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Crystal quality and orientation of pulsed laser deposited barium titanate thin films


Singh, R.K.; Lowndes, D.H.; Chrisey, D.B.; Fogarassy, E.; Narayan, J.; Kawai, T. ; Materials Research Society -MRS-:
Advances in laser ablation of materials
Warrendale, PA: MRS, 1998 (Materials Research Society symposia proceedings 526)
ISBN: 1-55899-432-7
S.175-180 : Ill., Lit.
Symposium Advances in Laser Ablation of Materials <1998, San Francisco/Calif.>
Fraunhofer ILT ()
crystalline quality; film forming particle; KeF excimer laser radiation; micro raman spectroscopy; polarization versus voltage; random access memory

KrF excimer laser radiation (lambda=248 nm, tau=25 ns) is used for pulsed laser deposition of BaTiO3 thin films on Pt/Ti/Si multilayer substrates. The processing gas atmosphere consists of O2 at typical pressures of p=10 (exp -3)- 5 x 10 (exp -1) mbar. The investigations concentrate on the influence of the substrate temperature and the kinetic energy of the film forming particles on the crystalline structure and orientation of the growing films. X-ray diffraction measurements and polarization dependent micro Raman spectroscopy reveal oriented growth of the films with c-axis orientation normal to the substrate surface and (100) texture if the energy of the particles is > 60 eV, while at lower kinetic energies a (110) or (111) texture with partly a-axis orientation is preferred. The ferroelectricity and the dielectric constant of the films, as determined by polarization versus voltage (P-V) and capacitance versus voltage (C-V) impedance measurements, decreases with increasing kinetic ene rgy of the film forming particles. This decrease of the dielectric properties correlates with the change of the preferred orientation and the crystalline quality of the films.