Al:ZnO的电子性质、光学性质及电性质的理论研究

Theoretical study on electronic,optical and electrical properties of Al:ZnO

应用第一原理方法研究了n型Al:ZnO块体材料的几何结构、能带、态密度分布、电子分布、光学性质和电性质。分析结果表明:ZnO晶胞略有收缩,晶胞a,b,c轴均减小;掺杂ZnO块体材料导带和价带之间具有0.85e V的直接带隙,能隙宽度减小;态密度分布在费米能级附近大大增加,这些状态主要由Als、Alp、Zns、Op构成,且Zns、Als、Alp和Op之间存在着强偶合相互作用,其中Zns态、Als态和Alp态电子对导带贡献最大,Al:ZnO块体材料呈现宽的吸收范围和高的吸收率。Al:ZnO块材的Zns-Als-Op电子之间的转移构成电子迁移,Als电子参与导电;其价带有效质量相对较大,导带有效质量相对较小。

The geometrical structure, band structure, density of states, the charge populations, optical proper-ties as well as the electrical transport properties of the A1 doped wurrite type ZnO bulk materials have been in- vestigated by the plane wave ultro-soft seudo-potentials based on the density functional theory calculations. The calculational results show that the a, b and the c axis decreases with the cell shrinkage. The A1 doped wurrite type ZnO has approximately 0.85 eV direct band gap between two energy bands, the energy gap for carriers to surpass is decreased, the type of semiconductor is not changed. The density of states near Fermi level is increased, the energy bands near Fermi level are composed by Als, Alp, Zns, Op state electrons, and there are strong interactions between the Zns, Als, Alp and the Op state electrons. Meanwhile, the density of state near the conduction bands are mainly contributed by the Zns, A1 and the Alp state electrons. The A1 doped ZnO exsibits wider and higher energy range of absorptivity. The analyzing results of the electrical trans- port properties show that the carrier transport is accomplished by Zns -Als -Op state electrons between conduc- tion bands and valance bands rather than the undoped system in which the Znp-Op state electrons are responsi- ble for the process between the valance bands and the conduction bands. The Als play important role in the carrier transport process. The carriers near Fermi level for the doped system is weighter than that of the undo- ped system, the carriers within the valence bands have heavier effective mass and the carriers within the con- duction band have lighter effective mass for the A1 doped wurrite type ZnO.