Preparation Of BaTiO₃ On Si Substrates And Applications In MOS And Magnetoelectric Coupling Components

Barium titanate?BaTiO₃,BTO?has excellent performance in many aspects,and the BTO/Si heterojunction formed after its deposition on the Si substrate has shown great application potential in fields such as MOS transistors and solar cells.For this oxide/Si structure,the formation of a controllable and strong built-in electric field at the interface is critical.However,due to the limitation of material solubility,it is difficult to obtain carrier concentration satisfying device requirements without changing material properties by doping.Therefore,it is of great significance to explore a new method to control the generation of sufficient and controllable effective carriers that can participate in the formation of the built-in electric field in the materials.In this paper,amorphous BTO films with a specific network structure were prepared by RF magnetron sputtering at room temperature after deposition and subsequent heat treatment using p-Si?111?as the substrate.The results show that the network structure of amorphous BTO films can be adjusted by annealing:when the annealing temperature increases from as-deposited to 420?,Ti and O are continuously bonded by covalent bonds,and Ti-O network is gradually integrated,which will increase the binding energy difference between O 1s and Ti 2p from 71.53ev to 71.67eV.When the annealing temperature continues to rise,the distortion of Ti-O network decreases,and the binding energy difference between O 1s and Ti 2p begins to decrease.This different formation state of Ti-O network determines the strength of the built-in electric field at the BTO/p-Si interface:when the annealing temperature is lower than 340?,the flat band voltage of the BTO/p-Si heterojunction is only about-3V.When the annealing temperature reaches 370? and above,the flat band voltage changes dramatically,reaching about-13V.When the annealing temperature continues to rise to 500?,the flat band voltage is restored to about-3V.For crystalline BTO films annealed at 700?,the flat band voltage is only about-1V.On the other hand,BTO-NZFO composite films formed by Ni_0.5Zn_0.5Fe₂O₄?NZFO?and BTO were prepared on p-Si?111?substrate by RF magnetron sputtering.The results show that the NZFO in the films is distributed as independent particles with a particle size of about 1 m when annealed at 800?1000?,and the NZFO phases have?100?crystallographic orientation.