【摘要】：石墨烯納米帶(GNRs)因其具有的特殊幾何結(jié)構(gòu)和優(yōu)越的電學性質(zhì),在納米電子學領(lǐng)域具有潛在應用價值,而過渡金屬元素在GNRs上的吸附或摻雜而使GNRs具有更多優(yōu)異的電學磁學特性,因而受到了越來越多的關(guān)注。本文采用基于密度泛函理論的第一性原理,首先對未摻雜的不同自旋極化構(gòu)型下GNRs的電學磁學特性進行計算,接著對Zr吸附、摻雜的GNRs的穩(wěn)定性、電學磁學性質(zhì)、傳輸特性進行了理論計算。主要研究內(nèi)容如下:(1)研究了四種不同自旋極化構(gòu)型的鋸齒形石墨烯納米帶(ZGNRs)的電子結(jié)構(gòu)和傳輸特性。計算結(jié)果顯示,ZGNRs的電子傳輸特性很大程度上受到納米帶邊緣的電子自旋結(jié)構(gòu)的影響。對于平行的自旋組態(tài)(spin-parallel)結(jié)構(gòu)來說,在低偏壓下其電流-電壓是線性關(guān)系;對于反平行的自旋組態(tài)(spin-antiparallel)結(jié)構(gòu),其傳輸特性具有很強的自旋極化依賴性,這樣的性質(zhì)使得該結(jié)構(gòu)可以作為潛在的自旋濾波器;而對于另外兩個自旋組態(tài)結(jié)構(gòu),可以明顯看出其具有半導體特性,在低偏壓時,該結(jié)構(gòu)具有很強的磁致電阻(magneto-resistance,MR)。(2)研究了在扶手椅型石墨烯納米帶(AGNR)中吸附Zr元素的穩(wěn)定性、電子結(jié)構(gòu)以及傳輸特性。研究結(jié)果表明,Zr原子吸附在納米帶邊緣更加穩(wěn)定;AGNR吸附Zr原子后體系均具有鐵磁性(ferromagnetic,FM),具有明顯的金屬性和自旋過濾現(xiàn)象,各體系還出現(xiàn)了明顯的負微分電阻效應。(3)研究了Zr元素在AGNR上不同位置、不同濃度的摻雜的5種Zr-AGNR構(gòu)型,計算了各構(gòu)型的結(jié)構(gòu)穩(wěn)定性、電子結(jié)構(gòu)及傳輸特性。研究結(jié)果表明,各構(gòu)型均表現(xiàn)為非磁性(non-magnetic);在D型摻雜中,Zr原子摻雜在AGNR邊緣使體系更穩(wěn)定,而T型摻雜體系穩(wěn)定性最強;AGNR摻雜Zr元素后體系均具有金屬性:D型摻雜金屬性比T型摻雜強;雙邊同時摻雜的金屬性比單邊摻雜強。各體系的電子正向?qū)ǖ耐ǖ乐饕荶r原子鏈。(4)研究了Zr在鋸齒形石墨烯納米帶中不同位置、不同濃度摻雜的5種Zr-ZGNR的穩(wěn)定性、電子結(jié)構(gòu)及傳輸特性。計算結(jié)果表明不同結(jié)構(gòu)表現(xiàn)出不同的磁性。Zr原子摻雜在ZGNR邊緣使得體系更加穩(wěn)定,各摻雜體系均具有金屬性,且雙邊摻雜金屬性比單邊摻雜強。Z-E2、Z-E1和Z-P1在偏壓較高時出現(xiàn)了微小的負微分電阻現(xiàn)象。各體系的電子正向?qū)ǖ耐ǖ乐饕獮閆r原子鏈。
[Abstract]:Graphene nanobelts (GNRs) have potential applications in the field of nanoelectronics due to their special geometric structure and superior electrical properties. Due to the adsorption or doping of transition metal elements on GNRs, GNRs has more and more excellent electrical magnetic properties, so it has attracted more and more attention. In this paper, the first principle based on density functional theory is used to calculate the electrical magnetic properties of GNRs under different spin polarization configurations without doping, and then the adsorption of Zr, the stability of doped GNRs, and the electrical magnetic properties of GNRs are studied. The transmission characteristics are calculated theoretically. The main contents are as follows: (1) the electronic structure and transport properties of four zigzag graphene nanoribbons (ZGNRs) with different spin-polarized configurations have been investigated. The results show that the electron transport characteristics of ZGNRs are greatly affected by the electron spin structure at the edge of the nanobelts. For parallel spin configuration (spin-parallel) structures, the current-voltage relationship is linear at low bias voltage. For the anti-parallel spin configuration (spin-antiparallel) structure, its transmission characteristics are highly spin polarization-dependent, which makes the structure can be used as a potential spin filter. For the other two spin-configuration structures, it can be seen that they have semiconductor properties. At low bias voltage, the structure has a strong magnetoresistance (magneto-resistance,). MR). (2) the stability, electronic structure and transport properties of Zr elements adsorbed on the armchair graphene nanobelts (AGNR) were investigated. The results show that the adsorption of Zr atoms on the edge of nanobelts is more stable. After AGNR adsorbs Zr atoms, all the systems have ferromagnetism (ferromagnetic,FM), obvious gold properties and spin filtration phenomena. There is also a negative differential resistance effect in each system. (3) the different positions of Zr elements on AGNR have been studied. The structure stability, electronic structure and transport characteristics of five kinds of Zr-AGNR with different concentrations were calculated. The results show that all the configurations are nonmagnetic (non-magnetic), in D-type doping, Zr atom doping at the edge of AGNR makes the system more stable, while T-type doping system has the strongest stability. The gold properties of AGNR doped with Zr elements are stronger than that of T-type doping, and that of bilateral doping is stronger than that of one-sided doping. The electron forward conduction channel of each system is mainly Zr atomic chain. (4) the stability, electronic structure and transport properties of five kinds of Zr-ZGNR doped with different positions and different concentrations of Zr in zigzag graphene nanobelts have been studied. The calculated results show that different structures exhibit different magnetic properties. Doping of Zr atoms on the edge of ZGNR makes the system more stable. All doping systems have gold properties, and the properties of bilateral doping are stronger than that of unilateral doping. Z-E1 and Z-P1 show small negative differential resistance at high bias voltage. The electron forward conduction channel of each system is mainly Zr atomic chain.
【學位授予單位】：廣西大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O469;TB383.1

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