Structure and electrical characteristics of bottom-up BaTiO3 films on Si

Abstract

BaTiO3 films were fabricated on Si by using Ba-Ti double alkoxide solutions. The crystallinity and crystallographic orientation were controlled by inserting LaNiO3 and Pt layers between the ferroelectric and substrates. The microstructure depended on the concentration of the precursor solutions and the thickness of single deposition layer. The phase transition was electrically investigated in (100) oriented BaTiO3 thin and thick films. Changes of the dielectric constant as a function of temperature in the range of ¿200°C to 200°C indicate that the transition from paraelectric to ferroelectric phase takes place around at 100°C instead of 130°C for single crystals. The broad peak of the dielectric constant shifted to lower temperatures and the behavior was associated with the crystallinity, orientation degree and microstructure of the films. A highly (100)-oriented columnar BaTiO3 thin film with thickness of 280 nm exhibited two transitions at 0°C and 100°C due to orthorhombic to tetragonal and tetragonal to cubic, respectively. While the 1¿m-thick BaTiO3 film with a combined structure consisted of columnar and granular grains showed a transition at 105°C. PFM measurements at room temperature revealed that the bottom-up BaTiO3 films were ferroelectric and the thinner films with thickness less than 280 nm were significantly stressed. Finally, the potential application to the micro-electromechanical system will be hopefully presented.