Preparation And Optoelectronic Properties Research On ZnO-based Infrared Transparent Conductive Film

In recent years,mine accidents have occurred frequently,which not only affects the national economy,but also threatens the safety of miners.As one of the most dangerous and destructive accidents,gas explosion has attracted widespread attention.The main gases that cause gas explosions are carbon monoxide and methane,and detecting the concentration of these two gases can prevent the accident to a great extent.However,the harsh environment under the mine severely interferes the stability and accuracy of the gas detector.As a part of the infrared window of the detector,the infrared transparent conductive film can play a role in dustproof,dehumidification,and protection of the detector,which has attracted the attention of researchers.In this thesis,ZnO-based transparent conductive films in the 3-5?m band are studied,including single-layer ZnO:Hf(HZO)films,ZnO:Mo(MZO)films and multilayer structure films.The research is based on National Natural Science Foundation of China-Research on a new type of infrared gas and carbon monoxide detector(No.61627823).Firstly,the HZO films were prepared on the sapphire substrate by radio frequency magnetron sputtering.The effects of oxygen flow rate and annealing conditions on film properties are analyzed.X-ray diffraction(XRD)analyzer test results show that the annealing treatment increases the grain size,reduces the spacing between crystal planes,and shifts the diffraction peak to the right.Oxygen content has a small effect on the grain size,but has a great impact on the intensity of the diffraction peak.Scanning electron microscopy(SEM)test results show a dense and uniform round granular structure.From the test results of the infrared Fourier spectroscopy(FTIR)analyzer,it can be seen that the average transmittance of the films in the 3-5?m range exceeds 80%.Hall test results show that when the oxygen flow rate is 0.6 sccm,the resistivity of the film is as low as 1.66'10^-2Wcm,and the corresponding carrier mobility and carrier concentration are 13.4 cm²V^-1s^-1 and2.82'10¹⁹cm^-3,respectively.Therefore,under the conditions of an oxygen flow rate of 0.6 sccm and an annealing temperature of 800°C,the prepared HZO film has the best microstructure and optoelectrical properties.Secondly,MZO films were prepared on ZnSe,sapphire and quartz substrates by magnetron sputtering.The effects of sputtering time,sputtering power,annealing condition and substrate on the properties of MZO films were studied.The results show that as the sputtering time increases from 90 min to 180 min,the(002)diffraction peak gradually becomes stronger and the grain size gradually increases.The film sputtered for 180 min has the best electrical properties,its resistivity is as low as 8.56'10^-3W×cm,and the carrier concentration and mobility are 8'10¹⁹cm^-3 and14.6 cm²V^-1s^-1,respectively.As the sputtering power increases from 50 W to 80 W,the(002)diffraction peak first strengthens and then weakens,and the transmittance and resistivity of the films also show a tendency to first decrease and then increase.When the power increases to 100W,both the film resistivity and the transmittance are reduced.The average grain size is maximum for the film prepared at a power of 100W.The annealing treatment reduced the transmittance of the films,but improved their electrical properties significantly.By comparing the optical properties of the films prepared on ZnSe,sapphire and quartz substrates,it is found that the films grown on ZnSe substrates show higher transmittance even at 18?m,but the cost of ZnSe substrates is higher.The cost of the quartz substrate is lower,but it has a more obvious absorption peak,and the transmission range is smaller.After comprehensive consideration,the sapphire substrate has more excellent performance.Finally,multilayer ZnO films were prepared.The effects of the number of layers and energy on the properties were studied.It is found that the multilayer films can also reduce the lattice gap of the films,thereby reducing the grain boundary scattering and increasing the transmittance of the films.It shows that the multilayer films can achieve similar effects as annealing treatment,but the performances of the annealing films are better than those of multilayer structure films.In order to eliminate the changes in optical phase and amplitude at the interface caused by uneven stress and refractive index,the films with the same thickness sputtered at low-power,high/low-power and high-power were compared.It is found that the surface of the films sputtered at low-power is relatively flat,but the time is the longest.While the films sputtered at high power have the fastest growth rate but more defects inside the films.Therefore,considering the time cost and quality,high/low power alternate sputtering is the best solution.