本文關(guān)鍵詞：硅基原子層厚結(jié)構(gòu)的計(jì)算研究　出處：《浙江大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 硅烯 空位 氧化 黑磷量子點(diǎn)/硅烯雜化 超晶格 密度泛函理論 能帶隙

【摘要】：石墨烯、硅烯和鍺烯等二維材料的發(fā)現(xiàn)引起了人們極大的研究興趣,這主要是由于其優(yōu)異的物理性質(zhì)和廣泛應(yīng)用前景。其中,具有蜂窩狀晶格結(jié)構(gòu)的由單層硅原子構(gòu)成的硅烯因其特殊的性質(zhì)而成為近年來研究的熱點(diǎn)。理論表明具有l(wèi)ow-buckled結(jié)構(gòu)的硅烯在電場(chǎng)調(diào)控電子結(jié)構(gòu)和與傳統(tǒng)的硅基工藝兼容等方面比平面結(jié)構(gòu)的石墨烯更有優(yōu)勢(shì)。然而,本征硅烯的零帶隙是阻礙其在器件領(lǐng)域應(yīng)用的主要障礙。本論文在密度泛函理論(DFT)的框架下,研究了氧化、空位、納米化和雜化結(jié)構(gòu)對(duì)硅烯結(jié)構(gòu)、電子和磁學(xué)性質(zhì)的影響,為硅烯的電子結(jié)構(gòu)和性能調(diào)控提供理論支持。本論文取得的主要成果如下:(1)研究了銀(111)面上氧化的硅烯的形成能、結(jié)構(gòu)和電子性質(zhì),考察氧化對(duì)銀(111)面上硅烯性能的影響。結(jié)果表明,氧化會(huì)改變銀(111)面上硅烯的蜂窩狀晶格結(jié)構(gòu)。由于氧化硅烯和銀(111)面強(qiáng)烈的耦合作用使氧化硅烯具有金屬特性的能帶結(jié)構(gòu)。氧化硅烯和銀(111)表面之間的電荷積累表明兩者形成了化學(xué)鍵和,這會(huì)顯著影響氧化硅烯的的電子性質(zhì)。當(dāng)氧化硅烯從銀(111)面上剝離時(shí),它們有可能變成半導(dǎo)體。(2)系統(tǒng)研究了具有不同空位濃度硅烯的形成能、電子和磁學(xué)性質(zhì),并和石墨烯進(jìn)行對(duì)比。研究發(fā)現(xiàn),硅烯的磁矩隨著其中空位濃度的增加而減小。此外,和具有空位的石墨烯相比,具有空位的low-buckled硅烯可能具有更加顯著的帶隙。隨著空位的形成,硅烯會(huì)從半金屬轉(zhuǎn)變?yōu)榘雽?dǎo)體,而石墨烯會(huì)變成金屬。(3)研究了不同尺寸氫鈍化的黑磷量子點(diǎn)(BPQDs)和黑磷量子點(diǎn)/硅烯雜化結(jié)構(gòu)的電子性質(zhì),結(jié)果表明黑磷量子點(diǎn)最高占據(jù)分子軌道(HOMO)和最低未占據(jù)分子軌道(LUMO)之間的帶隙隨著量子點(diǎn)尺寸的減小而增大,量子點(diǎn)穩(wěn)定性卻隨著尺寸減小而減弱。黑磷量子點(diǎn)/硅烯雜化結(jié)構(gòu)的吸附能和帶隙隨著量子點(diǎn)尺寸的增加而增大。硅烯上吸附P76H22量子點(diǎn)會(huì)使硅烯具有102 meV的禁帶寬度。電荷轉(zhuǎn)移分析表明電荷從硅烯轉(zhuǎn)移到黑磷量子點(diǎn),并且轉(zhuǎn)移的電荷量與硅烯表面黑磷量子點(diǎn)的覆蓋率有關(guān)。(4)研究了 Si6-xCx/C超晶格的電子性質(zhì)。通過替換石墨烯中的碳原子構(gòu)建不同硅碳比例的Si6-xCx/C超晶格。結(jié)果表明,Si6-xCx/C超晶格在狄拉克(Dirac)處具有直接帶隙,其電荷的有效質(zhì)量為0.016-0.646me。Si6-xCx/C超晶格的帶隙強(qiáng)烈地依賴于六元環(huán)石墨烯中硅原子的數(shù)量和位置。通過PBE交換關(guān)聯(lián)泛函和B3LYP雜化泛函計(jì)算得到Si3C3/C超晶格具有最大的帶隙,分別為0.3和0.54 eV。對(duì)其進(jìn)一步的研究表明,Si3C3/C超晶格在室溫下的載流子遷移率高達(dá)1.2854x105cm2V-1s-,其聲子熱導(dǎo)率為15.48Wm-1K-1。結(jié)合傳輸系數(shù)和低聲子熱導(dǎo)率,通過微調(diào)Si3C3/C超晶格中的載流子濃度,可以優(yōu)化其熱點(diǎn)品質(zhì)因數(shù)到1.95。
[Abstract]:The discovery of two-dimensional materials such as graphene, Silene and germanene has attracted great interest, mainly due to their excellent physical properties and wide application prospects. Among them, the Silene, which is composed of monolayer silicon atoms with honeycomb lattice structure, has become a hot spot in recent years because of its special properties. The theory shows that Silene with low-buckled structure has advantages over planar structure graphene in terms of electric field regulation, electronic structure and compatibility with traditional silicon-based process. However, the zero band gap of the intrinsic silicon is the main obstacle that hinders its application in the field of devices. In the framework of density functional theory (DFT), we have studied the effects of oxidation, vacancy, Nanocrystallization and hybrid structure on the structure, electronic and magnetic properties of silylene, providing theoretical support for the electronic structure and property control of silylene. The main achievements of this paper are as follows: (1) the formation energy, structure and electronic properties of silylene on silver (111) surface were investigated, and the effect of oxidation on the properties of silylene on silver (111) surface was investigated. The results show that oxidation