動力學蒙特卡羅法模擬Si（100）基Ge納米島的生長
發(fā)布時間：2018-08-11 16:53
【摘要】：半導體量子點在納米電子學、納米光子學和光電子學等領域具有相當廣泛的應用前景,基于量子點的固態(tài)量子器件在量子信息技術中將扮演重要角色。Ge/Si量子點由于具有與大規(guī)模集成電路相兼容的特點,成為研究的熱點之一。為深入理解生長因素及應變對量子點形成的影響,動力學蒙特卡羅方法(KMC)被廣泛應用于量子點生長的研究,并已取得了與實際情況相符的結果。 論文采用動力學蒙特卡羅法結合MATLAB編程,模擬了Si(100)基底上生長Ge量子點的初期二維Ge納米島成核過程。二維Ge納米島是量子點生長的核心,它的狀態(tài)決定著三維島狀結構量子點的成核位置、尺寸和形貌等結構特性,而二維Ge納米島在實驗上是難于觀察的,因此對二維Ge納米島的模擬研究有著重要意義。論文采用200×200的四方形格子,作為Ge量子點生長的Si(100)基底,模擬過程主要考慮原子的沉積與擴散兩個過程,而不考慮吸附原子的脫附過程。Ge原子在襯底擴散采用周期性邊界條件。 首先系統(tǒng)研究了基本生長參數(shù)對二維Ge納米島的成核位置、尺寸大小和均勻性、密度以及分布有序性等方面的影響。隨著生長溫度的增加,原子擴散能力增強,二維Ge納米島的尺寸增大,密度減�。欢SGe納米島在的退火過程中的穩(wěn)定性,隨著退火時間增加,吸附原子的平均擴散幾率增加,它們會擴散到勢能更低的地方聚集,二維Ge納米島尺寸增大,密度減小,觀察到Ostwald Ripening過程；隨著原子沉積量的增大,二維Ge納米島密度先增加后減少,尺寸不斷增加,量子點間的距離不斷減少,甚至出現(xiàn)島的連結現(xiàn)象。 其次研究了圖形襯底上二維Ge納米島隨生長溫度和原子沉積的變化。溫度較低時,沉積原子受圖形襯底的影響不大,隨著溫度增加,原子不斷在圖形襯底中形核成為二維島,但是在過高的溫度下,沉積原子的擴散能力強,會脫離圖形襯底的束縛,不利于形成分布有序的量子點陣列；同樣原子沉積量過小或過大都不利于有序量子點陣列的制備,過小使得量子點尺寸不均勻,過大會破壞有序性。 最后研究了生長停頓和沉積原子能量對圖形襯底上量子點生長初期的表面形態(tài)、島尺寸分布及空間分布等方面的影響。研究發(fā)現(xiàn),在所選取的停頓時間范圍內,時間越長,二維Ge納米島的有序性和均勻性越好：停頓次數(shù)的增加,會提高原子的擴散能力,因此停頓次數(shù)適中時可以獲得有序均勻的二維Ge納米島陣列,最佳停頓次數(shù)為3次；沉積原子的剩余能量的增加,可使圖形襯底上二維Ge納米島的分布更加有序,尺寸也更均一,這是沉積原子得到適當擴散的結果。 通過對Si基底上二維Ge納米島的生長模擬,分析了量子點生長的物理機制,得到了生長優(yōu)質Ge量子點的工藝參數(shù)。為獲得空間有序的量子點陣、調整和優(yōu)化制備工藝提供了重要的理論依據(jù)。
[Abstract]:Semiconductor quantum dots have a wide range of applications in the fields of nano-electronics, nano-photonics and optoelectronics. Solid state quantum devices based on quantum dots will play an important role in quantum information technology. Ge- / Si quantum dots have become one of the hotspots for their compatibility with large scale integrated circuits (LSI). In order to understand the effect of growth factors and strain on the formation of quantum dots, the kinetic Monte Carlo method (KMC) has been widely used in the study of quantum dot growth. The nucleation process of GE quantum dots grown on Si (100) substrate was simulated by dynamic Monte Carlo method and MATLAB programming. Two-dimensional GE nanoscale island is the core of quantum dot growth. Its state determines the nucleation location, size and morphology of three-dimensional island structure quantum dot, while two-dimensional GE nanoscale island is difficult to observe experimentally. Therefore, it is of great significance to simulate the two-dimensional GE nanoscale island. In this paper, a square lattice of 200 脳 200 is used as the Si (100) substrate grown by GE quantum dots. The simulation process mainly considers the deposition and diffusion of atoms, but not the desorption process of adsorbed atoms. The periodic boundary conditions are adopted for the diffusion of GE atoms on the substrate. The effects of basic growth parameters on the nucleation location, size, uniformity, density and distribution order of two-dimensional GE nanoliths were studied systematically. With the increase of growth temperature, the diffusion ability of atoms increases, the size of two-dimensional GE nanoislands increases and the density decreases, and the stability of two-dimensional GE nanowires during annealing process increases with the increase of annealing time, and the average diffusion probability of adsorbed atoms increases with the increase of annealing time. The density of two-dimensional GE nanowires increases and decreases, and the Ostwald Ripening process is observed. With the increase of atomic deposition amount, the density of two-dimensional GE nanowires increases first and then decreases, and the size increases continuously. The distance between quantum dots is decreasing, and even the island is connected. Secondly, the change of two-dimensional GE nanoisland with growth temperature and atomic deposition on the graphic substrate is studied. When the temperature is low, the deposited atoms are not affected by the graphic substrate. With the increase of temperature, the atoms nucleate into two-dimensional islands in the graphic substrate, but the diffusion ability of the deposited atoms is strong at too high temperature. It is not conducive to the formation of an ordered quantum dot array, but the small or too large amount of atomic deposition is not conducive to the preparation of the ordered quantum dot array, so that the quantum dot size is not uniform and the order is destroyed by the excessive assembly. Finally, the effects of growth standstill and deposited atomic energy on the surface morphology, island size distribution and spatial distribution of QDs on graphical substrates are studied. The study found that the longer the pause time is, the better the order and uniformity of the two-dimensional GE nanoscale island is: the increase in the number of pauses increases the diffusion ability of atoms. Therefore, when the number of pauses is moderate, an ordered and uniform two-dimensional GE nanoisland array can be obtained, and the optimal number of pauses is 3 times, and the increase of residual energy of the deposited atoms can make the distribution of two-dimensional GE nanowires on the graphic substrate more orderly. The size is also more uniform, which is due to the proper diffusion of the deposited atoms. By simulating the growth of two-dimensional GE nanowires on Si substrate, the physical mechanism of quantum dot growth is analyzed, and the technological parameters for the growth of high quality GE quantum dots are obtained. It provides an important theoretical basis for obtaining ordered quantum lattice, adjusting and optimizing the preparation process.
