Study On Preparation Of TiN Thin Film Via Ammonia Reduction-nitridation Reaction

TiN thin films with high hardness,wear resistance,good optical properties,electrical conductivity and biocompatibility,which allow them to apply in various fields such as mechanics,tailored infrared coating,electronics,medical and surface enhanced Raman scattering,etc.The TiN thin films are often synthesized via hydrolytic sol-gel and reduction-nitridation reaction method.However,the raw material titanium alkoxide has high cost and fastly hydrolytic rate,and thus the product has relative low reductionnitridation efficiency.In contrast,nonhydrolytic sol-gel method has lower cost,facile process and higher reaction activity product.Therefore,the TiN thin films were prepared by ammonia reduction-nitridation reaction based on nonhydrolytic sol-gel process.Firstly,the ammonia reduction-nitridation process of TiO₂ films was studied by XRD,RAMAN,XPS,SEM,UV-VIS-NIR and 4PP.It was found that A-TiO₂ transformed into TiN at 700°C.With the temperature increasing,nitrogen content of the films are gradually close to pure TiN and the grain size increased with grain growth well.The reflectivity in near-infrared area of thin films is up to 70%,and the square resistance decreased then increased,and the least value is 43.5Ω/□ for the film synthesized at 900 °C.TiN films synthesized at 1000 °C have the best SERS activity with a detection limit of 10-6 M and enhancement factor of 4.8×103.Furtherly,the preparation process of TiN films is optimized.With increasing of PVP molecular weight,PVP dosage and coating times,the films become thicker and their square resistance decreases,their solar spectrum selective properties become better.Lowering heating rate,ammonia flow and prolonging holding time could improve the growth of TiN crystal,reduce the square resistance.The best parameters for SERS are as follows: 1.0g PVP of the molecular weight 1300000,pre-treatment at 600 °C,800ml/min ammonia flow,ammonia reduction-nitridation tempreture at 1000 °C for 2 h.Then,the influence of the second component（Al,Zr,Ni or Au）on TiN films is studied.Adding of Al and Zr dissolved into TiN crstal and refine TiN grains.Adding of Ni improves TiN to grow in preferred orientation of（200）,and thus the square resistance,SERS activity and solar spectrum selective properties are optimized.The adding of Au exists as elementary substance in TiN films,as a result,the square resistance and solar spectrum selective properties and SERS activity of TiN films are promoted.