本文關(guān)鍵詞： 第一性原理 二維納米材料 自旋極化 量子自旋霍爾效應(yīng) 半導(dǎo)體性質(zhì)　出處：《山東大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：二維納米材料由于原材料豐富以及性質(zhì)優(yōu)良等突出特點,是當(dāng)今科學(xué)研究領(lǐng)域的熱點。尤其是在石墨烯成功制備后,人們發(fā)現(xiàn)這種二維單層材料具有良好的機械性能和物理化學(xué)性質(zhì)。石墨烯的成功問世,進(jìn)一步激發(fā)了人們探索新型二維納米材料的研究熱情。目前,已有諸多二維納米材料被成功預(yù)測甚至合成,它們優(yōu)異的性能在不同領(lǐng)域都表現(xiàn)出重要的應(yīng)用價值。如,在自旋電子學(xué)應(yīng)用方面,二維磁性納米材料體系具有較穩(wěn)定的自旋極化性質(zhì)和優(yōu)良的結(jié)構(gòu)-性能穩(wěn)定性,能夠滿足當(dāng)今時代越來越高的存儲和處理能力與越來越小的器件尺寸的雙重需求,可以作為新一代高性能自旋納米器件;在新奇物理效應(yīng)方面,二維拓?fù)浣^緣體材料體系具有奇異的量子自旋霍爾效應(yīng),即邊緣態(tài)受到拓?fù)浔Ｗo(hù),并且自旋在邊緣態(tài)中可以無耗散的高速遷移,在進(jìn)一步提高新一代自旋電子設(shè)備性能、降低能耗等方面表現(xiàn)出重要的應(yīng)用潛力;在半導(dǎo)體應(yīng)用方面,二維半導(dǎo)體納米材料體系通常具有超高的比表面積、外場可控的能帶結(jié)構(gòu)、較高的載流子遷移率和合適的半導(dǎo)體帶邊位置,為我們尋找新型高效的納米半導(dǎo)體材料,實現(xiàn)電子器件和光催化等方面的應(yīng)用提供了新途徑。在本論文中,我們借助第一性原理計算系統(tǒng)地研究了一系列新型二維納米材料體系的電子結(jié)構(gòu)和相關(guān)性質(zhì),并對其微觀物理機制進(jìn)行了深入探討,研究了二維納米材料在自旋電子學(xué)、量子自旋霍爾效應(yīng)和半導(dǎo)體電子結(jié)構(gòu)及調(diào)控等多方面的性質(zhì),為二維納米材料在節(jié)約能源、降低能耗和能源轉(zhuǎn)換等多方面的應(yīng)用提供了系統(tǒng)的理論指導(dǎo)。本文第一章介紹二維納米材料的發(fā)展現(xiàn)狀與應(yīng)用以及本論文主要研究內(nèi)容。第二章介紹第一性原理計算的理論基礎(chǔ)和軟件包。第三章研究基于過渡金屬的二維磁性納米材料體系的電子結(jié)構(gòu)和自旋極化性質(zhì),并探討了體系自旋極化性質(zhì)的調(diào)控。第四章詳細(xì)地展示了二維納米材料體系中的量子自旋霍爾效應(yīng),設(shè)計了一系列室溫二維拓?fù)浣^緣體體系。第五章詳細(xì)研究了二維納米材料和其復(fù)合體系的半導(dǎo)體電子結(jié)構(gòu)調(diào)控以及在電子器件、光解水等方面的潛在應(yīng)用。第六章對本論文的主要結(jié)論和創(chuàng)新點進(jìn)行了總結(jié),并對新型二維納米材料的理論研究做了展望。本論文的主要研究內(nèi)容和結(jié)果如下:(1)研究了二維 TM(TM = Ti、Zr、Hf、V、Nb 和 Ta)單層材料以及 TM(TM= Ti、V、Cr、Mn和Fe)與鍺環(huán)構(gòu)成的納米分子鏈[(Ge5)TM]∞的電子結(jié)構(gòu)和自旋極化性質(zhì)。研究表明Ti、Zr、Hf單層以及[(Ge5)TM]∞(TM=Ti和Fe)具有鐵磁基態(tài),其鐵磁性來源于TM原子的d電子。此外,TM單層的居里溫度大于580 K,在室溫下也能保持較高的自旋極化率。這些結(jié)果為新型自旋電子器件的發(fā)展開辟了道路。(2)探索了一系列二維納米材料體系中的量子自旋霍爾效應(yīng),其中包括g-TlA(A = N、P、As和Sb)和TMC6(TM = Mo和W)體系。結(jié)果表明這些體系中較強的自旋軌道耦合作用(SOC)能夠在費米能級附近引入能帶反轉(zhuǎn),同時產(chǎn)生拓?fù)浔Ｗo(hù)的邊緣態(tài)。且這些二維體系的帶隙寬度均大于室溫下電子的躍遷能(26 meV),是室溫下理想的二維拓?fù)浣^緣體材料。(3)研究了二維復(fù)合拓?fù)浣^緣體體系GeI/MoTe2的電子結(jié)構(gòu)和拓?fù)湫再|(zhì)。并且證實MoTe2都是二維拓?fù)浣^緣體GeI單層的理想襯底。以MoTe2為襯底的GeI單層,其帶隙寬度是240 meV,比室溫下電子躍遷能(26 meV)大了將近一個數(shù)量級。同時,SOC作用下費米能級附近非平庸的能帶反轉(zhuǎn)機制可以通過直接計算體系的自旋陳數(shù)Cs= 1得到證實。我們解決了目前二維拓?fù)浣^緣體和襯底相互作用過強使得邊緣態(tài)與襯底能帶相耦合,導(dǎo)致實驗中不能觀測到拓?fù)鋺B(tài)的關(guān)鍵科學(xué)問題。(4)探索了二維復(fù)合半導(dǎo)體材料體系graphene/g-C3N4和MoS2/MXene(MXene = Ti2C02、Zr2C02和Hf2C02)的電子結(jié)構(gòu)和能帶調(diào)控。研究結(jié)果表明層間弱范德瓦爾斯相互作用能夠使得體系的電荷重新分布,導(dǎo)致復(fù)合體系的能帶結(jié)構(gòu)兼?zhèn)鋬煞N不同單層的性質(zhì)。Graphene/g-C3N4復(fù)合體系是帶隙寬度為106meV的半導(dǎo)體,而其費米能級附近仍能夠保持類似石墨烯體系中的較小的有效質(zhì)量和較大的費米速度。MoS2/MXene體系形成了 Type-II半導(dǎo)體能帶對齊方式,使得電子和空穴分別分布在MXene和MoS2上,實現(xiàn)了載流子的空間分離。另外,研究還發(fā)現(xiàn)這些二維復(fù)合納米材料體系的能帶結(jié)構(gòu)均可以通過外場(電場、應(yīng)力等)進(jìn)行有規(guī)律地調(diào)控。(5)研究了一系列新型非金屬硅基二維材料p-SiX(X = B、C和N)以及無機非金屬螺旋納米鏈體系XYP(X = Si、Ge和Sn;Y = Cl、Br和I)。結(jié)果表明p-SiC和無機非金屬螺旋納米鏈體系XYP是帶隙寬度在2.21～2.96 eV之間的半導(dǎo)體體系,其帶隙寬度恰好對應(yīng)太陽光譜的可見光波段。進(jìn)一步研究表明這些材料具有較高的載流子遷移率,并且其帶隙寬度與帶邊位置均能滿足光解水的氧化還原電勢。這一研究為實驗制備新型高效的光催化劑提供了重要的理論基礎(chǔ)。
