Preparation And TCR Properties Of Oxygen Vacancy TiO₂ Thin Films

Infrared detectors have the advantages of strong anti-interference ability,high concealment,and low price and are widely used in military,national defense,and commercial fields.As an essential member of the infrared detector family,uncooled heat detectors have evolved from simple unit components to highly integrated focal plane array devices.Currently,vanadium oxide(VO_x)and amorphous silicon(a-Si)are the most common materials for infrared thermosensitive materials,but the former can cause unnecessary phase changes at high temperatures,while the latter can produce excessively high 1/f noise during infrared detection,which limits their applications.As a new type of thermal sensitive material with high temperature coefficient of resistance(TCR),low 1/f noise parameters,and low manufacturing process cost,TiO₂ has been favored by the majority of scientific researchers and used in infrared detectors.TiO₂ is optimized by annealing heat treatment and microwave plasma etching to obtain TiO_2-xwith oxygen vacancies in this paper.The specific research process is mainly realized through the following aspects:(1)The electron beam evaporation coating method is used to prepare a dense,uniform,high crystallinity TiO₂ film on silicon dioxide(Si O₂)substrate.Subsequently,the prepared TiO₂ film was annealed in a vacuum tube furnace.A self-assembled microwave plasma etching system performs microwave plasma etching on the film to obtain the desired film sample.(2)X-ray diffraction(XRD),Raman spectroscopy(Raman),thermal field emission electron microscope(FE-SEM),and X-ray photoelectron spectroscopy(XPS)were used to characterize the morphology,structure,and composition of the prepared film.The results show that the TiO_2-x film after microwave plasma etching has a rough morphology,and the crystal phase changes from amorphous to a crystalline structure.(3)A four-probe high-temperature resistance tester was used to measure the temperature resistance of the TiO_2-x thin films etched by microwave plasma at different times under each gas composition.The results show that the resistance of the film decreases with the increase of the etching time.Through calculation and comparison,it is found that when the flow rates of argon(Ar)and hydrogen(H₂)are 90 sccm and 30sccm,respectively,and after annealing treatment and 4 minutes of microwave plasma etching treatment,TiO_2-x has the highest TCR value(1.93075-%K^-1).In summary,TiO₂ films after microwave plasma etching have higher TCR parameters and better ohmic contact characteristics due to the increase of oxygen vacancies and the change of crystal phase.It is an excellent thermal-sensitive material and has a good application prospect in uncooled thermal detectors.