Dielectric Properties of BaTiO3 Films Prepared by RF-Plasma Chemical Vapor Deposition

Abstract

The size dependence of the dielectric properties of BaTiO3 nano-grains was investigated using films prepared by RF-plasma chemical vapor deposition. BaTiO3 nanoparticles were directly deposited on Pt/Al2O3/SiO2/Si substrates; then they were annealed at temperatures between 600 and 900°C in order to control the grain size. The dielectric constants of BaTiO3 nano-grains smaller than 30 nm were measured to be 200–300, and reached approximately 1000 for grain sizes of 50–60 nm. According to capacitance–voltage (C–V) curves and hysteresis loops, the phase transformation from paraelectric to ferroelectric occurred at a grain size of approximately 40 nm. The dielectric constants of the films were considerably stable against the temperatures ranging from 5 to 160°C, even though the dielectric constants were approximately 1000. The breakdown electric fields of the films increased with decreasing grain sizes and a value of 649 kV/cm was achieved at a grain size of 27 nm.