Study Of Preparation And Optical Properties Of Anatase TiO₂ Thin Films By Atomic Layer Deposition Combined With Microwave Annealing

Energy shortage and environmental pollution are two major problems of human development.The advance in clean and renewable energy is the key way to solve this problem.Thus,exploring and developing new energy materials has become a research hotspot.As an important member of new energy materials,TiO₂ has good chemical stability,non-toxicity and unique optical and electrical properties,which is favored by researchers.In this paper,anatase TiO₂ were fabricated via atomic layer deposition combined with rapid photo thermal annealing and microwave annealing.The effects of different annealing technique on the phase structure,surface morphology and optical properties of TiO₂ films were studied.The details of this work are follows as:（1）Using TiCl₄ and H₂O as the precursors,the TiO₂ thin films with different cycle periods were fabricated via atomic layer deposition on the substrate of K9 optical glass,and then the samples were characterized.The results showed that under the temperature of 220°C,the deposition period of 1000 and 3000,respectively.The TiO₂ thin films with different thickness and different crystalline morphology could be prepared.（2）Using quartz glass and p-type silicon as the substrate,respectively.The deposition temperature was 120°C,the sputtering cycles were 3000.And then using atomic layer deposition and rapid thermal annealing technology to fabricated anatase TiO₂ thin film,investigated the different substrate and annealing temperature on the impact of thin film formation of anatase structure type.The XRD,Raman,SEM,EDS,XPS,AFM,ellipsometer and UV-vis were used for characterization.The results show that the higher annealing temperature is,the larger average grain size could have obtained;the surface roughness increases accordingly.The higher the refractive index and extinction coefficient,the lower the transmittance.And the lowest is 76.61%.When the annealing temperature is 600°C,the anatase TiO₂ film with good crystal quality can be fabricated on the p type silicon wafer substrate,and the optical band gap is about3.22 eV,which is close to the theoretical value of anatase TiO₂ optical band gap.（3）The amorphous TiO₂ thin film which deposited on the p-type silicon substrate was subjected to microwave annealing at 400°C,500°C,and 600°C,respectively.The samples were characterized by XRD,Raman,SEM,EDS and XPS and the effect of annealing temperature on the performance of the TiO₂ thin film was studied;The results showed that the non-thermal effect of microwave annealing on the p-type silicon wafer substrate was more conducive to the growth of the grains along the A（101）crystal surface of anatase TiO₂ thin film.When the annealing temperature was 600℃,the average grain size was the largest.Chemical composition analysis indicated that the thin film was close to the chemical ratio of TiO₂.（4）The amorphous TiO₂ thin film samples on quartz glass substrate were annealed at different temperatures by microwave materials science workstation,and the effects of different annealing temperatures on the thin film structure and optical properties were studied.The results showed that the 600°C annealed could get a better crystallization quality,but the crystallization of the quartz substrate was slightly worse than that of the p-type silicon substrate under the influence of microwave annealing selective heating.The refractive index and extinction coefficient increase with the increase of annealing temperature;the light transmittance decreases gradually,with the minimum of about 66.29%and the optical band gap of 3.21eV.