【學位授予單位】：云南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB383.1;O614.431
本文編號：2177631
[Abstract]:Semiconductor quantum dots have a wide range of applications in the fields of nano-electronics, nano-photonics and optoelectronics. Solid state quantum devices based on quantum dots will play an important role in quantum information technology. Ge- / Si quantum dots have become one of the hotspots for their compatibility with large scale integrated circuits (LSI). In order to understand the effect of growth factors and strain on the formation of quantum dots, the kinetic Monte Carlo method (KMC) has been widely used in the study of quantum dot growth. The nucleation process of GE quantum dots grown on Si (100) substrate was simulated by dynamic Monte Carlo method and MATLAB programming. Two-dimensional GE nanoscale island is the core of quantum dot growth. Its state determines the nucleation location, size and morphology of three-dimensional island structure quantum dot, while two-dimensional GE nanoscale island is difficult to observe experimentally. Therefore, it is of great significance to simulate the two-dimensional GE nanoscale island. In this paper, a square lattice of 200 脳 200 is used as the Si (100) substrate grown by GE quantum dots. The simulation process mainly considers the deposition and diffusion of atoms, but not the desorption process of adsorbed atoms. The periodic boundary conditions are adopted for the diffusion of GE atoms on the substrate. The effects of basic growth parameters on the nucleation location, size, uniformity, density and distribution order of two-dimensional GE nanoliths were studied systematically. With the increase of growth temperature, the diffusion ability of atoms increases, the size of two-dimensional GE nanoislands increases and the density decreases, and the stability of two-dimensional GE nanowires during annealing process increases with the increase of annealing time, and the average diffusion probability of adsorbed atoms increases with the increase of annealing time. The density of two-dimensional GE nanowires increases and decreases, and the Ostwald Ripening process is observed. With the increase of atomic deposition amount, the density of two-dimensional GE nanowires increases first and then decreases, and the size increases continuously. The distance between quantum dots is decreasing, and even the island is connected. Secondly, the change of two-dimensional GE nanoisland with growth temperature and atomic deposition on the graphic substrate is studied. When the temperature is low, the deposited atoms are not affected by the graphic substrate. With the increase of temperature, the atoms nucleate into two-dimensional islands in the graphic substrate, but the diffusion ability of the deposited atoms is strong at too high temperature. It is not conducive to the formation of an ordered quantum dot array, but the small or too large amount of atomic deposition is not conducive to the preparation of the ordered quantum dot array, so that the quantum dot size is not uniform and the order is destroyed by the excessive assembly. Finally, the effects of growth standstill and deposited atomic energy on the surface morphology, island size distribution and spatial distribution of QDs on graphical substrates are studied. The study found that the longer the pause time is, the better the order and uniformity of the two-dimensional GE nanoscale island is: the increase in the number of pauses increases the diffusion ability of atoms. Therefore, when the number of pauses is moderate, an ordered and uniform two-dimensional GE nanoisland array can be obtained, and the optimal number of pauses is 3 times, and the increase of residual energy of the deposited atoms can make the distribution of two-dimensional GE nanowires on the graphic substrate more orderly. The size is also more uniform, which is due to the proper diffusion of the deposited atoms. By simulating the growth of two-dimensional GE nanowires on Si substrate, the physical mechanism of quantum dot growth is analyzed, and the technological parameters for the growth of high quality GE quantum dots are obtained. It provides an important theoretical basis for obtaining ordered quantum lattice, adjusting and optimizing the preparation process.
【學位授予單位】：云南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB383.1;O614.431
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