Research On The Moisture-sensitive Properties Of Porous TiO₂ Composite Films Based On Silicon Nanoporous Column Arrays

The humidity of the air is an important parameter,which is closely related to industry,agriculture and people's lives,so it makes sense to accurately detect humidity and control it.In the development and research of humidity sensor,the preparation of sensitive materials has become an important research direction.There are many ways to improve the performance of a humidity sensor.From a microstructural point of view,increasing the specific surface area is one of the most effective ways to improve it.TiO₂ sol and SnO₂ were prepared by sol-gel method using butyl titanate?[CH₃?CH₂?₃O]₄Ti?,stannous chloride?SnCl₂·2H₂O?as precursor and anhydrous ethanol as solvent.The sol is prepared by spin coating and calcination annealing to prepare a pure phase thin film.In order to increase the specific surface area of the thin film,polyethylene glycol?PEG?was added as a template to prepare a TiO₂ thin film with a porous structure.By changing the experimental conditions,the molecular weight/content of the templating agent and the number of spin coatings were optimized to obtain different thin film structures.It was found that the addition of diethanolamine?HN?CH₂CH₂OH?₂?and PEG is more favorable for the formation of porous structures.To further improve the performance of the humidity sensor,TiO₂ and SnO₂ sol were composited in different volume ratios to obtain a porous thin film,and a silicon nanoporous column array structure was used as a substrate to prepare a humidity sensor.The results show that the moisture sensitivity of composite thin film components is greatly improved compared with pure phase thin films.In composite thin film components,thin film components with a tin to tin volume ratio of 9:1 are the most outstanding.The component has the advantages of high sensitivity,relatively good response characteristics,and good hysteresis characteristics.Compared with pure phase SnO₂ and TiO₂ thin film components,the capacitance values are increased by 4 orders of magnitude and 2 orders of magnitude respectively.,the sensitivity was increased by9.5 times and 1.6 times,the response time was shortened by 63 s and 8 s,respectively,and the wet lag was reduced by 38.91%and 3.62%,respectively.The unique structure of the component itself makes it more suitable for humidity detection in the high humidity range.