Metal Ions Doped Zno First Principles Calculation And Preparation Of Transparent Conductive Thin Film Research

ZnO film is aⅡ-Ⅵdirect compound semiconductor with wide band gap energy of 3.37eV and a exaction binding energy 60meV at room temperature. ZnO thin film is used widely and effectively in the fields of surface acoustic wave devices, solar cell, gas sensors, varistors and so on because of its excellent piezoelectrical performance. It also has the tremendous potential applications for ultraviolet detectors, LED, LD. Al-doped ZnO (ZAO) thin films are emerging as an alternative potential candidate for ITO (Sn-doped In2O3) flims recently not only because of their comparable optical and electrical properties to ITO films, but also because of their higher thermal and chemical stability under the exposure to hydrogen plasma than ITO. P-type doping of ZnO thin films which attract lots of attention.In this paper, the various growth techniques of ZnO films and the progress in the internal and overseas researches of ZnO were reviewed.The quantum mechanics First principle elementary theory was introduced, especially the density arbitrary function theory, and CASTEP software synopsis.The software of calculations was called Material Studio with the help of a powerful package. A method using first-principles and pseudopotentials which are based on the density functional theory was applied to calculate the crystal structure, the band structure and density of state of ZnO doped with metal ions of monovalent, divalet, trivalent and RE. The calculated results show that firstly, there is the donor level(the n-type semiconductor) in the ZnO energy structure which was doped Al3+.It forms the energy band gap broaden.In addition,after doping Al3+in ZnO,it is possible to occur blue move effection.With the increasing doping quantities,the energy band and the impurity level both became broarder. After doping trivalent metal ions, ZnO super-cell volume is expanded.Things are nearly the same with doping Ga and In ions into ZnO.Comparing the three doping methods, we have found that Al-doped ZnO conductive ability is the best of the three trivalent metal ions that were doped into ZnO.What is more, Al-doped ZnO is the most suitable transparent conductive material of the three. Y-doped will impact the band and the density of state greatly. It is probably because that the radius of Y3+ will enlarge the crystal distortion and may even undermine the ZnO crystal structure. Secondly, Ag ions-doped can lead to expansion of the lattice.When Ag takes the place of the Zn position, a deep acceptor level(0.452eV) appeared. Also, when Ag occupies gap position, Ag acts as the donor level. So it can create compensation to the acceptor impurity level. Therefore, it is difficult to obtain P-type the ZnO material by doping Ag. When Cu takes the place of the Zn position, a deep acceptor level (0.258eV) appeared. Also, when Cu occupies gap position, Ag acts as the donor level. So it can create compensation to the acceptor impurity level. Ag ions-doped ZnO is more difficult to obtain P-type than Cu ions-doped. I A ions-doped can lead to expansion of the lattice.When I A ions take the place of the Zn position, a acceptor level Li+(0.682eV),Na+(0.513eV) and K+(0.078eV) appeared. Li+and Na+ ions-doped forms the deep acceptor level. K+ ions-doped forms the shallow acceptor level, but the system stability is bad, does not favor enhances the K solid solubility.Then I A metallic ions-doped is also difficult to obtain the P semiconductor. I B ions-doped ZnO must surpass I A ions-doped obtains the P semiconductor. Thirdly, Ag-Al ions co-doped ZnO indicate that along with the Ag+ doping quantity increase, a Fermi level enters the valence band to be deeper, can the crack strict, the impurity energy level becomes narrower. So this is helpful in realizes the ZnO P semiconductor. Fourly, we caculated different concentrations of Mn-doped and Cd-doped, the results show that with the increasing concentration of Cd-doped, the dielectric is narrower.And it is on the contrary for Mn-doped. After Nb-doped, the results show that the higher metal prices state are, the better performance its electrical conductivityn is.In a word, along with the ascension of metal valent state, the impurity energy level will be able to reduce,which will increase the current carrier density.Thus the situation will enhance the electric conductivity of ZnO. Secondly, the gap energy can be able to be nearer to the energy level of oxide compounds doped with ion along with the increase quantities of the doping density. Finally, with the ascension of metal valent state the impurity energy level will reduce.In this paper, the ZnO thin films were prepared on glass substrate (microscope slides) by Sol-Gel process from ethanol and 2-methoxyethanol solution was prepared by Zinc acetate as premonitormonoe then olamine as stabilizer and glacial acet homogenous as activator. The transparent and conductive, polycrystalline ZnO thin film was made finally by dipping coating and spin coating conducted for film-plate on substrate, drying, pre-heat-treatment, and anealing.X-ray diffraction (XRD), scanning electron microscope (SEM), Energy dispersive spectrum(EDS), four point resistivity test system and ultraviolet-visible (UVS) spectrum were used to characterize the crystallization behavior, orientation and surface morphology of the ZnO thin films. It is revealed that the thin films with strongly preferred orientation of C-axis perpendicular to the substrate surface of which surface was homogenous, dense and crackfree were the crystalline phase of hexagonal wurtzite. The thin film was composed of plentiful meshy crystal. The average transmittance of thin film in visible region was above 80%. The optical band gap was widened with the increase of Al/Zn molar ratio. The ZnO:Al films resistivity was found to be 4.88×10-1～2.24×10-4Ω·cm. The ZnO:Li thin films has the same crystalline phase of hexagonal wurtzite and preferred orientation of C-axis as ZnO:Al. Secondly,ZnO:Li films resistivity was biger than ZnO:Al's which was found to be 90～1.53×10-1Ω·cm. Prepared technical parameters were optimized by L9(34)experiment analysis.Thirdly, ZnO:Y films have hexagonal lead-zinz mine structure at same,and causes the crystal lattice to have the distortion.The ionic radius big ion to be very difficult to enter the gap position. Fourly, the optimization parameter that is 15 layers, 2%atm (Al3+),250℃(pre-heating temperature),600℃(annealing temperature) was fished out by large numbers of experiments. Lastly, the doping measures Ag-Al co-doped the ZnO thin film is good performance and structure such as Ag-Al is the 3%, Ag:Al mole compared to is 10:1, preheating temperature for 180℃and annealing temperature for 550℃.The relationship between the ZnO:Al films resistivity and the meshy surface was researched. Also the result proved that the denser of the meshy surface is the better of the ZnO:Al films resistivity will be.