摘要
采用密度泛函理论计算分析的方法系统研究了Al掺杂TiO_2基晶体材料的电子结构和光学性质.结果表明,本征Ti02材料具有直接带隙型能带,其带隙宽度为2.438 eV,Al掺杂TiO_2材料同样具有直接带隙型能带,其带隙宽度降低至2.329 eV.本征TiO_2与Al掺杂的TiO_2材料均含有五个子能带,但是Al掺杂TiO_2材料子能带位置发生改变.Al掺杂在Ti02材料价带中引入大量新的能级,降低了费米能级上的态密度,Al掺杂为n型掺杂.对于Al掺杂TiO_2材料来说,s态电子和p态电子主要在Al掺杂TiO_2材料的带内跃迁过程起较大的作用.Al掺杂的TiO_2材料最强的介电吸收峰在320 nm附近,Al掺杂拓展了TiO_2材料的光吸收范围,其介电吸收能量范围向长波方向移动.本征TiO_2及Al掺杂TiO_2材料在1000 nm以下波长的折射率曲线相似.Al掺杂TiO_2材料在500 nm以下的折射率较本征TiO_2材料降低,而500 nm以上折射率较本征TiO_2材料增大.
The electronic structure and optical properties of the Al-doped TiO_2 crystalline material is investigated by density functional theory calculation method. The results show that the intrinsic TiO_2 has direct energy gap of 2.438 eV, the Al-doped TiO_2 has decreased direct energy gap of 2.329 eV. The intrinsic TiO_2 and the Al-doped TiO_2 both have five sub-bands, but the regions that the sub-band location has changed for the Al-doped TiO_2. The Al has introduced many new bands within the valance bands; the density of states at Fermi level has been also decreased. The Al-doping is n type doping for the TiO_2 material. The s and p electrons contribute to the mobility of carriers within the bands. The dielectric absorption peak of Al-doped TiO_2 locates at 320 nm, the absorption region is widened by Al-doping and the absorption region has moved to long wave light area. Both systems have the similar refractive index curves under 1000 nm. The refractive index of Al-doped TiO_2 is decreased under 500 nm, and it is increased above500 nm comparing with the intrinsic TiO_2.
引文
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