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Al掺杂对Mg2Si介电性质影响的第一性原理研究
First Principles Study on Dielectric Properties of Al-doped Mg2Si
摘要点击 77  全文点击 20  投稿时间:2017-09-07  修订日期:2017-10-16
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DOI编号  
中文关键词   Al掺杂Mg2Si,第一性原理,形成能,电子结构,介电性质
英文关键词   Al-doped Mg 2 Si  First-principle  Formation energy  Electronic structure  Dielectric properties
基金项目   安顺学院航空电子电气与信息网络贵州省高校工程技术研究中心开放基金资助项目( HKDZ201403);国家自然科学基金资助项目( 61264004) ; 贵州省自然科学基金资助项目( [2014]2052,[2013]2209) ;贵州省科技厅贵州大学联合基金资助项目(20147610) ; 贵州省普通高等学校低维凝聚态物理重点实验室(批准号:黔教合KY字[2016]002);贵州省科技厅贵州师范大学联合基金项目(黔科合J字LKS[2013]12号)
作者单位E-mail
廖杨芳 贵州师范大学 723530283@qq.com 
肖清泉 贵州大学 qqxiaohn@126.com 
谢泉 贵州大学 1144582393@qq.com 
王善兰 贵州电子信息职业技术学院 124060649@qq.com 
周瑞雪 贵州师范大学 353040318@qq.com 
中文摘要
    采用基于密度泛函理论的第一性原理平面波超软赝势方法,计算了本征Mg 2 Si 和Al掺杂Mg 2 Si的形成能、电子结构和介电函数。结果表明,Al掺杂Mg 2 Si后, Al以替位杂质(Al替Mg位,即AlMg)或填隙杂质(Al位于晶胞间隙位,即Ali)的形式进入Mg 2 Si晶格。费米能级进入导带,体系呈n型导电。掺杂后体系的介电函数的实部和虚部在低频时比未掺杂时均增大,主要是由于晶格中的施主杂质Al离子束缚着附近的过剩电子,在外加交变电场的作用下,束缚在Al离子周围的电子要克服一定的势垒不断地往复运动造成松弛极化和损耗。另外,掺杂体系相对于未掺杂体系,介电函数的虚部在0.5 eV附近出现了一个额外的介电峰,该峰主要是由电子从价带跃迁到Al杂质能级引起的。计算结果为Mg 2 Si基光电子器件的设计和应用提供了理论依据。
英文摘要
    The electronic structure and dielectric properties of intrinsic and Al-doped Mg2Si have been investigated by the first principle plane-wave pseudopotential based on the density function theory. The calculated formation energy differences indicate that the most probable location of Al dopant is in magnesium sub-lattice, but one cannot rule out the interstitial position, which is only slightly less probable. The calculations of density of states (DOS) show that the Fermi level of Al-doped Mg 2 Si shifts into the conduction band and the system is n-type, which is consistent with the experimental observation. The calculated dielectric functions reveal that both the real part and the imaginary part of permittivity of the systems are increased with Al-doping, which is attributed that the electrons bounded to Al ions need to overcome a certain barriers during the reciprocating motion in alternating electric field . Besides the main dielectric imaginary peak (at 2.71 eV), an additional small peak (at 0.5 eV) emerges after Al-doping, which is ascribed to the transition of electrons from valence band to impurity level related to Al. The results provide the theoretical reference for the design and application of the Mg 2 Si-based optoelectronic devices.

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