Investigation On The Preparation And Electrical Properties Of Aluminum Doped Zinc Oxide Powder

ZnO is new direct band-gapⅡ-Ⅵsemiconductor material with a wide band-gap energyof3.37eV and an exciton binding energy of60meV at room temperature. By doping the Ⅲgroup elements (such as Al, Ga, In), the conductivity of ZnO can be improved by severalorders of magnitude, which is a typical material of the transparent conductive oxide (TCO).Compared with In2O3:Sn (ITO), SnO2:Sb (ATO), SnO2:F (FTO) and other TCO materials，dueto the Al-doped ZnO (AZO) has the advantages of low cost, non-toxic and high conductivity,and therefore it is one of the most hope commercial application of TCO material.In this paper，ZnO and AZO nano-powders were respectively prepared by solvothermalmethod, sol-gel method, sol-gel hydrothermal method and other chemical method. ThenTransmission electron microscopy (TEM), Scanning electron microscopy (SEM),Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Electron microprobeanalysis (EPMA) and other means of analysis were used to characterize nanomaterials size,structure, morphology and electrical properties. The main contents are as follows:(1) ZnO nano-powder was prepared by solvothermal method, The results showed that theexistence of OH-in Solvothermal method have a significant impact on polar growth of AZOnanocrystallin, when the addition NaOH in reaction solution, AZO nano-powders generated isrod-like, without the addition of NaOH, AZO nano-powders generated is spherical-like.(2) AZO nanorods were synthesized by solvothermal method. With the increase of Al iondoping amount, diameter and length of AZO nanorod became thicker and shorter, the reasonmay be that lattice distortion caused by Al ions substituted Zn ions hinder the polar growth ofZnO; With the increase of Al ion doping amount, the AZO body resistance first significantdecreases, and then slowly increase, when Al doping amount was2%, the minimum volumeresistivity is6.47x10~2Ω·cm.(3) AZO nanorods were prepared by sol-gel method. With the increase of doped Al ioncontent, the AZO body resistance first significant decreases, and then slowly increase, whenAl doping amount was0.5%, the minimum volume resistivity is5.15x10~2Ω cm, which ismuch larger than volume resistivity of AZO synthesized by solvothermal method. The reason may be due to the partial pressure of oxygen is very high when sintering, it inhibits the loss ofoxygen and formation of non-stoichiometric ZnO as well as the number of positively chargedcenters(), lead to reduction in the number of charge carriers (electrons)of AZO crystal.(4) AZO nano-powders were synthesized by novel sol-gel hydrothermal method, Withthe Al doping concentration increases in the NaOH content of mineralizing agent for2g,morphology of AZO nano-crystal changes little, when the Al doping amount is2%, thevolume resistivity is minimal. When the Al concentration is2%, to study the effect of NaOHcontent on the morphology and electrical properties of AZO, the results show that with theincrease of NaOH content, AZO nanocrystals turned by a spherical into stick and then into asheet-like composed of globular, and its resistance to reduce and then increase, when theNaOH content is4g, the lowest resistivity of AZO nano-rod is4.69×10~2Ω·cm. The optimumconditions for the preparation of Al doped ZnO nanopowders by sol-gel hydrothermal method:Al doping amount is2%, the content of NaOH is4g.