摘要
采用密度泛函理论框架下的第一性原理计算方法,利用广义梯度近似和Perdew-Burke-Ernzerdorf泛函,计算了不同Sn掺杂浓度下SZO(Sn∶ZnO)体系的电子结构与光学性质.研究了Sn掺杂浓度对SZO(Sn∶ZnO)的晶体结构、能带结构、电子态密度及光学性质的影响,并结合计算的能带结构和差分电荷密度对比分析了掺杂位置对计算结果的影响.研究结果表明,随着Sn掺杂浓度的增加,晶格常数c与a的比值变化很小,掺杂后晶胞没有发生畸变.掺杂体系的能量逐渐增大,稳定性减弱,且随着掺杂浓度的增加,带隙呈现先减小后增大的变化规律.掺杂后的SZO(Sn∶ZnO)成为间接带隙半导体,在导带底部附近出现了大量Sn原子贡献的导电载流子,明显提高了掺杂体系的电导率,并在费米能级附近与价带顶部之间出现一条由Sn原子贡献的杂质能级,能带结构呈现半填满状态,价带部分的电子态密度峰值向低能方向移动约1.5eV.同层掺杂的电子得失程度较大,带隙比相邻层掺杂和隔层掺杂时小.掺杂后吸收带边发生红移,材料对紫外光的吸收能力明显增强,介电常数虚部增大,主要跃迁峰向高能方向移动.计算结果表明SZO(Sn∶ZnO)是一种优良的透明导电薄膜材料.
The electronic structure and optical properties of Sn-doped ZnO for different doping concentrations are calculated by using the first-principles under the framework of density functional theory with the generalized gradient approximation and the Perdew-Burke-Ernzerdorf functions.The effect of doping concentration on the crystal structure,band structure,density of state,and optical properties is studied.Meanwhile,according to the calculated band structure and charge density of difference,the effect of doping site on the calculated results is investigated.The results show that with the increasing Sn doping concentration,the ratio of lattice constants c to ais stable,and the doped structure does not distort.The total energy of the doped system increases gradually,thus the stability weakens,and the band gap decreases first and then increases.The doped SZO（Sn∶ZnO）system becomes an indirect band gap semiconductor,and a large number of conductive carriers,which are contributed by the doped Sn atoms,are introduced to the bottom of the conduction band.As a result,the conductivity is significantly improved.Moreover,a V-shaped curve occurs between the Fermi level and the top of the valence band,which shows the characters of half-fill state.After doping,density of state peak of the valence band moves to the lower energy by about 1.5eV.The donated and received electrons in the same-layer doping are more than those in the neighbor-layer doping and the alternate-layer doping whereas the former band gap is smaller than the latter.The absorption edge has a red shift,and the ultraviolet absorption capacity is enhanced significantly.The imaginary part of the dielectric function increases,and the primary transition peaks shift to higher energy.The calculated results show thatSZO（Sn∶ZnO）is a good transparent conductive film.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2016年第7期204-212,共9页
Acta Optica Sinica
基金
陕西省高水平大学建设专项资金(2015SXTS02)
陕西省自然科学基金(2014JM2-5058)
延安大学研究生教育创新项目(2015-29)
