AVS 52nd International Symposium
    Thin Films Monday Sessions
       Session TF-MoP

Paper TF-MoP14
Growth of Novel NaCdF@sub3@ Thin Films by Pulsed Laser Deposition for Advanced Ferroelectric Applications

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Aspects of Thin Films Poster Session
Presenter: T. Aburada, University of Virginia
Authors: T. Aburada, University of Virginia
C.T. Nelson, University of Virginia
R.W. Smith, University of Nebraska-Omaha
S.B. Qadri, US Naval Research Laboratory
J.M. Fitz-Gerald, University of Virginia
Correspondent: Click to Email
Ferroelectrics are an important class of materials in a variety of applications including, non-volatile random access memories.@footnote 1@ Recent computer simulations have predicted that NaCdF@sub 3@ has a ferroelectric ground state.@footnote 2@ Moreover, NaCdF@sub 3@ is predicted to have a large energy band gap and be transparent in the UV spectrum, thus having potential for use in electro-optic applications.@footnote 2@ Thin films of NaCdF@sub 3@ were grown by Pulsed Laser Deposition (PLD) on Si (100) substrates using a high purity NaF and CdF@sub 2@, 1:1 molar fraction, starting target in a high vacuum chamber. A KrF excimer laser (@lambda@ = 248 nm) was used to deposit films as a function of growth temperature, system pressure, and laser energy. All films exhibited a large degree of roughness along with pronounced surface irregularities, as evidenced by Scanning Electron Microscopy (SEM) images. X-ray Diffraction (XRD) data showed that the films consist of two binary phases: CdF@sub 2@ and NaF, closely matching the stoichimetries of the starting target constituents. Although XRD analysis indicates the absence of the ternary NaCdF@sub 3@ phase, it is important to point out that oxide peaks are not observed. This is a significant hurdle to overcome in producing these materials. Compositional measurements by Energy Dispersive X-ray Spectroscopy (EDXS) indicate that the atomic fraction of Na to Cd is lower in the deposited thin film than in the initial target material. A comparison of the XRD spectra of the deposited film and the target reveals a decrease in the NaF phase in the films. With the large band gap associated with NaF, KrF irradiation is not the optimum choice due to its relatively low energy of 5eV. @FootnoteText@ @footnote 1@J.S. Horwitz, K.S. Grabowski, D.B. Chrisey, R.E. Leuchtner, Appl. Phys. Lett. 59 (13), 23 (1991)@footnote 2@ C. Duan, W.N. Mei, J. Liu, W. Yin, J. R. Hardy, R.W. Smith, M.J. Mehl, L.L. Boyer, Phys. Rev. B 69, 033102 (2004).