本文關(guān)鍵詞：類石墨烯二維異質(zhì)結(jié)構(gòu)和單原子納米鏈的電子輸運(yùn)性質(zhì)　出處：《山東大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 異質(zhì)結(jié)構(gòu) 二維納米材料 納米鏈 電子輸運(yùn) 第一性原理

【摘要】：隨著電路的集成化和電子元器件的小型化,納米電子器件以其獨(dú)特的性能越來越受到人們的關(guān)注。納米異質(zhì)結(jié)構(gòu)是由至少兩種不同的納米材料組成,因其可以改進(jìn)材料的性能從而滿足實(shí)際應(yīng)用需求,成為了當(dāng)下研究的熱點(diǎn)。目前,隨著對納米電子器件研究的深入,對其電子輸運(yùn)性質(zhì)等內(nèi)在機(jī)理的研究成為了人們關(guān)注的焦點(diǎn)。本論文利用利用第一性原理和非平衡格林函數(shù)的方法,研究了二維納米異質(zhì)結(jié)構(gòu)和單原子納米鏈的電子輸運(yùn)性質(zhì),揭示了如何通過摻雜和構(gòu)造異質(zhì)結(jié)構(gòu)改變電子輸運(yùn)性質(zhì)。全文的主要內(nèi)容如下:(1)研究了摻雜三角形氮化硼石墨烯納米帶的自旋磁性。發(fā)現(xiàn)在不考慮自旋極化時(shí),器件是金屬性,而且隨著三角形氮化硼納米片尺寸的增大,其電子輸運(yùn)能力逐漸被抑制。考慮自旋極化后,器件轉(zhuǎn)變?yōu)榘雽?dǎo)體特性,并且通過改變?nèi)切蔚鸺{米片尺寸的大小,可以調(diào)控其自旋極化性質(zhì)。重要的是,在T_B_15N_21中,出現(xiàn)了雙磁性半導(dǎo)體性質(zhì),并且擁有很高的電子輸運(yùn)能力和接近100%的自旋過濾效率,而具有相同氮化硼原子數(shù)的矩形氮化硼R_3BNNR沒有出現(xiàn)雙磁性半導(dǎo)體性質(zhì),并且其電子輸運(yùn)能力被限制。與摻雜三角形氮化硼的石墨烯納米帶類似,三角形空位的V_B(15)N(21)也出現(xiàn)了雙磁性半導(dǎo)體性質(zhì),并且也有很高的自旋過濾效率,但是其電子輸運(yùn)能力和穩(wěn)定性都不如摻雜三角形氮化硼的T_B_(15)N_(21)。(2)構(gòu)造了平行和垂直排列拼接的MoS_2NRs和WS_2NR_s異質(zhì)結(jié)構(gòu)。研究了這些異質(zhì)結(jié)構(gòu)的電子輸運(yùn)性質(zhì),發(fā)現(xiàn)所有的異質(zhì)結(jié)構(gòu)都表現(xiàn)出直接帶隙半導(dǎo)體的特性,這意味著這些異質(zhì)結(jié)構(gòu)可以用于光電子器件。隨著WS_2NR_s納米帶的增加,帶隙微弱較小,導(dǎo)致了電流的快速增長和更高的峰值電流。此外,隨著WS_2NR_s納米帶的增加,對于M(na)雙電極器件,負(fù)微分電阻效應(yīng)得到一定提高,而M(nz)雙電極器件的負(fù)微分電阻效應(yīng)的變化卻表現(xiàn)出相反的趨勢,但是電流增長更快,峰值電流更高,這說明垂直拼接的M(na)雙電極器件在邏輯電路中有更好的應(yīng)用前景。特別指出的是,鎢原子在邊界的M(edge)雙電極器件不僅有很顯著的負(fù)微分電阻效應(yīng),而且在低壓區(qū)還有很高的峰值電流,其邏輯電路的應(yīng)用性能最好。(3)研究了扶手椅型和鋸齒型MoS_2NRs/WS_2NR_s異質(zhì)結(jié)構(gòu)的電子輸運(yùn)性質(zhì)。我們發(fā)現(xiàn)所有扶手椅型MoS_2NRs/WS_2NR_s異質(zhì)結(jié)構(gòu)都表現(xiàn)出電流的整流效應(yīng),意味著這類結(jié)構(gòu)可以應(yīng)用于pn結(jié)分子整流器。隨著異質(zhì)結(jié)構(gòu)中WS_2納米帶長度的增加,整流效應(yīng)被抑制,這是由于在正壓區(qū)電子透射峰下降導(dǎo)致的。此外,在正壓區(qū)和負(fù)壓區(qū)都觀察到了負(fù)微分電阻效應(yīng),并且可以通過改變WS_2納米帶長度來調(diào)節(jié)負(fù)微分電阻效應(yīng)的強(qiáng)弱。對于所有鋸齒型MoS_2NRs/WS_2NR_s異質(zhì)結(jié)構(gòu),除了負(fù)微分電阻效應(yīng),也觀察到了自旋過濾效應(yīng),意味著這類異質(zhì)結(jié)構(gòu)可以應(yīng)用于自旋電子器件。隨著異質(zhì)結(jié)構(gòu)中WS_2納米帶長度的增加,自旋過濾效率升高,zMoS2-5zWS_2NR_s達(dá)到60%。當(dāng)連接WS_2納米帶電極時(shí),無論是否考慮自旋極化,MoS_2NRs/WS_2NR_s異質(zhì)結(jié)構(gòu)都表現(xiàn)出比較好的電子輸運(yùn)性質(zhì),如高的自旋過濾效率和較好的負(fù)微分電阻效應(yīng)。(4)研究了碳納米鏈,氮化硼納米鏈,和納米鏈異質(zhì)結(jié)構(gòu)的電子輸運(yùn)性質(zhì)。我們發(fā)現(xiàn)所有的單原子鏈都表現(xiàn)出奇偶效應(yīng),而且隨著長度的增加,輸運(yùn)性質(zhì)被抑制。在偶數(shù)的單原子鏈中,除了純的碳鏈外,都出現(xiàn)了電流的整流效應(yīng),我們發(fā)現(xiàn)整流效應(yīng)是由非對稱的電子結(jié)構(gòu)引起的。此外,傾斜的碳鏈幾乎對輸運(yùn)性質(zhì)沒有影響,然而雙碳鏈的傳輸能力可以提高兩倍。當(dāng)考慮自旋極化后,所有的結(jié)構(gòu)都是磁性半導(dǎo)體,而且自旋過濾效應(yīng)呈現(xiàn)奇偶性。重要的是,鏈通道的態(tài)密度決定了電子透射率譜和器件的電流電壓特性曲線。電流電壓曲線的變化,可以很好地用平衡態(tài)下的電子透射率譜解釋,費(fèi)米能級附近和遠(yuǎn)離費(fèi)米能級的透射峰很好地對應(yīng)了低壓區(qū)和高壓區(qū)的電流。此外,對于單原子鏈異質(zhì)結(jié)構(gòu),通過改變碳原子和氮化硼的原子個(gè)數(shù),其電學(xué)特性可以有效地調(diào)節(jié)。CnBNm異質(zhì)結(jié)構(gòu)電流的整流效應(yīng)彼此之間類似,表現(xiàn)出正向和反向的整流現(xiàn)象,而且隨著碳原子數(shù)的增加,電流的傳輸能力提升一倍。特別是當(dāng)碳原子在鏈通道和石墨烯納米帶連接處時(shí),其電子輸運(yùn)能力得到很大地提高,如電流的傳輸能力和整流效應(yīng)。然而當(dāng)考慮自旋極化后,碳鏈在一側(cè)時(shí)的自旋過濾效應(yīng)更好。本文的研究內(nèi)容對于深入理解二維納米異質(zhì)結(jié)構(gòu)和單原子納米鏈的電子輸運(yùn)性質(zhì)具有重要意義,為設(shè)計(jì)和開發(fā)高性能的納米電子器件提供了理論指導(dǎo)。
