本文選題：鍺烯　切入點：鍺量子點　出處：《浙江大學》2017年碩士論文

【摘要】：當前窄禁帶半導體材料中,晶體鍺由于具備良好的微電子兼容性而被寄予厚望。鍺材料比硅材料的波爾激子半徑更大,具有更加顯著的表面效應和量子限域效應等,因而鍺材料在半導體器件的應用上如集成電路、太陽電池、生物材料等更易獲得優(yōu)異的性能。近幾年,低維(二維、一維、零維)鍺材料的研究受到廣泛的關注,并取得了突破性的進展,如鍺烯(二維鍺材料)成功地在鉑、金襯底上合成,有力的促進了鍺烯在各個領域的應用。鍺烯結構與石墨烯相似,其帶隙約為0eV,所以鍺烯的器件化應用需要將其帶隙打開。研究者們已經(jīng)采用濕化學的方法合成了氫鈍化的鍺烯,其帶隙是3.6 eV,并且是直接帶隙,比硅烯(間接帶隙,4eV)具有更有大的研究前景。通過表面改性調控能帶,鍺烯比硅烯更有潛力成為一種重要的應用于光電子領域的半導體材料。現(xiàn)階段的相關研究還停留在對其尺寸效應對性能的影響,而摻雜研究非常少,并且極度缺乏理論的指導。因此通過密度泛函理論探索摻雜對鍺量子點的幾何結構和電子性能也亟待研究。本文研究了表面改性(氫化鍺烷化、烷氧基化、胺化及苯基化)對氫鈍化鍺烯電子結構的影響以及硼、磷摻雜對鍺量子點電子結構的調控作用和形成機制。主要取得以下結論:(1)氫化鍺烷化、烷氧基化、胺化及苯基化對氫鈍化鍺烯幾何結構的影響非常小。表面改性會增大氫鈍化鍺烯的禁帶寬度,尤其對烷基化和胺基化的鍺烯禁帶寬度影響較大。胺化和苯基化會使氫鈍化鍺烯由直接禁帶半導體變?yōu)殚g接禁帶半導體;而氫化鍺烷化和烷氧基化并不會改變其直接禁帶半導體的特征。(2)硼摻雜鍺量子點的形成能隨著硼在鍺量子點的中心位置向表面移動而逐漸降低,即硼原子最容易摻雜到鍺量子點的表面。當硼摻雜在鍺量子點內(nèi)部時,在價帶上方引入了深雜質能級,當硼摻雜到鍺量子點的表面時,在接近鍺量子點的禁帶中間的位置引入了深能級。磷摻雜鍺量子點的與硼的變化規(guī)律相似,但形成能比硼摻雜鍺量子點偏高,因此硼原子比磷原子更容易摻入到鍺量子點中。(3)對于硼磷共摻的鍺量子點,其形成能均小于硼原子和磷原子單摻的鍺量子點。而其電子結構中均在價帶上方引入了深能級。硼磷共摻使鍺量子點帶隙變化最大的為0.37 eV,接近硼磷共摻硅量子點帶隙變化的兩倍(0.2 eV),因此硼磷共摻的鍺量子點電子結構比硅量子點更具有可調控性。
[Abstract]:In current narrow band semiconductor materials, crystal germanium is expected to have good microelectronic compatibility. Germanium material has a larger Bolt exciton radius than silicon material, and has more obvious surface effect and quantum limiting effect, etc. Therefore, the application of germanium in semiconductor devices such as integrated circuits, solar cells, biomaterials, etc. In recent years, the research of low-dimensional (two-dimensional, one-dimensional, zero-dimensional) germanium materials has received extensive attention. Breakthrough progress has been made, such as the successful synthesis of germane (two-dimensional germanium) on platinum and gold substrates, which promotes the application of germane in various fields. The structure of germane is similar to that of graphene. The band gap of germanium is about 0 EV, so it is necessary to open the band gap for the device of germane. The researchers have synthesized hydrogen passivated germane by wet chemical method. The band gap is 3.6 EV and is a direct band gap. It is more promising than silyene (indirect band gap 4eV). Germane has more potential than silicene to become an important semiconductor material in the field of optoelectronics. Therefore, it is urgent to study the geometric structure and electronic properties of doped germanium quantum dots by density functional theory. In this paper, the surface modification (hydrogenation of germanium, alkoxylation of germanium, alkoxylation of germanium) is studied. The effects of amination and phenylation on the electronic structure of hydrogen passivated germanium and the effect of boron and phosphorus doping on the electronic structure of germanium quantum dots were studied. The main conclusions are as follows: 1) hydrogenated germanium alkylation, alkoxylation, The effect of amination and phenylation on the geometric structure of hydrogen passivated germanium is very small. The surface modification will increase the band gap of hydrogen passivated germanium. In particular, the band gap of alkylation and amination germane is greatly affected. Amination and phenylation can change the hydrogen passivated germanium from direct band gap semiconductor to indirect band gap semiconductor. However, the formation energy of boron doped germanium quantum dots decreases with the center position of boron moving toward the surface, but the alkylation and alkoxylation of germanium do not change the characteristics of the direct band gap semiconductor. The formation energy of boron doped germanium quantum dots decreases with the center position of germanium quantum dots moving to the surface. That is, boron atoms are most easily doped to the surface of germanium quantum dots. When boron is doped inside germanium quantum dots, deep impurity levels are introduced above the valence band, and when boron is doped into the surface of germanium quantum dots, Deep energy levels are introduced near the gap between the band gaps of the germanium quantum dots. The variation law of the phosphorus-doped germanium quantum dots is similar to that of boron, but the formation energy is higher than that of boron-doped germanium quantum dots. Therefore, boron atoms are more easily adulterated into germanium quantum dots than phosphorus atoms) for boron-phosphorus co-doped germanium quantum dots. The formation energy of GE quantum dots is smaller than that of boron atoms and phosphorus atoms, and deep energy levels are introduced above the valence band in the electronic structure. Boron and phosphorus co-doped germanium quantum dots with the largest band gap change is 0.37 EV, which is close to boron phosphorus co-doped silicon quantum. The change of band-gap is about 0.2 EV, so the electronic structure of boron-phosphorus co-doped germanium quantum dots is more controllable than that of silicon quantum dots.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1;O641.1

【參考文獻】

相關期刊論文 前1條

1 陳嵐;吳克輝;;硅烯:一種新型的二維狄拉克電子材料[J];物理;2013年09期

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本文編號：1668146