基于第一性原理的非晶硅建模仿真研究

发布时间：2018-06-18 09:23

本文选题：非晶硅 + 连续随机网格结构建模　；参考：《电子科技大学》2015年硕士论文

【摘要】：非晶硅在半导体材料中一直以来都扮演着重要的角色。人们投入了的大量工作研究纯非晶硅的性质。随后的研究工作集中在有更为稳定的材料结构的氢化非晶硅上。新的材料在带来创新的同时,同样也带来了新的挑战。非晶硅之于晶体硅最重要的优势就是其生产技术。通过PECVD等制造工艺,可以沉积出大面积的均匀氢化非晶硅膜。尽管以氢化非晶硅为基础的器件已得到广泛应用,但是对其物理性质仍然缺乏深入的研究。基于第一性原理建模计算更多的应用在规则晶体的研究中,对于非晶态连续随机网格结构的工作相对较少。本文基于第一性原理对非晶硅的建模方式进行研究分析。首先介绍了非晶硅薄膜的制备手段以及实验室的制备条件,并简单介绍了用于与模型的各项计算数据对比的实验数据的测试方法和仪器。以第一性原理为基础,利用“液相冷却”的方法建立包含64个硅原子和8个H原子的非晶硅结构模型。在建模的过程中引入了三种不同的冷却温度。随后通过比较结构因子、径向分布函数以及键角分布和另外的一些结构特点,探讨三种冷却速率对于模型的影响。得出慢速冷却的模型对于非晶硅的结构有着相对良好的还原。为了验证模型的大小对于仿真结果的影响,建立一个含有216个硅原子和24个氢原子的大型模型,并与小型模型印证,得出的建模方式是可以正确的反映非晶硅的结构特点。为了研究模型对于非晶硅光学性质的模拟,随后运用慢冷却速率建立了五个小型模型和一个大型模型,以及之前建立的快速/普通冷却速率的非晶硅模型,进行了光学性质的运算:吸收光谱、傅里叶红外谱、折射率和消光系数。从比较中得出,慢速冷却的模型无论是在结构特性还是光学特性上都接近于实验条件下的氢化非晶硅。
[Abstract]:Amorphous silicon has always played an important role in semiconductor materials. A lot of work has been done to study the properties of pure amorphous silicon. Subsequent studies focused on hydrogenated amorphous silicon with more stable material structures. New materials bring innovation as well as new challenges. The most important advantage of amorphous silicon to crystalline silicon is its production technology. A large area of homogeneous hydrogenated amorphous silicon films can be deposited by PECVD. Although hydrogenated amorphous silicon based devices have been widely used, their physical properties are still lack of in-depth study. First-principle modeling and calculation are more widely used in the study of regular crystals, and less work is done on amorphous continuous stochastic grid structures. Based on the first principle, the modeling method of amorphous silicon is studied and analyzed in this paper. Firstly, the preparation method of amorphous silicon thin film and the preparation conditions of the laboratory are introduced, and the measuring methods and instruments of the experimental data used to compare the calculated data with the model are briefly introduced. Based on the first principle, an amorphous silicon structure model containing 64 Si atoms and 8 H atoms was established by using the "liquid phase cooling" method. Three different cooling temperatures are introduced in the modeling process. Then, by comparing the structure factor, radial distribution function, bond angle distribution and some other structural characteristics, the influence of three cooling rates on the model is discussed. It is concluded that the model of slow cooling has relatively good reduction to the structure of amorphous silicon. In order to verify the influence of the size of the model on the simulation results, a large model containing 216 silicon atoms and 24 hydrogen atoms was established and verified with the small model. The model can correctly reflect the structural characteristics of amorphous silicon. In order to study the simulation of the optical properties of amorphous silicon, five small models and one large model were established by using slow cooling rate, and the fast / ordinary cooling rate model of amorphous silicon was established. Optical properties were calculated: absorption spectrum, Fourier infrared spectrum, refractive index and extinction coefficient. From the comparison, it is concluded that the model of slow cooling is close to the hydrogenated amorphous silicon under experimental conditions, both in structure and optical properties.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.12

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