Study On Dielectric Properties Of Donor-acceptor Doped TiO₂ Films

The development of high-energy storage devices and highly integrated electronic components puts forward higher requirements for electronic device materials,and high-dielectric constant oxides have become an indispensable part of modern microelectronic devices.Therefore,there is a need for electronic materials with excellent dielectric properties and miniature size.TiO₂ has attracted much attention in microelectronic integration and high-frequency capacitors.In this paper,the preparation parameters and photoelectric properties of TiO₂ films were explored.By adjusting the PLD parameters,high-quality TiO₂ nano-films were prepared on the STO substrate.Studies have found that oxygen pressure annealing can increase the crystallinity of the TiO₂ film by extending the holding time,and the surface roughness will increase;while the dynamic annealing prolongs the holding time,the crystallinity of the TiO₂ film will decrease,and the film surface will remain flat.The increase in the deposition temperature promotes the crystallization of the TiO₂ film,and the crystallinity and surface morphology of the TiO₂ film are the best in the range of 600-700? at 650?.The crystallinity of the TiO₂ film prepared under high oxygen pressure annealing is better than that of dynamic annealing,and the surface roughness of the film will increase.The crystallinity of the film is higher when the oxygen partial pressure is 0.1 Pa,1 Pa,10 Pa.A TiO₂ film with a(Nb+In)doping concentration of 3-20 at%was prepared on the STO substrate,and the lattice constant c is proportional to the doping concentration.DFT calculation was used to simulate the reduction of band gap and the increase of absorption rate after TiO₂ doping;the absorption rate test results of TiO₂ film under different preparation processes showed that doping would reduce the band gap and increase the absorption rate of visible light.The absorption rate is mainly controlled by the energy band gap.The surface roughness,grain size,oxygen vacancy and other film defects of the TiO₂ film will also affect the visible light absorption rate of the TiO₂film.The optimized process parameters were used to grow a TiO₂ film on a conductive substrate.(Nb+In)doping increases the dielectric constant of the amorphous film on the Pt substrate by an order of magnitude(10³),and the dielectric loss continues to decrease.The defect complex formed after doping can restrain free electrons,which leads to the improvement of the dielectric properties.The dielectric constant of the TiO₂ film(Nb+In)doped on the Nb-doped STO is significantly improved.When the frequency is lower,and the dielectric constant decreases and stabilizes after the frequency increases.The dielectric loss has the same changing trend.