| As an important optoelectronic information material,ZnO-based tansparent conductive oxide thin film is a promising alternative to ITO thin films,due to some advantages,such as its abundance in nature,lower cost,non-toxic and the better stability in hydrogen plasma.Compared to ZnO:Al?AZO?thin films,which have been studied a lot up to now,Ga is a kind of doping element,of which atomic radius and ionic radius are closer to Zn's,and the bond length of Ga-O is also closer to Zn-O.In this way,Ga doped ZnO thin films can be less lattice-distorted.What's more,ZnO:Ga is more avoidable in the appearance of the Oxidation phase?Ga2O3?,which is beneficial to obtain superior photoelectric properties.In addition,study on the preparation and performance optimization of the films under room temperature will beneficial to expand the application fields on flexible substrate.In this paper,Ga2O3:ZnO?3 wt.%:97 wt.%?ceramic target has been used to prepareZnO:Ga?GZO,forshort?thinfilmsbyRadioFrequency?RF?magnetron sputtering.First of all,the change rules of photoelectric properties of GZO thin films deposited at different substrate temperatures have been studied.And then,research on the influence of sputtering time,power and pressure to GZO thin films will also be made,with the purpose of optimizing all sputtering parameters at room temperature.Finally,the impacts of the sputtering time of ZnO buffer layer on thestructuralandphotoelectricpropertiesofGZOfilmshavebeen explored.Representation and analysis of GZO thin films are presented as the following conclusions via XRD,SEM,XPS,four-probe,step profiler and UV-visible spectrophotometer,etc.:?1?All of the GZO thin films prepared in this paper showed n-typed degenerate semiconductors,whose band gaps were all larger than that of intrinsic semiconductor ZnO?3.30 eV?.All samples were polycrystalline with the hexagonal crystal structure and had a strongly preferred orientation of c axis without any Ga2O3 phase.All the GZO films had a good crystallization,with the grain size ranging from 19 nm to 32 nm.?2?Different deposition temperatures,which were set with RT,80??140?and 200?,would affect the crystallization property of the GZO films obviously,which showed in the form of changes on the photoelectric properties.While GZO films were deposited for 30 min with the power and pressure of 200 W and 0.7Pa,the most compact structure and the best crystallization property of GZO sample were obtained at the deposited temperature of 140?,of which its conductivity was also the best accordingly.The lowest square resistance and resistivity respectively were 41?/?and 2.6×10-3?×cm,and the peak value of transmittance in the visible region was up to 90%.?3?The crystallization property of the GZO films would get better with the increase of sputtering time,and the largest grain size was 32 nm,the lowest square resistance and resistivity respectively were 14?/?and 1.20×10-3?×cm,which were all obtained when it was sputtered for 50 minutes.Whereas,the transmittance of GZO thin films decreased with the increasing sputtering time,and the infrared reflectance performed on the contrary.The integrated performance was gotten when the sputtering time was 30 minutes,which the figure of merit was 4.30×10-3?-1.The strongest diffraction peak in XRD spectra and the most excellent properties of GZO film were obtained with the power of 250 W and the pressure of 0.7 Pa,would not higher or lower.?4?Inserting a ZnO buffer layer properly would reduce the inner stress of films and increase the properties obviously,and would barely affect the transmittance in the visible region.The lowest inner stress was obtained with+0.06518 GPa when the sputtering time of ZnO was 10 min,and the lowest sheet resistance with 22?/?was gotten at the meanwhile,which is lower than that of GZO thin film without buffer layers?32?/??. |
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