Specific Process Knowledge/Characterization/XPS/NexsaOverview

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Publication	'	'	'	Techniques applied	'	'	'	'	'	Sample types/Materials	Description of application/Abstract
Title	Type	Author	WOS link	XPS	UPS	ISS	REELS	Raman	Additional options/hardware
Multitechnique Surface Characterization of Organic LED Material	Application note	P Mack		X	X		X			Organic LED's	Abstract
Advantages of coincident XPS-Raman in the analysis of mineral oxides species	Application note			X				X		TiO2, CaCO3
Spectroscopic analysis of solid oxide fuel cell material with XPS	Application note	P Mack		X
Rapid XPS image acquisition using SnapMap	Application note	R Simpson		X					SnapMap
Composition, coverage and band gap analysis of ALD-grown ultra thin films	Application note	P Mack		X		X	X		Band gap	Gate dielectrics, HfO2, SiO2
Confirming the layer structure of an organic FET device	Application note	P Mack		X					MAGCIS	Organic FET's,
Surface analysis of zeolites: An XPS, variable kinetic energy XPS, and low energy ion scattering study	Publication	SR Bare	link	X		X				Zeolites, Metal oxides	<span title="The surface Si/Al ratio in a series of zeolite Y samples has been obtained using laboratory XPS, synchrotron (variable kinetic energy) XPS, and low energy ion scattering (LEIS) spectroscopy. The non-destructive depth profile obtained using variable kinetic energy XPS is compared to that from the destructive argon ion bombardment depth profile from the lab XPS instrument. All of the data indicate that the near surface region of both the ammonium form and steamed Y zeolites is strongly enriched in aluminum. It is shown that when the inelastic mean free path of the photoelectrons is taken into account the laboratory XPS of aluminosilicates zeolites does not provide a true measurement of the surface stoichiometry, while variable kinetic energy XPS results in a more surface sensitive measurement. A comprehensive Si/Al concentration profile as a function of depth is developed by combining the data from the three surface characterization techniques. The LEIS spectroscopy reveals that the topmost atomic layer is further enriched in Al compared to subsequent layers."Abstract
Surface composition analysis by low-energy ion scattering	Publication, background	H H Brongersma	link			X					Low-energy ion scattering (LEIS) is an analytical tool that provides information on the atomic composition of the outer surface, when noble gas ions are used as projectiles. In fact, quantitative composition analysis is currently done on a huge variety of materials, including catalysts and organic materials. The information on the surface composition is contained in the signal of backscattered ions (typically 1–3 keV He+, Ne+). In order to translate the LEIS signal to an elemental surface concentration all factors determining the LEIS signal must be known. These are in particular the scattering cross section and the ion fraction of the backscattered particles. The scattering cross section, which is due to the screened electrostatic potential between target atom and projectile, is well-known for the prevailing conditions of LEIS. It is an intriguing fact that, despite the large quantity of successful applications, the charge exchange processes in LEIS are not yet fully understood. It is e.g. not known why in LEIS for a given atomic species on the surface the signal usually does not depend on which other species are present (absence of matrix effects). Significant progress has recently been made in the understanding of the underlying charge exchange processes. Therefore, the aim of this review is twofold: on the one hand, to summarize the present understanding of the factors that determine the ion fraction of the scattered projectiles in LEIS, i.e. charge exchange processes. On the other hand, to summarize how quantitative surface composition analysis can be accomplished. In addition, we critically review publications that deal with surface composition analysis by LEIS, and analyze in which cases and by what means this was achieved and where and why it was successful or failed. After reading this review the reader will be able to deal with the pitfalls encountered in LEIS and to choose preferred experimental conditions for quantitative surface composition analysis.
