硅单晶热膨胀性质的分子动力学与晶格动力学模拟
发布时间：2018-07-14 13:59
【摘要】：硅是地球上储藏最丰富、使用最广泛的半导体材料,在微电子领域已有大量应用。最近二十多年来,硅材料在微机电系统中也有广泛应用,如人们研制成功各种的硅微型压力传感器、硅微尺度的加速度计。热学性质是硅材料的一种基本物理性质,对它们的了解和掌握将有助于我们成功设计和可靠使用基于硅材料的各种微机电系统构件。热膨胀作为硅单晶材料的最重要的一种热学性质,长期以来得到了人们充分的理论与实验研究。人们通过实验,发现它在低温下有负热膨胀现象,研究表明,采用Stillinger-Weber模型,人们不能在低温下计算得到负热膨胀系数。因此应用该模型不能解释硅单晶材料的低温下有负热膨胀的物理机制,必须进行修正。本文将揭示硅晶体在低温下具有负热膨胀性质的微观机制,对Stillinger-Weber模型加以修正,使其能应用于硅单晶的热膨胀研究,为微型机电系统构件的合理设计和可靠使用提供理论依据。该研究方法同样适用于其他金刚石结构的晶体材料的热膨胀性质研究,具有普适性。本文的主要内容包括:1.介绍硅材料其热物性尤其是热膨胀性质的理论与实验研究现状及研究意义。2.介绍Stillinger-Weber模型下硅单晶分子动力学模拟的基本原理以及分子动力学模拟的主要步骤和流程,并加以实验数据进行模拟。3.采用晶格动力学的方法推导了硅单晶的热膨胀系数与原子间两体作用和三体作用的三阶力常数之间的关系式,通过微扰理论的运用推导出硅单晶的晶格常数和热膨胀系数的公式,由此探索硅单晶在低温下具有负热膨胀性质的物理机制。4.对硅单晶热膨胀性质的晶格动力学模拟结果、分子动力学模拟结果以及实验数据结果进行对比,并得出相关结论:硅单晶在低温下确实存在负热膨胀性质,引起该性质的根本原因是三阶力常数为正。
[Abstract]:Silicon is the most abundant and widely used semiconductor material on earth and has been widely used in the field of microelectronics. In recent twenty years, silicon materials have been widely used in MEMS, such as various silicon micro pressure sensors and silicon micro scale accelerometers. Thermal properties are one of the basic physical properties of silicon materials. Understanding and mastering them will help us to design and use various MEMS components based on silicon materials successfully. Thermal expansion, as one of the most important thermal properties of silicon single crystal, has been studied in theory and experiment for a long time. It is found that it has negative thermal expansion at low temperature through experiments. It is shown that the Stillinger-Weber model can not be used to calculate the negative thermal expansion coefficient at low temperature. Therefore, the model can not explain the physical mechanism of negative thermal expansion of silicon single crystal materials at low temperature, and must be modified. In this paper, the microcosmic mechanism of negative thermal expansion of silicon crystal at low temperature is revealed, and the Stillinger-Weber model is modified so that it can be applied to the study of thermal expansion of silicon single crystal, which provides a theoretical basis for the rational design and reliable use of micro electromechanical system components. This method is also suitable for the study of thermal expansion properties of other diamond crystal materials. The main contents of this paper include: 1. The present situation and significance of theoretical and experimental research on thermal physical properties, especially thermal expansion properties of silicon materials are introduced. The basic principle of molecular dynamics simulation of silicon single crystal under Stillinger-Weber model and the main steps and processes of molecular dynamics simulation are introduced. The relationship between the coefficient of thermal expansion of silicon single crystal and the third-order force constants of two-body interaction and three-body interaction between atoms is derived by the method of lattice dynamics. The formula of lattice constant and thermal expansion coefficient of silicon single crystal is derived by using perturbation theory, and the physical mechanism of negative thermal expansion property of silicon single crystal at low temperature is explored. The results of lattice dynamics simulation, molecular dynamics simulation and experimental data of the thermal expansion properties of silicon single crystals are compared, and some conclusions are drawn: the negative thermal expansion properties of silicon single crystals do exist at low temperature. The fundamental reason for this property is that the third order force constant is positive.
【学位授予单位】：湖南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.12
本文编号：2121871
[Abstract]:Silicon is the most abundant and widely used semiconductor material on earth and has been widely used in the field of microelectronics. In recent twenty years, silicon materials have been widely used in MEMS, such as various silicon micro pressure sensors and silicon micro scale accelerometers. Thermal properties are one of the basic physical properties of silicon materials. Understanding and mastering them will help us to design and use various MEMS components based on silicon materials successfully. Thermal expansion, as one of the most important thermal properties of silicon single crystal, has been studied in theory and experiment for a long time. It is found that it has negative thermal expansion at low temperature through experiments. It is shown that the Stillinger-Weber model can not be used to calculate the negative thermal expansion coefficient at low temperature. Therefore, the model can not explain the physical mechanism of negative thermal expansion of silicon single crystal materials at low temperature, and must be modified. In this paper, the microcosmic mechanism of negative thermal expansion of silicon crystal at low temperature is revealed, and the Stillinger-Weber model is modified so that it can be applied to the study of thermal expansion of silicon single crystal, which provides a theoretical basis for the rational design and reliable use of micro electromechanical system components. This method is also suitable for the study of thermal expansion properties of other diamond crystal materials. The main contents of this paper include: 1. The present situation and significance of theoretical and experimental research on thermal physical properties, especially thermal expansion properties of silicon materials are introduced. The basic principle of molecular dynamics simulation of silicon single crystal under Stillinger-Weber model and the main steps and processes of molecular dynamics simulation are introduced. The relationship between the coefficient of thermal expansion of silicon single crystal and the third-order force constants of two-body interaction and three-body interaction between atoms is derived by the method of lattice dynamics. The formula of lattice constant and thermal expansion coefficient of silicon single crystal is derived by using perturbation theory, and the physical mechanism of negative thermal expansion property of silicon single crystal at low temperature is explored. The results of lattice dynamics simulation, molecular dynamics simulation and experimental data of the thermal expansion properties of silicon single crystals are compared, and some conclusions are drawn: the negative thermal expansion properties of silicon single crystals do exist at low temperature. The fundamental reason for this property is that the third order force constant is positive.
【学位授予单位】：湖南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.12
【参考文献】
相关期刊论文 前1条
1 黄建平;胡诗一;;由热学性质获取氩晶体原子间各阶力常数[J];原子与分子物理学报;2014年06期
，本文编号：2121871
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