| Transparent conducting oxides (TCOs) are a class of materials that can exhibitsimultaneous conductivity and transparency. This behavior makes TCOs useful for a wide rangeof practical applications including flat-panel displays, solar cells, gas sensors, thin film resistors,organic light emitting diodes (OLEDs), smart windows and so on. Recently, there has beenconsiderable interest in the application of films deposited on polymer substrates becausepolymer substrates are lightweight and flexible. TCO films deposited on polymer substrates canbe widely used in flexible optoelectronic devices, flexible displays, flexible thin film solar cells.In this paper, the Ga2O3/Cu/ITO multilayer films on the polyethylene terephthalate (PET)substrates were prepared at room temperature. The Ga2O3buffer layer is introduced to make thepolymer substrate surface smoother and reduce the level of vapor and oxygen diffusion. Theoptical and electrical properties of samples were studied by changing the thickness of Ga2O3, Cuand ITO. Meanwhile, the effects of annealing temperature, annealing time and storage time onthe multilayer films were studied.Firstly, the effect of the Cu layer thickness on the properties of the Ga2O3(20nm)/Cu film was investigated. The best figure of merit of1.15×10-3-1is obtained when thethickness of Cu layer is4.2nm. Secondly, the property of the Ga2O3/Cu(4.2nm)/ITO(30nm) multilayer films was investigated at different Ga2O3layer thicknesses. The surface morphology, the transmission and the electrical properties can be improved by an appropriate Ga2O3buffer layer thickness. The maximum transmission of86%, the sheet resistance of45/sq and the figure of merit of3.96×10-3-1were achieved for Ga2O3(15nm)/Cu(4.2nm)/ITO(30nm) films.The optical transmission and the sheet resistance of the Ga2O3(15nm)/Cu/ITO(30nm) filmsare mainly depended on the Cu layer. When the thickness of Cu layer is3.7nm, the maximumtransmission of87.6%, the sheet resistance of50/sq and the figure of merit of4.53×10-3-1were obtained for the Ga2O3/Cu/ITO films.When the ITO layer within a certain thickness, the optical transmission of theGa2O3(20nm)/Cu(4.2nm)/ITO films increase slightly. The sheet resistance of the multilayerfilms increases initially and then decreases with increasing ITO layer thickness (≤30nm) and the sheet resistance show a downward trend with the further increase of the ITO layer thickness.With the increase of annealing temperature and annealing time, the defects in the samples arereduced and the crystallization quality is improved. The optical transmission of theGa2O3/Cu/ITO films is increased. And, the electrical properties of the Ga2O3/Cu/ITO films arealso improved within a certain range of the annealing temperature and annealing time. So wecan conclude that an appropriate annealing treatment can improve the optical and electricalproperties of thin films. |
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