Preparation And Properties Of Bi₄Ti₃O₁₂ Thin Films For FFET

Due to the advantage of non-destruction read out, Ferroelectric Field Effect Transistor (FFET) is supposed to be the ideal potential memory device and has been widely investigated. But its high leakage current and poor retention is the main obstacle to its application. Improving the quality of ferroelectric thin films and avoiding the reaction and diffusion between F-S interfaces is one of the crucial keys to overcome this problem. That is to say that the preparation and properties of ferroelectric thin films is compatible with the semiconductor integrated circuit. In this thesis, we present a systematically investigation of preparation and properties of Bi4Ti3O12 thin films. The main contents are as follows:Bismuth nitrate and titanium(IV) isopropoxide are used as start materials. Bismuth nitrate is dissolved in 2-methoxyethanol to form bismuth solution, while titanium(IV) isopropoxide is stabilized by acetylacetone to form titanium solution. An excess of 10% Bi was used to compensate evaporation of bismuth during annealing. Bi/4Ti3O12 precursor solution is obtained by mixing the two solutions. The precursor is stable.Bi4Ti3O12 thin films are coated on p-Si wafers by sol-gel method and annealed at high temperature. The effects of annealing process especially the temperature on crystallization and surface microstructure of ferroelectric thin films are investigated by the method of XRD and SEM. It is helpful to choice the good parameters of preparing the randomly-oriented and compact Bi4Ti3O12 thin films. There is no crack and pole on the films.The hysteresis loops, I-V characteristics and C-V characteristics of ferroelectric thin films are studied. A conclusion can be drawn that the films have good ferroelectrical properties by annealing at 650-700 for 30 Min. and 62 ambienance.Finally, ferroelectric thin films of good microstructure and ferroelectrical properties can been achieved by appropriate parameters of preparation and annealing process.