Pld Prepared Zno Transparent Conductive Film And Its Performance Study

TCO films have been widely used in many fields, such as LCD, solar cells. With the development of preparation methods and polymer substrates, TCO films will have wider application and development space.ZnO is a direct band gap wide band II-VI compound semiconductor material. Its stability crystal structure is hexagonal wurtzite structure at room temperature,band gap is about3.37eV, exciton binding energy is up to60meV. As an intrinsic n-type semiconductor material, we can get a higher electron density, low resistivity, while in the visible region can maintain a high transmission rate, if we dope ZnO by donor (such as Al,Ga, Zr etc.). And compared to other TCO materials such as ITO, ZnO has the following main advantages:abundant, inexpensive, non-toxic and environmentally friendly, good thermal stability, easy-to-growth processing. ZnO and doped ZnO materials have been widely used in UV detectors, light-emitting devices, solar cells, piezoelectric sensors, thin-film optical waveguide and transparent conductive film and other fields. Actually transparent conductive films based ZnO are attracting wide attention in recent years.The main contents of this paper and the results are as follows:1) Overview the development history and applications of the transparent conductive oxide thin films and made some describe of the preparation methods, and highlights describe the technique of pulsed laser deposition and the testing means and methods of analysis as well as the related experimental equipment.2) Use high-purity ZnO,Ga2O3powder as raw material, by optimizing the sintering process to prepare a smooth, homogeneous, dense ZnO:Ga target by the use of solid-phase sintering at atmospheric pressure. Studied the relationship between the forming pressure of target and the target surface morphology.And studied the relationship between resistivity with sintering temperature.The results showed that:the best forming pressure is3MPa, when the target had the least defect; the minimum resistivity1.24×10-3Ω·cm was obtained,when the sintering temperature was1200℃.3) ZnO:Ga transparent conductive films were prepared by PLD. The structural, electrical and optical properties of the ZnO:Ga films were investigated in terms of the substrate temperature. With the substrate temperature changed from250℃～650℃, the (002) peak was significantly increased and the grain increases. The lowest resistivity of8.56×10-4Ω·cm,carrier concentration3×1020cm-3,and mobility45cm2V-1s-1was obtained when substrate temperature for450℃. The transmittance of the ZnO:Ga films in the visible range was over87%.The structural, electrical and optical properties of the ZnO:Ga films were investigated in terms of the oxygen partial pressure.The results showed that:the depoed thin films are c-axis (002) preferred orientation of hexagonal polycrystalline structure, oxygen partial pressure have a greater impact on the size of the grain size of the films. The ZnO:Ga thin films with the maximum grain size when depoed at the oxygen partial pressure of0.5Pa. The films had excellent optical performance, and the oxygen partial pressure had little impact on film visible light transmittance,the average transmittance of the film was over90%. Resistivity of the film decreaseed with the oxygen partial pressure increases first and then increased and the lowest resistivity was3.73×10-4Ω·cm.To improve the prepared films we go on to study the annealing temperature on films structure and optical properties. The results showed that:with the annealing temperature increased from300℃to600℃in the process, the film c-axis (002) preferred orientation is more obvious, the film FWHM further narrow, more smooth and dense. The lowest resistivity1.62×10-4Ω·cm, carrier concentration8.52×10020cm-3,and mobility55cm2V-1s-1were obtained when annealing temperature was500℃.Average visible light transmittance is over90%, the band gap of the films are up to3.77eV.4) In-Nb doped ZnO transparent conductive films were prepared by PLD. The structural, electrical and optical properties of the films were investigated in terms of the substrate temperature. The results showed that:the film prepared with a clear c-axis preferred orientation with the substrate temperature changed from100℃to500℃.The lowest resistivity5.07×10-4Ω·cm, carrier concentration6.12×1020cm-3,and mobility13cm2V-1s-1were obtained when the substrate temperature was300℃.Average visible light transmittance is over92%.