Monitoring surface metal oxide catalytic active sites with Raman spectroscopy	Publication, review	I E Wachs	link					X		Metal oxides	The molecular aspect of the Raman vibrational selection rules allows for the molecular structural and reactivity determinations of metal oxide catalytic active sites in all types of oxide catalyst systems (supported metal oxides, zeolites, layered hydroxides, polyoxometalates (POMs), bulk pure metal oxides, bulk mixed oxides and mixed oxide solid solutions). The molecular structural and reactivity determinations of metal oxide catalytic active sites are greatly facilitated by the use of isotopically labeled molecules. The ability of Raman spectroscopy to (1) operate in all phases (liquid, solid, gas and their mixtures), (2) operate over a very wide temperature (273 degC to >1000 degC) and pressure (UHV to c100 atm) range, and (3) provide molecular level information about metal oxides makes Raman spectroscopy the most informative characterization technique for understanding the molecular structure and surface chemistry of the catalytic active sites present in metal oxide heterogeneous catalysts. The recent use of hyphenated Raman spectroscopy instrumentation (e.g., Raman–IR, Raman–UV-vis, Raman–EPR) and the operando Raman spectroscopy methodology (e.g., Raman–MS and Raman–GC) is allowing for the establishment of direct structure–activity/selectivity relationships that will have a significant impact on catalysis science in this decade. Consequently, this critical review will show the growth in the use of Raman spectroscopy in heterogeneous catalysis research, for metal oxides as well as metals, is poised to continue to exponentially grow in the coming years
Diffusion of In0.53Ga0.47As elements through hafnium oxide during post deposition annealing	Publication	W Cabrera	link	X		X			TEM	HfO2, InGaAs, ALD	Diffusion of indium through HfO2 after post deposition annealing in N2 or forming gas environments is observed in HfO2/In0.53Ga0.47As stacks by low energy ion scattering and X-ray photo electron spectroscopy and found to be consistent with changes in interface layer thickness observed by transmission electron microscopy. Prior to post processing, arsenic oxide is detected at the surface of atomic layer deposition-grown HfO2 and is desorbed upon annealing at 350 degree C. Reduction of the interfacial layer thickness and potential densification of HfO2, resulting from indium diffusion upon annealing, is confirmed by an increase in capacitance
Low energy ion scattering (LEIS). A practical introduction to its theory, instrumentation, and applications	Publication, review	C V Cushman	link			X					Low energy ion scattering (LEIS) probes the elemental composition of the outermost atomic layer of a material and provides static depth profiles of the outer ca. 10 nm of surfaces. Its extreme surface sensitivity and quantitative nature make it a powerful tool for studying the relationships between surface chemistry and surface related phenomena such as wetting, adhesion, contamination, and thin film growth. The high depth resolution obtained in LEIS in its static and sputter depth profile modes are useful for studying the layer structures of thin films. LEIS instrumentation has improved significantly in recent years, showing dramatic increases in its sensitivity and further expanding its potential applications. In this article, we provide a practical introduction to the technique, including a discussion of the basic theory of LEIS, LEIS spectra, LEIS instrumentation, and LEIS applications, including catalysts, solid oxide fuel cells (SOFCs), and thin films in integrated circuits.
HfO2 on MoS2 by Atomic Layer Deposition: Adsorption Mechanisms and Thickness Scalability	Publication	S McDonnell	link	X		X			AFM, ALD	HfO2, MoS2	We report our investigation of the atomic layer deposition(ALD) of HfO2 on the MoS2 surface. In contrast to previous reports of conformal growth on MoS2 flakes, we find that ALD on MoS2 bulk material is not uniform. No covalent bonding between the HfO2 and MoS2 is detected. We highlight that individual precursors do not permanently adsorb on the clean MoS2 surface but that organic and solvent residues can dramatically change ALD nucleation behavior. We then posit that prior reports of conformal ALD deposition on MoS2 flakes that had been exposed to such organics and solvents likely rely on contamination-mediated nucleation. These results highlight that surface functionalization will be required before controllable and low defect density high-κ/MoS2 interfaces will be realized. The band structure of the HfO2/MoS2 system is experimentally derived with valence and conduction band offsets found to be 2.67 and 2.09 eV, respectively.
Highly Sensitive Detection of Surface and Intercalated Impurities in Graphene by LEIS	Publication	S Prusa	link			X				graphene	Low-energy ion scattering (LEIS) is known for its extreme surface sensitivity, as it yields a quantitative analysis of the outermost surface as well as highly resolved in-depth information for ultrathin surface layers. Hence, it could have been generally considered to be a suitable technique for the analysis of graphene samples. However, due to the low scattering cross section for light elements such as carbon, LEIS has not become a common technique for the characterization of graphene. In the present study we use a high-sensitivity LEIS instrument with parallel energy analysis for the characterization of CVD graphene transferred to thermal silica/silicon substrates. Thanks to its high sensitivity and the exceptional depth resolution typical of LEIS, the graphene layer closure was verified, and different kinds of contaminants were detected, quantified, and localized within the graphene structure. Utilizing the extraordinarily strong neutralization of helium by carbon atoms in graphene, LEIS experiments performed at several primary ion energies permit us to distinguish carbon in graphene from that in nongraphitic forms (e.g., the remains of a resist). Furthermore, metal impurities such as Fe, Sn, and Na located at the graphene−silica interface (intercalated) are detected, and the coverages of Fe and Sn are determined. Hence, high-resolution LEIS is capable of both checking the purity of graphene surfaces and detecting impurities incorporated into graphene layers or their interfaces. Thus, it is a suitable method for monitoring the quality of the whole fabrication process of graphene, including its transfer on various substrates.
Reflection electron energy loss spectroscopy for ultrathin gate oxide materials	Publication	H C Shin	[1]	X			X		Valence band	HfZrO4,	The band alignment of HfZrO4 gate oxide thin films on Si (100) deposited by the atomic layer deposition method has been investigated using reflection electron energy loss spectroscopy and XPS. The band gap of HfZrO4 gate oxide thin film is 5.40 +/-0.05 eV. The valence band offset (ΔEv) and the conduction band offset (ΔEc) are 2.50+/-0.05 eV and 1.78+/-0.05 eV, respectively. These values satisfy the minimum requirement for the hole and electron barrier heights of larger than 1 eV for device applications. We have demonstrated that the quantitative analysis of reflection electron energy loss spectroscopy spectra obtained from HfZrO4 thin films provides us a straightforward way to determine the optical properties and the inelastic mean free path of ultrathin gate oxide materials.
Oxygen accumulation on metal surfaces investigated by XPS, AES and LEIS, an issue for sputter depth profiling under UHV conditions	Publication	R Steinberger	link	X		X			AES, ARXPS, sputter profiles	Oxygen on metal surfaces	Depth profiling using surface sensitive analysis methods in combination with sputter ion etching is a common procedure for thorough material investigations, where clean surfaces free of any contaminationare essential. Hence, surface analytic studies are mostly performed under ultra-high vacuum (UHV) conditions, but the cleanness of such UHV environments is usually overrated. Consequently, the current study highlights the in principle known impact of the residual gas on metal surfaces (Fe, Mg, Al, Cr and Zn) for various surface analytics methods, like X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and low-energy ion scattering (LEIS). The investigations with modern, stateof-the-art equipment showed different behaviors for the metal surfaces in UHV during acquisition: (i) no impact for Zn, even after long time, (ii) solely adsorption of oxygen for Fe, slight and slow changes for Cr and (iii) adsorption accompanied by oxide formation for Al and Mg. The efficiency of different counter measures was tested and the acquired knowledge was finally used for ZnMgAl coated steel to obtain accurate depth profiles, which exhibited before serious artifacts when data acquisition was performed in an inconsiderate way.
Electrochemical Characterization and Quantified Surface Termination Obtained by Low Energy Ion Scattering and X-ray Photoelectron Spectroscopy of Orthorhombic and Rhombohedral LaMnO3 Powders	Publication	E Symianakis		X		X			XRD	Catalysts, LaMnO3	LaMnO3 powder synthesized by glycine combustion synthesis with the rhombohedral and orthorhombic structures has been characterized by the combination of low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS), while the electrocatalytic activity for the oxygen reduction reaction is measured with the rotating disk electrode (RDE) method. Quantification of the surface terminations obtained by LEIS suggests that the orthorhombic LaMnO3 crystallites are near thermodynamic equilibrium as surface atomic ratios compare well with those of equilibrium morphologies computed by a Wulff construction based on computed surface energies. Both rhombohedral and orthorhombic structures present the same La/Mn atomic ratio on the surface. Electrochemical activity of the two structures is found to be the same within the error bar of our measurements. This result is in disagreement with results previously reported on the activity of the two structures obtained by the coprecipitation method [Suntivich et al. Nat. Chem. 2011, 3 (7), 546], and it indicates that the preparation method and the resulting surface termination might play a crucial role for the activity of perovskite catalysts.
The Thermal Oxidation of TiAlN High Power Pulsed Magnetron Sputtering Hard Coatings as Revealed by Combined Ion and Electron Spectroscopy	Publication	M Wiesing	link	X	X	X			Ar sputtering	TiAlN	The thermal oxidation of TiAlN hard coatings deposited by High Power Pulsed Magnetron Sputtering (HPPMS) is investigated at room temperature and 800 K at oxygen pressures ranging from 10−6 to 10−2 Pa by means of in situ X-ray and Ultraviolet Photoelectron Spectroscopy as well as Low Energy Ion Scattering. The spectra reveal that oxygen binds selectively to titanium during the initial chemisorption step and simultaneously some oxygen is dissolved into subsurface layers, which stay metallic. Enhanced oxidation results into continuous formation of a multilayered oxide film including oxynitride TiAl(O,N) as a metastable reaction product buried below an oxidic top layer. This top layer is either composed of mixed TiAlO after oxidation at 800 K or of segregated TiO2 and Al2O3 when oxidizing at 293 K. Additionally, evaluation of UV-valence bands reveals nitrogen doping of the surface oxide films. The results are of high relevance for tailoring of the surface characteristics of TiAlN after deposition, for the design of TiAlN multilayers and for an improved understanding of the interactions of gas particles with these coatings.
Electronic structure and energy band gap of poly(9,9-dioctylfluorene) investigated by photoelectron spectroscopy	Publication	L S Liao	link	X	X					Polymer	The electronic structure of poly(9,9-dioctylfluorene) PFO!film on a Au-coated Si substrate was investigated by ultraviolet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). From the UPS measurement, we obtained the ionization potential (Ip) of the PFO film, Ip =55.60 +/-0.05 eV. From the XPS shake-up peaks of the C1score level, we estimated the electron energy band gap (Eg) of the film, Eg = 53.10 +/-0.10 eV. By comparing the Eg with the optical absorption gap, we found that the value of Eg is closer to the optical absorption maximum than to the optical absorption edge. Therefore, we suggest that the optical absorption maximum may be a better approximation than the optical absorption edge in estimating Eg
Electronic and optical properties of hafnium indium zinc oxide thin film by XPS and REELS	Publication	Y R Denny	link	X			X				The electronic and optical properties of GaInZnO (GIZO), HfInZnO (HIZO) and InZnO (IZO) thin films on glass substrates were investigated using X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). XPS results show that HIZO, GIZO, and IZO thin films have mixed metal and oxide phases. REELS spectra reveal that the band gaps of GIZO, HIZO, and IZO thin films are 3.1 eV, 3.5 eV, and 3.0 eV, respectively. These band gaps are consistent with optical band gaps determined by UV-Spectrometer. The optical properties represented by the dielectric function ε, the refractive index n, the extinction coefficient k, and the transmission coefficient T of the GIZO, HIZO and IZO thin films were determined from a quantitative analysis of REELS spectra. The transmission coefficient was increased by 4% for the HIZO compound incorporating Hf into IZO, but decreased by 3% for the GIZO compound incorporating Ga into IZO in the visible region in comparison to that of IZO.