Fabrication Of Al-Doped ZnO Transparent Conductive Thin Films By Solvothermal Method

Recently，Al-doped ZnO transparent conductive films have drawn a great deal ofattention because of rich material, non-toxicity, high chemical stability and outstandingoptical and electrical properties. Presently, AZO thin films can be synthesized by severalmethods, the solvothermal technique of which is one of the most attractive for simpleequipment, low process costs and low temperature.Al-doped ZnO (AZO) thin films were successfully grown on common glass substratesusing a simple solvothermal method via the precursors of zinc acetate dihydrate (Zn(CH3COO)2·2H2O),monoethanolamine(MEA) with equal molar concentration with Zn(CH3COO)2·2H2O,aluminum chloride hexahydrate as doping, and methoxyethanol orethanol as solvent separately. The influence of temperature, depositing time, precursorliquid concentration, doping concentration on AZO thin films was investigated todetermine optimum reaction conditions using methoxyethanol and ethanol as solventseparately.In addition the properties of AZO films deposited on the glass substrates withseed layer were studied with ethanol as solvent. The structural, optical and electricalproperties of samples were characterized by means of X-ray diffraction (XRD), atomicforce microscopy (AFM), fluorescence spectrometer, UV-vis spectrophotometer andfour-point probe technique.The results indicate that all samples exhibit wurtzite structure with no peaks of otherimpurities detected. The films synthesized on the glass substrates with no seed layerpreferentially grow oriented along the c-axis; the electrical property with ethanol assolvent is more outstanding than methoxyethanol with the lowest sheet resistance of133.9k/□; however methoxyethanol as solvent is better at optical properties and structureof films than ethanol with higher average transmittance of92.41%and compact structureof smaller surface roughness. AZO thin films synthesized on the glass substrates with seedlayer by sol-gel exhibit different growth orientation with different reaction temperature.When reaction temperature is120℃, precursor liquid concentration is0.1mol/L,depositing time is18h and the doping concentration is3at%, the optical and electrical properties of the AZO film is optimal and it has an average transmittance of94.94%in thevisible range and the lowest sheet resistance of22.0MΩ/□.