First-Principles Study Of Doped ZnO

In this paper, electronic structure and optical properties of doped ZnO have beeninvestigated by the first-principles calculation based upon density functional theory,electronic structure include the band structure, electronic density of states, and opticalproperties, include dielectric function, absorption spectrum. Zinc oxide (ZnO) is a wide bandgap LED semiconductor material with extensive application prospect. the case of II-VI, havesome superior value. in photovoltaic and piezoelectric. with a wide direct band-gap of3.37eV and a high exciton binding energy of60meV at room temperature. The large excitonbinding energy(60meV) of which can ensure efficieni excitonic emission and ultraviolet (UV)luminescence at room temperature, become one of the major focuses in the research field ofsemiconductor short-wavelength devices. ZnO has a broad application prospects in ultravioletlight-emitting diodes, solar cells,liquid crystal displays, gas sensors, UV semiconductor lasers,and transparent conductice film. In the past decades, it was found that by doping differentelements into ZnO crystal can change and make its properties play a better performance.Electronic structure and optical properties of doped ZnO have been investigated by thefirst-principles calculation based upon density functional theory, electronic structure includethe band structure, electronic density of states and, optical properties, include dielectricfunction, absorption spectrum.We study band structure, total density of States, the partial density of States, the complexdielectric function, absorption spectrum properties In-Ga, In-Ta, Al-H Co doped ZnO,discussed the relationship between the microstructure and macro optical response. Bycomparison, our calculation results are in good agree with other theoretical and experimentalvalues. The results show that: after doping the emergence of a large number of contributionsby doping the free carrier-electrons in the conduction band bottom improve the electricalproperties of ZnO. In addition, the energy band be shift to lower energy direction, Fermi levelis in the conduction band, Jane and intensification.The results indicate that it was found that In-doping can cause decrease of Unit Cell volume and Ga-doping can cause increase of Unit Cell volume. The unit cell volumeexpansion after co-doping is decided by Ga. The doping introduces impurity energy level intothe forbidden band with its width increased a little, and The conductive ability is beenhanced.The ability of In-Ga Co-doped ZnO absorption bandedge red-shift was decreased in the rangeof visible light. And compared with the experimental and calculated values of IGZO films, theresults are accurate.The results indicate that it was found that In-doping can cause decrease of Unit Cell vol-ume and Ta-doping can cause increase of Unit Cell volume. The unit cell volume expansionafter co-doping is decided by Ta. The doping introduces impurity energy level into the forbid-dden band with its width increased a little, and The conductive ability is beenhanced. Thereare different wavelength absorption change in the visible light region, different wavelengthabsorption change.The results indicate that Al-doping and H-doping can cause increase of Unit Cell volume.The band gap width of the doped ZnO increased, and the conductive ability decreased. TheAl-H Co-doped ZnO absorption bandedge appeared blue-shift contrasting to the undopedZnO, and the ability of Al-H Co-doped ZnO absorptio increased in the range of visible light.The computational results are consistent with the available experimentaldata.