Preparation And Properties Of Indium Tin Oxide Thin Films By High Power Impulse Magnetron Sputtering

Transparent Conductive Oxide（TCO）films have excellent optical and electrical properties in the visible wavelength range,which plays an important role in electronic devices such as display devices,organic light-emitting diodes,and solar cells.Indium Tin Oxide（ITO）is currently the most widely used TCO film.ITO films are usually prepared by the magnetron sputtering method in the industry.However,the quality of the films prepared by this method is poor at room temperatures or lower temperatures.High power impulse magnetron sputtering（HiPIMS）is an emerging method to prepare oxide thin films with high quality at room temperatures or lower temperatures.In this thesis,the ITO films are prepared by HiPIMS to investigate the influence of working pressure and pulse-average power on the film deposition mechanism and properties of the film.By optimizing the process parameters,low resistivity and high transmittance film were prepared.In addition,the resistivity of the films was further reduced by annealing in a nitrogen-hydrogen forming gas.The main results and conclusions of this thesis are as follows:（1）The working pressure significantly affects the components and crystallinity of ITO films.As the working pressure increases,the excitation/ionization level of the sputtered material increases.The film deposition rate decreases and the Sn/In atomic ratio and oxygen vacancy concentration in the film decreases,which leads to higher resistivity and higher transmittance and optical band gap of the film.（2）The pulse-average power significantly affects the components and grain orientation of ITO films.As the pulse-average power increases,the excitation/ionization level and energy of the sputtered material increase,the grain orientation of the film changes from<1 1 1>to<1 0 0>crystalline direction,the Sn/In atomic ratio and oxygen vacancy concentration in the film increase,which leads to higher carrier concentration in the film,lower film resistivity,higher transmittance,and lower optical bandgap.（3）By optimizing the working pressure and pulse-average power,the optimal film properties were obtained at a working pressure of 6×10^-2 Torr and pulse average power of 500 W process parameters:the lowest resistivity of 4.3×10^-3Ω·cm and the transmittance higher than 86%in the range of 380-780 nm.（4）To further reduce the resistivity of the films,the ITO films were annealed in a nitrogen-hydrogen forming gas.In the range of 300-700 ℃,the film resistivity gradually decreased with the increase of annealing temperature,and the optical properties were not significantly affected.At the same time,it was found that H played different roles in reducing the film resistivity in different temperature ranges.