Volume 21, Issue 1, December 2014
Index of content:
21(2014); http://dx.doi.org/10.1116/11.20140101View Description Hide Description
β-Fe2O3-CuO nanosystems were developed by using a two-step vapor-phase strategy. β-Fe2O3 matrices (hosts) were initially deposited by Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) on Indium Tin Oxide (ITO) substrates. Subsequently, CuO nanoparticles (NPs, guests) were over-deposited by means of Radio Frequency (RF)-sputtering under mild preparation conditions. A thorough characterization highlighted the dispersion of CuO NPs inside the host iron oxide. To this regard, X-ray Photoelectron and X-ray Excited Auger Electron Spectroscopies (XPS and XE-AES) analyses provided valuable information on the system chemical composition. In particular, attention has been devoted to the analysis of the O 1s, Fe 2p, Cu 2p core levels and Cu LMM Auger peak, employing a non-monochromated MgKα source. The investigation confirmed the presence of Fe(III) and Cu(II) oxides, highlighting the formation of nanocomposites in which the host and guest species maintained their chemical identity.
21(2014); http://dx.doi.org/10.1116/11.20130902View Description Hide Description
In this investigation, thermal vapor deposition was used to synthesize films of polyvinylidene fluoride (PVDF) containing nanoparticles of the ceramic titanium dioxide (TiO2). This ferroelectric polymer has shown promise as a capacitor dielectric material with possible enhanced electrical properties when combined with ceramic nanoparticles. The films were synthesized starting from a mixture of PVDF and TiO2 (rutile phase) dissolved in dimethylformamide (DMF) solvent. The PVDF-TiO2 mixture was vapor deposited onto a Si wafer. The temperature during the deposition was approximately 400 °C and the deposition time was 15 min. The deposited films were characterized using x-ray photoelectron spectroscopy (XPS). It is noted that various starting mixtures and deposition parameters were investigated. The spectra reported here are from films from two different initial PVDF/TiO2 mixtures (prior to deposition). For the maximum concentration of TiO2 in the deposited films, the Ti atomic concentration is just under 10%. Analysis from XPS shows a defluorination of the films (C/F ratio >1) from the deposition process, with the final film being a mixture of PVDF and polyvinyl fluoride (PVF). It is also noted that energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM) show that the TiO2 nanoparticles are homogeneously distributed in the films. The reported XPS spectra include survey and high resolution scans of the major photoelectron peaks.
21(2014); http://dx.doi.org/10.1116/11.20140401View Description Hide Description
Molybdenum disulfide (MoS2), a two-dimensional material purchased from SPI supplies, was analyzed using high-resolution X-ray photoelectron spectroscopy (XPS). A flake was mechanically exfoliated from a MoS2 bulk single crystal for the study. The XPS spectra of MoS2 obtained using monochromatic Al K α radiation at 0.83401 nm include a survey scan, high-resolution spectra of O 1s, Mo 3p, C 1s, Mo 3d, S 2s, S 2p, Mo 4s, Mo 4p, S 3s, and valance band. Extended energy ranges were collected in the vicinity of the Mo 3d/S 2s, S 2p, and Mo 4s/Mo 4p/S 3s/Valence band regions allowing for fitting of surface plasmon features and determination of Tougaard scattering cross-section parameters. Quantitative analysis indicates a surface composition of MoS1.9.
21(2014); http://dx.doi.org/10.1116/11.20140301View Description Hide Description
We report the characterization of a thin film of propylene carbonate acquired at −120 °C deposited onto an aluminum substrate using a cold stage. Reference spectra for propylene carbonate were acquired using monochromatic Al K α radiation. An XPS survey scan, a C 1s narrow scan, an O 1s narrow scan, an O KLL Auger narrow scan, an O 2s narrow scan and a valence band narrow scan were collected.
X-ray Photoelectron Spectroscopy Analyses of the Electronic Structure of Polycrystalline Ti1-xAlxN Thin Films with 0 ≤ x ≤ 0.9621(2014); http://dx.doi.org/10.1116/11.20140506View Description Hide Description
Metastable Ti1-x Al xN (0 ≤ x ≤ 0.96) alloy thin films are grown by reactive magnetron sputter deposition using a combination of high-power pulsed magnetron (HIPIMS) and DC magnetron sputtering (DCMS). Layers are deposited from elemental Ti and Al targets onto Si(001) substrates at 500 °C. All Ti1-x Al xN film surfaces are analyzed by x-ray photoelectron spectroscopy (XPS) employing monochromatic Al K α radiation (hν = 1486.6 eV). Prior to spectra acquisition, TiAlN surfaces are sputter-cleaned in-situ with 4 keV Ar+ ions incident at an angle of 70° with respect to the surface normal. XPS results reveal satellite structures on the high binding energy side of the Ti 2p, Ti 3s, and Ti 3p core-level signals. The intensities of the primary Ti features (Ti 2p, Ti 3s, and Ti 3p) decrease with increasing AlN concentration such that the satellite peaks dominate spectra from films with x ≥ 0.67. The density-of-states at the Fermi level also decrease with increasing x indicating that the satellite peaks are due to screening of core holes created by the photoionization event. Film compositions, obtained using XPS sensitivity factors, agree to within ±3% with values determined by time-of-flight elastic recoil detection analyses.
Comparison of Ar+ Monoatomic and Cluster Ion Sputtering of Ta2O5 at Different Ion Energies, by XPS: Part 1 - Monoatomic Ions21(2014); http://dx.doi.org/10.1116/11.20140701View Description Hide Description
A standard 30 nm thick Ta 2O5 oxide layer grown on Ta was examined by XPS after Ar+ ion bombardment at ion energies of 200 eV, 500 eV, and 3 keV. The reduction of Ta 2O5, resulting from the preferential sputtering of oxygen after ion beam bombardment at different energies has been investigated. Survey spectra, C 1s, Ta 4f and O 1s spectra are presented for each profile at three stages: native surface, after reaching the steady-state oxide composition, and from the underlying metal substrate. Reducing the Ar+ energy from 3 keV to 200 eV makes no substantial difference in the degree of Ta 2O5 reduction observed following ion bombardment.
Comparison of Ar+ Monoatomic and Cluster Ion Sputtering of Ta2O5 at Different Ion Energies, by XPS: Part 2 - Cluster Ions21(2014); http://dx.doi.org/10.1116/11.20140702View Description Hide Description
A standard 30 nm thick Ta 2O5 oxide layer grown on Ta was examined by XPS after Arn + cluster ion bombardment at ion energies of 4 keV, 5 keV and 6 keV, with a cluster size of 1000 atoms. The reduction of Ta 2O5, resulting from the preferential sputtering of oxygen after ion beam bombardment at different energies has been investigated. Survey spectra, C 1s, Ta 4f and O 1s spectra are presented for each profile at three stages: native surface, after reaching the steady-state oxide composition, and from the underlying metal substrate. It is necessary to reach a voltage of 6 keV to obtain a good sputter rate. The use of the cluster source seems to be promising to reduce the preferential sputtering phenomenon.