The Effect Of PECVD Deposition Parameters On The Transition And Microstructure From Amorphous Silicon To Microcrystalline Silicon Thin Films

Microcrystalline silicon thin film material has both high light absorption coefficient of amorphous silicon thin film materials,but also has high stability of crystalline silicon materials,long life of carrier,and the little light recession effect.So they have been recognized by domestic and foreign markets.For research of microcrystalline silicon thin film material,usually at home and abroad are using plasma enhanced chemical vapor deposition?PECVD?technique preparation technology.It has the characteristics of simple equipment,mature technology,low temperature and large area uniformity,good materials and a forming cell and low cost.In this paper,with reference to the research results at home and abroad,the performance and growth mechanism of silicon-based thin films were analyzed,and the preparation methods and deposition process of silicon-based thin films were tentatively explored,and the effect of PECVD deposition on the transformation of amorphous silicon to microcrystalline silicon and microstructure was studied.The paper adopts Radio frequency?13.56MHz?PECVD system to prepare silicon film materials.The sample films were characterized by X-ray diffraction UV-visible transmission,infrared Fourier spectrum and Raman spectroscopy.The effects of silane concentration,RF power,deposition temperature,and deposition pressure on the conversion of amorphous silicon to microcrystalline silicon were explored,and their influence on the structural properties and optical properties of the material was explored.The results of the research in this paper show that:1.Hydrogenated silicon-based thin film materials were prepared by adopting a plasma enhanced chemical vapor deposition?PECVD?system,taking SiH₄ and H₂ as a reaction gas source,and changing radio frequency?Rf?power and silane concentration.The effects of deposition parameters on the microstructure of Si-based thin film materials were studied.Sample materials were characterized by infrared absorption spectrum,ultraviolet-visible?UV-Vis?spectra and X-ray?XRD?diffraction spectra.The results showed that,with the increase of the RF power,hydrogen content in the film increased accordingly,while optical band gap increased first,then decreased.When the silane concentration is reduced,the optical band gap of the thin film materials decreased accordingly,and the thin film materials transferred from amorphous silicon thin film materials to microcrystalline silicon thin film materials.Meanwhile,a grain size of the thin film materials along a?111?direction reached 10.92nm.Therefore,under the conditions of higher deposition pressure,higher RF power and low silane concentration,the quality of the Si-based thin film materials can be effectively improved.Therefore,in the high pressure and RF power under the condition of low silane concentration can effectively optimize and improve the quality of the silicon thin film materials,from amorphous silicon thin film to make the transition to microcrystalline silicon thin film materials2.Using a PECVD deposition system,with SiH₄ and H₂ as the action gas source,microcrystalline silicon thin film materials were prepared by changing the substrate temperature.The results show that as the substrate temperature increases,the hydrogen content in the films gradually decreases,and the structural factor shows the opposite trend.The crystal phase of the film shows a gradual transition from amorphous to microcrystalline,and when the temperature is at 200°C,the film crystallization rate reached a maximum of 68.7%.The optical band gap exhibits a monotonically decreasing law.Finally,it is concluded that,under conditions where certain other conditions are optimized,the substrate temperature of 200?is the optimum deposition temperature for the transition from the amorphous silicon film to the microcrystalline silicon film material.3.By plasma chemical vapor deposition system,silane and hydrogen were used as the gas source,The microstructure of crystalline silicon thin film material was studied by changing the deposition pressure.The results show that the optical band gap of thin film sample decreases with increasing deposition pressure,and the film gradually transforms from amorphous to microcrystalline state,and the crystallization rate of thin film sample increases from 51.6%to 62.8%.The thin film hydrogen content decreases and the structure factor increases,and the surface of the film sample presents some inhomogeneity.