基于第一性原理计算的共掺型p型ZnO光电学特性对比研究

采用基于DFT的第一性原理研究了本征ZnO和Ag单掺、Ag-F（或N）共掺ZnO体系的晶格结构、电子结构和光学性质。结果表明：各掺杂体系与本征ZnO相比晶格常数a、c和晶胞体积基本都有所增大;虽然N3-离子半径高于F-,但Zn15AgO15N晶胞体积低于Zn15AgO15 F,是由于Zn15AgO15N体系的Ag-O和N-Zn键长均低于Zn15AgO15 F体系的Ag-O和F-Zn键长,且Zn15AgO15 N体系结构更稳定;Zn15AgO15N体系中杂质能级有所降低,所需电离能降低,杂质更易电离,Ag4d、N2d和O2p态电子在VBM处形成杂化;Zn15AgO15N在紫外光区和可见光区的吸收率和反射率上有较大的增强。Zn15AgO15 F体系由于施主-受主的补偿效应,导致了总体结构的不导电,可以看出Ag-F共掺不适合用于ZnO的p型转化,而Ag-N成功实现了浅施主能级的p型转化,且具有较好的光电学特性。这为ZnO在紫外短波长光电子器件上的应用提供了一定的依据。

Comparative study on the photoelectric properties of co-doped p-type ZnO based on first principles calculation

The first principles based on density functional theory (DFT) were used to research the lattice structure, electronic structure and optical properties of pure ZnO and Ag mono-doped and Ag-F(or N) co-doped ZnO systems. The results show that compared with pure ZnO, the lattice constants a, c and supercell volume of each doped system are basically increased. Although the radius of N3- ions is higher than that of F-, the cell volume of Zn15AgO15N is lower than that of Zn15AgO15F. This is because the Ag-O and N-Zn bond lengths of Zn15AgO15N system are lower than the Ag-O and F-Zn bond lengths of Zn15AgO15F system, and the structure of Zn15AgO15N is more stable. In Zn15AgO15N system, the impurity level is reduced, which leading to a lower ionization energy, the impurity is easier to ionize. Meanwhile, the electrons of Ag4d, N2d and O2p states are hybridized at VBM. The absorption coefficient and reflectivity of Zn15AgO15N in ultraviolet and visible regions are enhanced greatly. Due to the compensation effect of donor-acceptor, the overall structure of Zn15AgO15F system is not conductive, it can be seen that the Ag-F co-doping is not suitable for p-type transformation of ZnO. However, Ag-N co-doping successfully obtained p-type ZnO with shallow donor level and good photoelectric properties. This may provide a certain basis for the application of ZnO in ultraviolet short wavelength photoelectronic devices.