Browsing by Subject "Auger electron spectroscopy"

Now showing 1 - 4 of 4

Open Access
Electrical properties from photoinduced charging on Cd-doped (100) surfaces of CuInSe2 epitaxial thin films
(AVS Science and Technology Society, 2016) Johnson, N.; Aydogan, P.; Süzer, Şefik; Rockett, A.
The photoresponse of Cd-doped CuInSe2 (CIS) epitaxial thin films on GaAs(100) was studied using x-ray photoelectron spectroscopy under illumination from a 532 nm laser between sample temperatures of 28-260 °C. The initial, air-exposed surface shows little to no photoresponse in the photoelectron binding energies, the Auger electron kinetic energies or peak shapes. Heating between 50 and 130 °C in the analysis chamber results in enhanced n-type doping at the surface and an increased light-induced binding energy shift, the magnitude of which persists when the samples are cooled to room temperature from 130 °C but which disappears when cooling from 260 °C. Extra negative charge trapped on the Cu and Se atoms indicates deep trap states that dissociate after cooling from 260 °C. Analysis of the Cd modified Auger parameter under illumination gives experimental verification of electron charging on Cd atoms thought to be shallow donors in CIS. The electron charging under illumination disappears at 130 °C but occurs again when the sample is cooled to room temperature.
Open Access
Electron spectroscopic investigation of Sn coatings on glasses
(Springer, 1996) Süzer, Ş.; Voscoboinikov, T.; Hallam, K. R.; Allen, G. C.
Float glasses of different thicknesses and a conducting tin oxide glass have been investigated using Photo and Auger Electron Spectroscopy induced by AlKα X-rays. On the basis of measured chemical XPS shifts in the binding energies the chemical state of Sn (+2 or +4) incorporated on the float glasses could not be assigned. The use of the Auger parameter allows to separate relaxation and chemical contributions. The derived true chemical shifts of Sn on float-glasses are larger than those of SnO and/or SnO2 due to the larger ionic environment of the glass matrix. Ar+ or HF etching reveals that the concentration of Sn decreases exponentially as a function of depth from the surface. © Springer-Verlag 1996.
Open Access
Theoretical and spectroscopic investigations on the structure and bonding in B-C-N thin films
(2009) Bengu, E.; Genisel, M. F.; Gulseren, O.; Ovali, R.
In this study, we have synthesized boron, carbon, and nitrogen containing films using RF sputter deposition. We investigated the effects of deposition parameters on the chemical environment of boron, carbon, and nitrogen atoms inside the films. Techniques used for this purpose were grazing incidence reflectance-Fourier-transform infrared spectroscopy (GIR-FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). GIR-FTIR experiments on the B-C-N films deposited indicated presence of multiple features in the 600 to 1700 cm- 1 range for the infrared (IR) spectra. Analysis of the IR spectra, XPS and the corresponding EELS data from the films has been done in a collective manner. The results from this study suggested even under nitrogen rich synthesis conditions carbon atoms in the B-C-N films prefer to be surrounded by other carbon atoms rather than boron and/or nitrogen. Furthermore, we have observed a similar behavior in the chemistry of B-C-N films deposited with increasing substrate bias conditions. In order to better understand these results, we have compared and evaluated the relative stability of various nearest-neighbor and structural configurations of carbon atoms in a single BN sheet using DFT calculations. These calculations also indicated that structures and configurations that increase the relative amount of C-C bonding with respect to B-C and/or C-N were energetically favorable than otherwise. As a conclusion, carbon tends to phase-segregate in to carbon clusters rather than displaying a homogeneous distribution for the films deposited in this study under the deposition conditions studied.
Open Access
X-ray photoelectron spectroscopic analysis of Si nanoclusters in SiO 2 matrix
(American Chemical Society, 2006) Dane, A.; Demirok, U. K.; Aydınlı, Atilla; Süzer, Şefik
We investigated silicon nanoclusters Si(nc) in a SiO2 matrix prepared by the plasma-enhanced chemical vapor deposition technique, using X-ray photoelectron spectroscopy (XPS) with external voltage stimuli in both static and pulsed modes. This method enables us to induce an additional charging shift of 0.8 eV between the Si2p peaks of the oxide and the underlying silicon, both in static and time-resolved modes, for a silicon sample containing a 6 nm oxide layer. In the case of the sample containing silicon nanoclusters, both Si2p peaks of Si(nc) and host SiO2 undergo a charging shift that is 1 order of magnitude larger (> 15 eV), with no measurable difference between them (i.e., no differential charging between the silicon nanoclusters and the oxide matrix could be detected). By use of a measured Auger parameter, we estimate the relaxation energy of the Si(nc) in the SiO2 matrix as -0.4 eV, which yields a -0.6 eV shift in the binding energy of the Si(nc) with respect to that of bulk Si in the opposite direction of the expected quantum size effect. This must be related to the residual differential charging between the silicon nanoclusters and the oxide host. Therefore, differential charging is still the biggest obstacle for extracting size-dependent binding energy shifts with XPS when one uses the oxide peak as the reference. © 2006 American Chemical Society.