Al，Ga掺杂ZnO电子结构和光电特性的第一性原理计算

采用基于密度泛函理论(DFT)框架下广义梯度近似(GGA)的PBE平面波超软赝势方法,计算了本征ZnO,Al掺杂ZnO(ZnAlO)和Ga掺杂ZnO(ZnGaO)的能带结构、态密度、复介电函数和复电导率. 其中Al或Ga是以替位杂质的形式进入ZnO晶格. 计算结果表明纤锌矿型ZnO,ZnAlO和ZnGaO都是直接带隙半导体材料,掺杂后ZnO的带隙变小,且ZnAlO的带隙略大于ZnGaO. 掺杂后ZnO的电子结构发生变化,费米能级由本征态时位于价带顶上移进入导带,ZnO表现为n型掺杂半导体材料,掺杂后在导带底出现大量由掺杂原子贡献的自由载流子—电子,明显提高了电导率和介电函数,改善了ZnO的导电性能,并且ZnAlO的导电性能要略好于ZnGaO.

First-principles calculation of electronic structure and optical properties of Al, Ga doped ZnO

We present the structural and electronic characterization of n-doped (Aluminium or Gallium) ZnO and the effect of the doping on the calculated optical properties. The fully-relaxed calculations have been made using the density functional theory (DFT) with generalized gradient approximation (GGA). Our results show that the wurtzite ZnAlO and ZnGaO are still direct band gap semiconductors as ZnO. And the ZnAlO has a slightly larger band gap than that of ZnGaO. With doping, the Al or Ga-donor levels appearing in the conduction band hybridize with the Oxygen-2p states and help decrease the resistivity of these doped systems as was found experimentally. The calculated optical properties show a small enhancement in the intensity close to the conduction band as a result of these Al or Ga levels. And the ZnAlO has a higher conductivity than ZnGaO.