Influence of stresses on the properties of ferroelectric BaTiO[sub 3] thin films

Journal Article · Fri Oct 01 00:00:00 EDT 1993 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2220943· OSTI ID:5867196

Desu, S B ^[1]

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1. Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering

Stresses in rf sputtered polycrystalline BaTiO[sub 3] thin films, deposited at 300--700 C and at pressures from 0.1 to 100 Pa, on both Si and sapphire single crystals, were investigated. From the measured total stress values at room temperature, both the intrinsic stresses in the film and biaxial modulus of the film, E[sub f]/(1[minus]v[sub f]), were calculated. At lower deposition temperatures and pressures compressive intrinsic stresses were obtained whereas, at high deposition temperatures and pressures intrinsic stresses were tensile in nature. The biaxial modulus value approached the single crystal value for films deposited at low pressures and decreased significantly with increasing deposition pressure. BaTiO[sub 3] films with high compressive stresses ([>=]400 MPa) showed higher refractive indexes, higher extinction coefficients and lower optical bandgaps compared to those for films with low compressive stresses ([approx equal]40 MPa). Furthermore, Curie point and coercive fields were increased while remanent polarization decreased with increasing compressive stress. In addition, films in a state of high compression showed a broad peak in dielectric constant vs. temperature curve which indicates a diffuse transition from ferroelectric to paraelectric state. By a judicious choice of deposition conditions, BaTiO[sub 3] films having low intrinsic stresses and properties close to those of single crystals were obtained. For example, some of the properties of BaTiO[sub 3] films deposited at 650 C and at 2 Pa pressure on silicon substrate are: n = 2.37 at 700 nm, E[sub g] = 3.13 eV, P[sub r] = 15.9 [mu]C/cm[sup 2], E[sub c] = 10.2 kV/cm, Curie point = 129 C and [sigma][sup i] = [minus]47 MPa.

• OSTI ID: 5867196
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 140:10; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
PHYSICAL PROPERTIES
STRESSES
ENERGY BEAM DEPOSITION FILMS
TITANATES
CURIE POINT
DIELECTRIC PROPERTIES
FERROELECTRIC MATERIALS
PHASE TRANSFORMATIONS
PROCESS CONTROL
REFRACTIVE INDEX
SAPPHIRE
SILICON
SPUTTERING
SUBSTRATES
ALKALINE EARTH METAL COMPOUNDS
COATINGS
CONTROL
CORUNDUM
ELECTRICAL PROPERTIES
ELEMENTS
FILMS
MINERALS
OPTICAL PROPERTIES
OXIDE MINERALS
OXYGEN COMPOUNDS
SEMIMETALS
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
360603* - Materials- Properties
360606 - Other Materials- Physical Properties- (1992-)