[Abstract]:With the miniaturization of integrated circuit and electronic components, nano electronic devices with its unique performance more and more attention. The nano heterostructure is composed of at least two different nano materials, because of its performance can be improved materials to meet the actual application requirements, has become the focus of current research. At present, with the study of nano electronic devices in-depth research on the electronic transport properties of the internal mechanism has become the focus of attention. This paper use the first principle method and non equilibrium Green function, two Vinami heterostructures and single atomic chain of nano electron transport properties, reveals how by doping and the structure of heterogeneous structure change electron transport properties. The main contents of this paper are as follows: (1) study the triangle doped boron nitride graphene nanoribbons. Without considering the spin magnetic found Spin polarization, device is a metal, and with the increasing size of the triangle of boron nitride, was gradually suppressed its ability to transport electrons. Considering spin polarization, the device into the semiconductor properties, and by changing the triangle of boron nitride size, can control the spin polarization properties. It is important in the in T_B_15N_21, the double magnetic semiconductor properties, and has very high filtration efficiency of the electron spin transport capacity and close to 100%, while R_3BNNR has the same rectangular boron nitride boron nitride atoms do not appear double magnetic semiconductor properties, and its electronic transport capacity is limited. Similar to graphene nano doped boron nitride triangle with triangle vacancy of V_B (15) N (21) also appeared double magnetic semiconductor properties, and also has a very high spin filter efficiency, but its electronic transport ability and stability As the doped boron nitride triangle T_B_ (15) N_ (21). (2) constructed parallel and vertical splicing of the MoS_2NRs and WS_2NR_s heterostructure. Study the electron transport properties of these heterostructures, found all heterostructures have shown the characteristics of direct band gap semiconductor, which means that the heterostructure can be used for optoelectronic devices. With the increase of WS_2NR_s nanobelts, weak band gap is smaller, leading to a rapid growth of current and higher peak current. In addition, with the increase of WS_2NR_s nanobelts, for M (NA) dual electrode device, negative differential resistance effect is greatly increased, and the M (NZ) negative change differential resistance effect of double electrode devices but showed the opposite trend, but the current growth faster, higher peak currents, which shows that the vertical mosaic M (NA) have better application prospect in logic circuit of double electrode device in particular, Tungsten atoms at the boundary of the M (edge) dual electrode device not only has negative differential resistance effect is significant, but also in the area of low pressure and high peak current, the logic circuit (3). The best application performance of the electronic armchair and zigzag type MoS_2NRs/WS_2NR_s heterostructures we found all transport properties. Armchair MoS_2NRs/WS_2NR_s heterostructures exhibit rectifying effect of current, means of this kind of structure can be applied to the PN node. With the increase of molecular rectifiers WS_2 heterostructure nanoribbons length, rectifying