The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon
The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon
复制标题
电子比热对硅快重离子辐照模拟的影响
DOI：
10.1088/0953-8984/28/39/395201
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
D. Duffy
中科院分区：
文献类型：
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作者：
G. Khara;S. Murphy;S. Daraszewicz;D. Duffy
材料的快速重离子（SHI）辐照通常采用双温度模型。虽然该模型已经成功地描述了金属中的SHI损伤，但它无法解释半导体和绝缘体中存在的带隙。在这里，我们通过明确地将带隙的影响纳入Si的电子比热参数化来探索克服这一限制的潜力。利用有限温度密度泛函理论计算了比热作为电子温度的函数，具有三种不同的交换相关泛函，每种泛函都具有特征带隙。这些与电子温度相关的比热与双温分子动力学一起用于模拟硅中离子轨道的产生。使用密度泛函理论导出的比热得到的结果表明，与使用自由电子气体比热的模型相比，缺陷产生大大减少。因此，轨道半径更小，与实验观测结果更吻合。我们还观察到带隙宽度与径迹半径之间的相关性，这是由于电子比热对温度依赖性的变化引起的。
The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat.