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Quantitative Biaxial Texture Analysis with Reflection High-Energy Electron Diffraction for Ion Beam-Assisted Deposition of MgO and Heteroepitaxy of Perovskite Ferroelectrics


Brewer, Rhett Ty (2004) Quantitative Biaxial Texture Analysis with Reflection High-Energy Electron Diffraction for Ion Beam-Assisted Deposition of MgO and Heteroepitaxy of Perovskite Ferroelectrics. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/J5PY-RS79.


To facilitate ferroelectric-based actuator integration with silicon electronics fabrication technology, we have developed a route to produce biaxially textured ferroelectrics on amorphous layers by using biaxially textured MgO templates.

Using a kinematical electron scattering model, we show that the RHEED pattern from a biaxially textured polycrystalline film can be calculated from an analytic solution to the electron scattering probability. We found that diffraction spot shapes are sensitive to out-of-plane orientation distributions and in-plane RHEED rocking curves are sensitive to the in-plane orientation distribution. Using information from the simulation, a RHEED-based experimental technique was developed for in situ measurement of MgO biaxial texture. The accuracy of this technique was confirmed by comparing RHEED measurements of in-plane and out-of-plane orientation distribution with synchrotron x-ray rocking curve measurements.

Biaxially textured MgO was grown on amorphous Si3N4 by ion beam-assisted deposition (IBAD). MgO was e-beam evaporated onto the amorphous substrate with a simultaneous 750-1200 eV Ar⁺ ion bombardment at 45° from normal incidence. We observed a previously unseen, dramatic texture evolution in IBAD MgO using transmission electron microscopy (TEM) and RHEED-based quantitative texture measurements of MgO. The first layers of IBAD MgO are diffraction amorphous until the film is about 3.5 nm thick. During the next 1 nm of additional growth, we observed rapid biaxial texture evolution. RHEED and TEM studies indicate that biaxially textured MgO film results from a solid phase crystallization of biaxially textured MgO crystals in an amorphous matrix.

Biaxially textured perovskite ferroelectrics were grown on biaxially textured MgO templates using sol-gel, metallorganic chemical vapor deposition (MOCVD), and molecular beam epitaxy (MBE). Through RHEED-based biaxial texture analysis we observed that the heteroepitaxial ferroelectric in-plane orientation distribution, deposited using ex situ techniques (not performed in the same high vacuum growth environment where the MgO was deposited), narrowed significantly with respect to the in-plane orientation distribution of its MgO template (from 11° to 6° FWHM). Evidence from cross section TEM and RHEED suggest that atmospheric moisture degrades the crystallinity of highly defective, misaligned MgO grains and that heteroepitaxially grown ferroelectrics preferentially nucleate on well-aligned grains and over grow misaligned regions of MgO.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:biaxial texture; ferroelectric; IBAD; ion beam-assisted deposition; MgO; RHEED
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Atwater, Harry Albert
Thesis Committee:
  • Atwater, Harry Albert (chair)
  • Bhattacharya, Kaushik
  • Davis, Mark E.
  • Haile, Sossina M.
Defense Date:10 July 2003
Non-Caltech Author Email:rhett (AT)
Record Number:CaltechETD:etd-08182003-150957
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3160
Deposited By: Imported from ETD-db
Deposited On:21 Aug 2003
Last Modified:08 Nov 2023 00:12

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