effect is suppressed, which is due to the positive pressure area of electronic transmission peaks decrease. In addition, in the area of positive pressure and the negative pressure region is observed in the negative differential resistance, and can be changed by WS_2 nano belt length to adjust the negative differential resistance strength. For all the zigzag MoS_2NRs/WS_2NR_s heterostructure, in addition to the negative micro Electrical effect, also observed the spin filtering effect, means that the heterogeneous structure can be used in spin electronic devices. With the increase of WS_2 heterostructure nanoribbons length, higher spin filtering efficiency, zMoS2-5zWS_2NR_s can reach 60%. when connecting WS_2 nanoband electrode, whether or not to consider the spin polarization, MoS_2NRs/WS_2NR_s heterostructures exhibit good electron transport properties, such as high spin filter efficiency and good effect. The negative differential resistance (4) carbon nano chain was studied, boron nitride nano electronic and nano chain chain, the heterogeneous structure of transport properties. We found all the single atomic chain have shown parity effect, and with the length of the increase transport properties were restrained. Even in single atomic chain, in addition to the pure carbon chain, there are current rectification effect, we found that the rectification effect is caused by the electronic structure of asymmetric lead The influence of tilt. In addition, the transport properties of carbon chain almost no, however the transmission ability of double carbon chain can be increased by two times. When considering spin polarization, all structures are magnetic semiconductors, and presents the parity of the spin filtering effect. It is essential that the chain channel determines the current density of states voltage characteristic curve of transmission spectrum and electronic devices. The change of current voltage curve, can explain the electronic transmission spectrum under equilibrium well, the Fermi level near and far from the Fermi level of the transmission peaks correspond well to the current low pressure area and high pressure area. In addition, the single atomic chain heterostructure, through the number of atoms change the carbon atoms and boron nitride, similar between rectifying effect can effectively regulate the electrical properties of.CnBNm heterojunction current to each other, showing rectification phenomenon of forward and reverse, and with the number of carbon atoms. Plus, the current transmission capacity doubled. Especially when the carbon atoms in the chain connecting channel and graphene nano, has greatly improved its ability to transport electrons, such as the current transmission capacity and rectifying effect. However, when considering spin polarization, spin filtering effect of carbon chain on the side of the better. The research content of this paper has important significance for understanding the electronic two-dimensional nano heterostructures and single atom nano chain transport properties, to provide theoretical guidance for the design and development of nano electronic devices with high performance.

【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB383.1
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本文編號(hào)：1385257