Abstract

Silicon is indispensable in semiconductor industry. Understanding its high-temperature thermodynamic properties is essential both for theory and applications. However, first-principle description of high-temperature thermodynamic properties of silicon (thermal expansion coefficient and specific heat) is still incomplete. Strong deviation of its specific heat at high temperatures from the Dulong–Petit law suggests substantial contribution of anharmonicity effects. We demonstrate, that anharmonicity is mostly due to two transverse phonon modes, propagating in (111) and (100) directions, and can be quantitatively described with formation of the certain type of nanostructured planar defects of the crystal structure. Calculation of these defects' formation energy enabled us to determine their input into the specific heat and thermal expansion coefficient. This contribution turns out to be significantly greater than the one calculated in quasi-harmonic approximation.

中文翻译：

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平面缺陷是解释硅高温热力学性质显式非谐性的一种方法

摘要

硅在半导体工业中是不可或缺的。了解其高温热力学性质对于理论和应用都至关重要。然而，硅的高温热力学性质（热膨胀系数和比热）的第一性原理描述仍然不完整。其高温比热与杜隆-珀蒂定律的强烈偏差表明非谐效应的重大贡献。我们证明，非谐性主要是由于两个横向声子模式在（111）和（100）方向传播，并且可以通过晶体结构的某种类型的纳米结构平面缺陷的形成来定量描述。对这些缺陷形成能的计算使我们能够确定它们对比热和热膨胀系数的输入。事实证明，这一贡献明显大于准调和近似计算的贡献。