will change the honeycomb lattice structure of Silene on the silver (111) surface. Because of the strong coupling effect of Silene and silver (111) surface, the SiO2 has a metal band structure. The charge accumulation between the silicon oxide and the silver (111) surface indicates that both of them form chemical bonds, which will significantly affect the electronic properties of the SiO2. When the silicon oxide is stripped from the silver (111) surface, they may become semiconductors. (2) the formation energy, electron and magnetic properties of Silene with different vacancy concentration are systematically studied and compared with Shi Moxi. It is found that the magnetic moment of Silene decreases with the increase of the vacancy concentration. In addition, the low-buckled Silene with vacant positions may have a more significant band gap compared with the vacant graphene. With the formation of vacancies, Silene will change from semi metal to semiconductors, and graphene will become metal. (3) black phosphorus quantum dots of different sizes of hydrogen passivation (BPQDs) and electronic properties of black phosphorus / silicon quantum dot graphene hybrid structure. The results show that black phosphorus quantum dots of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap between the increases with the size of quantum dots the decrease of quantum dots were decreased with decreasing the size and stability. The adsorption energy and band gap of the black phosphorus quantum dot / Silene hybrid structure increase with the increase of the quantum dot size. The adsorption of P76H22 quantum dots on Silene makes Silene with a band gap of 102 meV. Charge transfer analysis shows that the charge transfer from Silene to black phosphorus quantum dots, and the amount of transfer charge is related to the coverage of the black phosphorus quantum dots on the Silene surface. (4) the electronic properties of Si6-xCx/C superlattice are studied. Si6-xCx/C superlattices with different ratios of silicon and carbon are constructed by replacing carbon atoms in graphene. The results show that the Si6-xCx/C superlattice has a direct band gap at Dirac (Dirac), and the effective mass of the charge is 0.016-0.646me. The band gap of the Si6-xCx/C superlattice strongly depends on the number and position of the silicon atom in the six membered ring graphene. The maximum band gaps of Si3C3/C superlattices are obtained by the PBE exchange functional and B3LYP hybrid functional calculations, which are 0.3 and 0.54 eV, respectively. The further study shows that the carrier mobility of Si3C3/C superlattice at room temperature is up to 1.2854x105cm2V-1s-, and its phonon thermal conductivity is 15.48Wm-1K-1. Combining the transmission coefficient and the low sound conductivity, the hot quality factor of the Si3C3/C superlattice can be optimized by fine tuning the carrier concentration in the superlattice, and the quality factor of the hot spot can be optimized to 1.95.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O613.72

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 王蓉;徐明生;皮孝東;;Chemical modification of silicene[J];Chinese Physics B;2015年08期

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本文編號(hào)：1341151