形成歐姆接觸。
[Abstract]:Since British scientists Andre Gheim and Constantine Novoschlov successfully stripped graphene from graphite wafers in 2004. Graphene is due to its unique physical and chemical properties, such as integer quantum tunneling effect, large theoretical specific area, excellent conductivity, high electron mobility and high Young's modulus, It has become the most potential two-dimensional nanomaterials in the 21 st century. In addition, the discovery of graphene has caused a wave of two-dimensional materials research in the field of material science. However, although two-dimensional materials have more excellent properties than bulk materials, they have many limitations in practical application. Taking graphene as an example, graphene has high electron mobility, but its band gap is zero, which limits its application in electronic device engineering. In this paper, the first principle method based on density functional theory is used to analyze graphene and arsenene, graphene and tin disulfide van der Waals heterojunction and their electronic structure modulation. The main contents are as follows: 1) the modulation of the electronic structure of arsenene and graphene van der Waals heterojunction is studied. Firstly, as the basic parameters, we study the lattice parameters and electronic structure of graphene and arsenene. The van der Waals heterojunction of arsenene and graphene was constructed. Through the calculation and analysis of the heterojunction, we find that when the interlayer distance is from 2. 8 to 2. 8? The position of the Dirac point of graphene and the Fermi level are transferred from the bottom of the valence band of arsenene to the bottom of the leading band. During the transfer process, the p-type Schottky barrier changes to the n-type Schottky barrier. Through further analysis we also found that the barrier height of Schottky contact can be regulated by changing the distance between the heterojunction of arsenene and graphene. In addition, we have constructed a symmetric three-layer graphene and arsenene van der Waals heterojunction structure, and analyzed the modulation effects of the electronic structure and electric field on the heterojunction electronic structure. The results show that the charge in the three-layer heterojunction is transferred from arsenene to graphene and rearranged at the interface. At the same time, the electronic structure of heterojunction does not change obviously under the regulation of electric field. It also shows that the electronic structure of symmetric three-layer heterojunction is insensitive to the regulation of electric field. 2) the modulation of electronic structure of graphene and van der Waals heterojunction of tin disulfide is studied. It is found that both interlaminar distance and electric field can effectively regulate the electronic structure of heterojunction. When the interlayer distance between the heterojunction increases (2.5?) The barrier of Schottky barrier decreases by a small margin and remains unchanged, which is consistent with the effect of van der Waals force. When the applied electric field is applied, the position of Dirac point and Fermi level of graphene move from the conduction band of tin disulfide to the valence band, and the barrier height increases slightly. When the positive electric field is applied, the Dirac point and Fermi level of graphene enter the conduction band of tin disulfide and form ohmic contact.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O469

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本文編號(hào)：2334267