Effects of crystallization on structural and dielectric properties of thin amorphous films of (1−x)BaTiO3-xSrTiO3 (x=0–0.5, 1.0)

Abstract

The possibilities for fabricating solid solutions of (Ba1−x,Srx)TiO3 (x≤0.5,1.0) by crystallization of amorphous films and for improving their dielectric properties by adjusting the Sr content were investigated. Thin amorphous films were prepared from powder targets consisting of mixtures of BaTiO3 and SrTiO3 by sputtering with a neutralized Ar-ion beam. The amorphous films crystallized into (Ba1−x, Srx)TiO3 solid solutions with a cubic perovskite-type structure after annealing in air at 923 K for more than 1 h. The Debye-type dielectric relaxation was observed for the amorphous films, whereas the crystallized films showed paraelectric behavior. The relative dielectric constants were of the order of 20 for the amorphous samples, but increased greatly after crystallization to about 60–200, depending on the composition; a larger increase in the dielectric constant was observed in the higher Sr content films, in the range x≤0.5, which could be correlated with an increase in the grain size of the crystallites. The crystallization processes responsible for the difference in the grain size are discussed based on the microstructural observations.

Formation and thermal stability of quasi-amorphous thin films

“…1,2,12,[14][15][16][17][18][19] Nucleation begins within the temperature range of 470-500°C. 1,15 However, films crystallized below 700°C may have a low density due to high porosity and a noticeable dilatation of the lattice.…”

Photocatalytic property of a keggin-type polyoxometalates-containing bilayer system for degradation organic dye model

“…Preparation of POM-containing films is a new method to immobilize soluble POM [18][19][20][21][22][23][24]. Several good techniques of preparation of composite films have included: Langmuir-Blodgett (LB) deposition [25], casting or spin-coating [26,27], electrochemistry [28], sol-gel technique [29], sputtering [30], vacuum evaporation [31], and (LbL) self-assembly method [32][33][34][35]. Among all the techniques mentioned above, LbL self-assembly method is based on the sequential adsorption of oppositely charged species from dilute solutions and has been commonly applied to multilayer assemblies of organic polymers [36][37][38].…”

Bi1-x-yTixSiyOz (BTSO) Thin Films for Dynamic Random Access Memory Capacitor Applications

“…The term t ox represents the theoretical thickness of SiO 2 that would be required to achieve the same capacitance density obtained from a high-k dielectric capacitor. It should be noted that the amorphous BST or ST (SrTiO 3 ) films usually show a similar dielectric constant (~20) [18] with low leakage current density. However, with post-annealing, these amorphous film easily crystallized to a polycrystalline film with large grain sizes and many pores that result in a large leakage current.…”