Analysis Of The Optical Properties Of The Transparent Conductive Film Based On Different Substrates

In the field of photoelectric science and technology, the highly visible light transmittance(Tavg>80%) and low resistivity (ρ<10-3Ω·cm) of transparentconductive thin-filmmaterials are usedin wide range, such as LCD, touch screen and solar cell etc. The optical properties of the transparentconductive thin film is largely depended on the material properties of the film’s substrate, and it isimportant to study the impact of the substrates on the optical properties of the transparent conductivefilm. Gold is selected as the transparent conductive material and deposited on different substratesby DC sputtering, because the performance of gold is chemically stable and often manifests opticalisotropy and represents the dependence of film’s optical properties on substrate materials. Theresults of these study have a certain significance to the preparation of transparent conductive films,especially those claim some special optical requirements. The main content is as follows.Firstly, the DC sputtering method is used to prepare transparent conductive gold films onSilicon and glass and common flexible substrate PI film respectively. The variation of thethicknesses of transparent conductive gold films which were prepared on different sputteringconditions, is measured by ellipsometer, the square resistance is measured by four-point probemethod, and the surface morphology is characterized by SEM. The results show that: the thicknessof the transparent conductive gold film increases with the increase of sputtering time and sputteringcurrent; the square resistance decreases with the increase of the thickness of the gold film; thesurface morphology becomes more continuous with the increase of the thickness. By analyzing thevariation of the film thickness with current and time, we try to explore the formation mechanism ofthe DC sputtering deposition.Secondly, by controlling the different incident angles and incident directions (calibrate theincident light’s degree rotating around the normal axle of film surface) of an ellipsometer, and wemeasure the changes of optical properties of different substrates and the transparent conductive goldfilm on them in visible range, and then explore the impact of the substrates on the optical propertiesof gold film. Detailed results are as follows: (1) The selected Si substrate with polishing process is single-crystal silicon, and the single-crystal silicon is isotropic material. Thin film formed by single atom of gold also performed asisotropic, and optical parameters of gold film deposited to the Si substrate not change muchunder different incident angles and incident directions, and the same time can determine theoptical properties of the transparent conductive gold film to a certain extent.(2) The selected glass substrate is an isotropic material, but its surface roughness is largebecause it’s not polishing. The optical parameters of the glass surface before and afterdepositing the transparent conductive film changes significantly under different incident anglesand incident directions. This result not only further determine the optical properties oftransparent conductive gold film, and also can explore the impact of the glass substrate on theoptical properties of gold film.(3) The selected PI substrate is a typical anisotropic organic polymer material, and the PI filmsurface roughness is also large. The optical parameters of the PI substrate changed significantlyunder different incident angles and incident directions. The results show that deposit the goldon PI film can explore the effect of an anisotropic substrate to the optical properties oftransparent conductive gold film.