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Measurements of ion‐induced ferroelectric emission and surface charge dynamics on LiTaO3(0001) by time‐of‐flight scattering and recoiling spectrometry (TOF‐SARS)

We have derived a special surface analysis method for studying surface charge dynamics on ferroelectrics from time‐of‐flight ion scattering and recoiling spectrometry (TOF‐SARS). In this method, shifts of the TOF‐SARS peaks of a ferroelectric crystal are measured as a function of sample temperature, and these spectral data are used to deduce changes in electrical potential on the sample surface. These changes are then converted to information on surface charge dynamics. In addition, the method is also applicable in extracting data regarding ion‐induced ferroelectric electron emission (FEE) from the TOF‐SARS spectra. In this work, we have tested the method with LiTaO3(0001) crystals having the nominal stoichiometry and single domain properties. Our results show that for temperature changes from 25 to ∼100 °C, the excess amount of surface charge induced by pyroelectricity, ion irradiation, and ion‐induced electron emission is drained mainly by surface conductivity. For temperature changes above 100 °C, the bulk ionic conductivity becomes an important charge drainage channel. Our measurements give an activation energy of 0.75 eV for the thermally activated ionic conductivity, and the result agrees well with the literature value previously obtained by d.c. conductivity measurements. Copyright © 2006 John Wiley & Sons, Ltd.