掺杂半导体β-FeSi2电子结构及几何结构第一性原理研究

采用基于第一性原理的密度泛函理论全势线性缀加平面波法，使用广义梯度近似处理交换相关势能，首先计算了β-FeSi₂的电子结构及其各元素各亚层电子的能态密度，β-FeSi₂的电子能态密度主要由Fe的d层电子和Si的p层电子的能态密度确定；其次通过计算不同掺杂系统的总能量确定了掺杂原子在β-FeSi₂中的置换位置，在β-FeSi₂中，Co置换Fe_Ⅱ位置的Fe原子，Al置换Si_Ⅰ位置的Si原子，这种择位置换与现有的计算结果完全一致；最后计算了Fe_1-xCo_xSi₂和Fe(Si_1-xAl_x)₂的电子结构，对它们的电子结构特征进行了分析，并探讨了电子结构对其热电性能(塞贝克系数、电传输及热传输性能)的影响. 关键词： 第一性原理 电子结构 热电性能 2')" href="#">FeSi₂

A first-principle study of electronic and geometrical structures of semiconducting β-FeSi2 with doping

Firstly,the electronic structure of β-FeSi₂ and the density of states (DOS) of subshells of Fe and Si were calculated. The calculations were carried out using the self-consistent full-potential linearized augmented plane wave method within the density functional theory. The general gradient approximation was used to treat the exchange and correlation potential. The DOS of β-FeSi₂ is mainly composed of d-shell electrons of Fe and p-shell electrons of Si. Secondly,the stable atomic substitution positions of doping atoms were determined by calculating the total energies for Fe_1-xCo_xSi₂ and Fe(Si_1-xAl_x)₂. The Fe atom at the Fe_Ⅱ position and the Si atom at the Si_Ⅰ position were preferentially substituted by Co and Al,respectively. This preferential substitution is in good agreement with results of the existing publications. Finally,the elctronic structures of Fe_1-xCo_xSi₂ and Fe(Si_1-xAl_x)₂ were calculated and analyzed as well. The intrinsic relations between electronic structures of Fe_1-xCo_xSi₂ and Fe(Si_1-xAl_x)₂ and their respective thermoelectric properties including Seebeck coefficient,electric conductivity and thermal conductivity were discussed in detail.