[Abstract]:Two dimensional nano materials due to abundant raw materials and other excellent properties of outstanding features, is a hot spot in the field of scientific research. Especially in graphene was successfully prepared, people found that the two-dimensional single-layer material has excellent physical and chemical properties and mechanical properties. Graphene successfully come out, to further stimulate the enthusiasm of the people to explore a new two-dimensional nano materials. At present, there are many two-dimensional nano materials are successfully predicted even their synthesis, excellent performance in different areas are showing important application value. For example, in spintronics applications, two dimensional magnetic nanomaterials spin polarization system has stable properties and excellent structure stability, can meet the dual requirements of storage and the ability to deal with more and more nowadays more and more small size of the device, can be used as a new generation of high performance spin nano meter In the novel; physical effect, 2D topological insulator material system with spin quantum Holzer effect of singularity, namely edge state by topology protection, and high-speed non dissipative spin migration at the edge of state, to further enhance the performance of a new generation of spin electronic devices, reduce the energy consumption and show great potential applications in; the application of two-dimensional semiconductor, semiconductor nano material system usually has a high specific surface area, the band structure of field controlled, high carrier mobility and appropriate semiconductor band edge position, looking for new and efficient nano semiconductor materials for us, provides a new way to realize the application of electronic devices and catalysis fields. In in this paper, we use the first principle calculation system to study the electronic structure of a series of novel two-dimensional nano material system and related properties, and the micro The concept of physical mechanism in-depth discussion, study the two-dimensional nano materials in spintronics, the spin properties of quantum Holzer effect and semiconductor electronic structure and control and other aspects of the two-dimensional nano materials in energy conservation, provides a theoretical guidance for system application in many aspects of reducing energy consumption and energy conversion. The first chapter is the introduction of two dimensional nano material development and application as well as the main content of this thesis. The second chapter introduces the first principle calculation theory and software package. The third chapter studies on the electronic structure and spin polarization properties of two-dimensional magnetic nano materials, transition metal, and discusses the regulation of spin polarization properties of the system. The fourth chapter shows quantum spin Holzer effect of two-dimensional nano materials in the system, the design of a series of room temperature 2D topological insulator system. The fifth chapter studies two 緇寸撼綾蟲潗鏂欏拰鍏跺鍚堜綋緋葷殑鍗婂浣撶數(shù)瀛愮粨鏋勮皟鎺т互鍙婂湪鐢?shù)瀛愬櫒錃g,鍏夎В姘寸瓑鏂歸潰鐨勬綔鍦ㄥ簲鐢，

本文編號：1459951