Preparation Of TiO₂/Au/TiO₂ Composite Structure And Its Photodetective Characteristics

Semiconductor photodetectors have drawn greater attention in recent years.There are a lot of application in military,environmental protection,space industry and other industries.There are some well-studied semiconductor materials like Si,SiC,GaN,ZnO etc.They have been well applied in ultraviolet photodetector.But there are some disadvantages such as their narrow bandgap and low UV selectivity.They also need optical filter.Therefore,there are some limitations of the application of these materials.Because of the wide bandgap and good chemical stability,TiO₂ has caused a lot of attention.However,there is still a question that is the compatibility of responsivity and response speed.This paper proposes that making 1D TiO₂ nanorod array by hydrothermal method,then optimizing it with noble metal nanoparticles.The metal and TiO₂ forms a built-in electric field.This field can make sure getting high responsivity and rapid response speed.And it can also offer power for the UV photodetector without the extra pressure.The detailed design idea is as follows: at first,synthesizing 1D TiO₂ nanorod array using hydrothermal method;then depositing noble metal like Au,Ag onto 1D TiO₂ nanorod array by photo deposition method;finally,modifying it with TiO₂ nanoparticles to enlarge the contact area between TiO₂ and metal to get a stronger Schottky impact.The composite structure promote the photoelectron-hole separation.The responsivities of TiO₂/metal/TiO₂ composite structure photodetector are greater than 1 A·W-1.And their response times reduce to 1s.Not only that,The responsivities,response times and sensitivities of TiO₂/metal/TiO₂ composite structure modified by TiO₂ nanoparticles are greatly improved.The biggest responsivity can reach 38.50 A·W-1,and the response times are 0.43 s ? 2.2s.Compared to the structure without TiO₂ nanoparticles,the responsivity of the structure modified by TiO₂ nanoparticles is increased by one order of magnitude.The maximum responsivity of TiO₂/Ag/TiO₂ composite structure photodetector is 11.06 A·W-1,that is enhanced by two order of magnitudes.What's more,the response time of the composite structure is only 0.05 s that is only the eighth of response time of TiO₂/Au/TiO₂ composite structure photodetector.It follows that TiO₂/metal/TiO₂ composite structure photodetector is a new self-powered ultraviolet photodetector that can get both high responsivity and rapid response speed.