| Abstract: | A novel technique is introduced for probing charging/discharging dynamics of dielectric materials in which X-ray photoemission data is recorded while the sample rod is subjected to +/-10.0 V square-wave pulses with varying frequencies in the range of 10(-3) to 10(3) Hz. For a clean silicon sample, the Si2p(Si(0)) peak appears at correspondingly -10.0 eV and +10.0 eV binding energy positions (20.0 eV difference) with no frequency dependence. However, the corresponding peak of the oxide (Si(4+)) appears with less than 20.0 eV difference and exhibits a strong frequency dependence due to charging of the oxide layer, which is faithfully reproduced by a theoretical model. In the simplest application of this technique, we show that the two O1s components can be assigned to SiO(x) and TiO(y) moeties by correlating their dynamical shifts to those of the Si2p and Ti2p peaks in a composite sample. Our pulsing technique turns the powerful X-ray photoemission into an even more powerful impedance spectrometer with an added advantage of chemical resolution and specificity. |
