Browsing by Subject "External biasing"
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Item Open Access Enhanced peak separation in XPS with external biasing(Elsevier, 2005-08-15) Ertas, G.; Demirok, U. K.; Süzer, ŞefikWe have demonstrated that the An 4f peaks of the capped gold nanoparticles deposited on a SiO2 (20 nm)/Si substrate can be separated form the An 4f peaks of a gold metal strip, in contact with the same sample, by application of an external voltage bias to the sample rod while recording the XPS spectra. The external bias controls the flow of low-energy electrons falling on to the sample which in-turn controls the extent of the differential charging of the oxide layer leading to shifts in the binding energy of the gold nanoparticles in contact with the layer. The method is simple and effective for enhancing peak separation and identification of hetero-structures. (c) 2004 Elsevier B.V. All rights reserved.Item Open Access XPS analysis with external bias: a simple method for probing differential charging(John Wiley & Sons Ltd., 2004) Ertas, G.; Süzer, ŞefikThe XPS spectra of thermally grown oxide layers on Si, Al, W and Hf substrates have been recorded while the samples were subjected to external d.c. voltage bias. The bias induces additional shifts in the measured binding energy differences between the XPS peaks of the oxide and that of the metal substrate in Si and Al (as probed both in the 2p and the KLL Auger regions), but not in W and Hf (as probed in the 4f region). These bias induced shifts are attributed to differential charging between the oxide layer and the substrate, which in turn is postulated to be related to the capacitance and inversely to the dielectric constant of the oxide layer. Accordingly, silicon dioxide with the smallest dielectric constant undergoes the largest differential charging, aluminium oxide is in the middle and no appreciable charging can be induced in the high-k tungsten and hafnium oxides, all of which are ∼6 nm thick. Copyright © 2004 John Wiley & Sons, Ltd.