Charge transport and trapping in BaTiO3 thin films flash evaporated on Si and SiO2/Si

Avila R.E.; Caballero J.V.; Fuenzalida, V.M.; Eisele I.

Keywords: films, electron, transport, silicon, extinction, bias, structure, barium, stress, silica, voltage, capacitance, injection, index, curve, band, vacuum, thin, evaporation, traps, charge, shifts, coefficient, properties, annealing, flash, permittivity, effect, potential, Electric, High, titanate, Refractive, Schottky, Ultra


BaTiO3 (BT) thin films were prepared by flash evaporation onto p-Si and SiO2/p-Si from a Re boat at 1800°C in ultra high vacuum. The films are amorphous and remain so after a thickness reduction by 10-20% upon annealing at 500°C for 3 min in O2 atmosphere. Annealing raises, also, the index of refraction by some 5% and the extinction coefficient by a factor of 2. Electron injection at the Al to BT interface of Al/BT/Si capacitors is enhanced by the Schottky effect, yielding a value of 11.2 for the dielectric constant of BT. Modeling current-time measurements yields a trap density of 1024 m-3, 0.82 eV below the conduction band. Capacitance-voltage curve shifts due to bias stress on Al/BT/SiO2Si capacitors are interpreted as caused by electron injection and trapping in the BT films. Starting deposition at 170°C or post-deposition annealing reduces the trap density and increases the capacitance-voltage curve shifts by bias stress, from 0.3 to over 14 V at bias stress of - 10 V.

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Título de la Revista: THIN SOLID FILMS
Volumen: 348
Número: 1
Editorial: Elsevier
Fecha de publicación: 1999
Página de inicio: 44
Página final: 48