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Proceedings of the 18th European Conference on Applications of Surface and Interface Analysis (ECASIA '19), Dresden, Germany, September 15-20, 2019; International audience; Cu(In,Ga)Se2 absorbers were immerged in deionized water for different times, and specific chemical evolutions were monitored thanks to X-ray photoemission spectroscopy. Cu(In,Ga)Se2 related dissolution products were studied in water through induced coupled plasma optical emission spectroscopy. From those analyses, specific surface network disorganization was observed, with Cu migration towards the surface, leading to different kinetics of oxidation and dissolution for each element that could be quantified.

International audience; During high-electron-mobility transistor elaboration process, a thermal treatment of In0.2Al0.8N (InAlN) barrier layer is performed in order to improve electrical performances. We showed previously that In0.2Al0.8N/GaN heterostructures, annealed at 850°C under O2 partial pressure, present a specific in-depth organization. Angle-resolved X-ray photoelectron spectroscopy is a powerful tool to precisely determine the spatial localization and relative position of the different interfaces, from InAlN until buried GaN layer. The proposed in-depth model of the stack evidences (1) an Al-rich surface oxide with embedded N2 molecules, (2) an interlayer of InAlN

International audience; The preservation of bronze and copper heritage objects is challenging. Exposure to water or pollution in outdoor conditions leads to corrosion phenomena, which can highly degrade the objects or structures. We aim to develop an alternative nontoxic corrosion inhibiting treatment, based on the use of a carboxylate (HC10) treatment. Electron spectroscopies (X‐ray photoelectron spectroscopy and scanning Auger microscopy) are used to determine, from micrometric to nanometric scale, the composition and chemical environments (oxidation degrees) of the copper compounds commonly found in the corrosion product layer. In the present study, we focus on the evaluation of X‐ray beam irradiation damage when performing surface analysis on cuprite, brochantite, and Cu decanoate reference samples. The reduction phenomenon has already been reported, especially for Cu(II) compounds, but not clearly explained. Different behavior has been observed depending on the X‐ray source used, and the nature and hydration level of the compounds. The photoreduction issue is critical, as it guarantees the reliability of the chemical information obtained and sheds light on the best analysis pathway to adopt when multitechnique analyses are implemented. An analytical procedure is employed to track the reduction of Cu(II) reference samples during XPS analysis evidencing practically instantaneous modifications of the spectra and thus, the instability of these phases except for the dehydrated cuprite sample.

An innovative treatment of III-V surface is evidenced in liquid ammonia (NH3liq). This treatment is performed by a controlled anodic electrochemical process at the interface.1 This control provides a novel and reproducible passivation of the InP surface.1 The surface coating prevents the formation of oxides for over a year.1 The low anodic charge (≈1 mC.cm−2 range) spent for the process concurrently involves a weak electrochemical dissolution of InP surface and ammonia oxidation which trigger the passivation process.1 Studies using either cyclic voltammetry or galvanostatic treatment followed by XPS measurements show that the surface is successfully passivated by an ultrathin film associating phosphorus and nitrogen atoms in a quasi-monolayer structure. Reproducible XPS data indicate that the ratio between nitrogen and phosphorus atoms in the film is close to two. High resolution N1s spectra reveal a double structure of the peaks, indicating that two chemical environments must be considered to describe the nitrogen atoms neighboring in this capping film. Information about the spatial film organization are investigated by angular-resolved XPS depth profiles analysis. Experiments are performed with a Thermo Fisher Scientific Theta Probe XPS spectrometer which exhibits an innovative ARXPS acquisition mode. The evolution of the respective contributions of P and N or In signals, perpendicularly to the surface, permit to propose a paving of the surface with a polyphospazene like film. Copyright © 2010 John Wiley & Sons, Ltd.

In some cases, XPS analysis can be used to determine the reactions that take place at a solid/solution interface. In this study, the behaviour of GaAs in contact with an acidic aqueous solution containing a Keggin-type heteropolyanion—SiMo12O404−—was investigated on the basis of the XPS data. During immersion in the solution, a film composed of elemental As and partially reduced heteropolyanion develops on the GaAs surface. The chemical composition of the surface film indicates that at the GaAs/solution interface the heteropolyanion is reduced whereas GaAs undergoes an anodic dissolution process. The GaAs dissolution rate is proportional to the heteropolyanion concentration. At a given immersion time, the nature of the GaAs surface film is independent of the heteropolyanion concentration, whereas the As0/heteropolyanion ratio and the film thickness depend on this concentration. Moreover, the chemical composition of the film changes by exposure to air, as some elemental As atoms volatilize. Copyright © 2002 John Wiley & Sons, Ltd.

Quantitative XPS analysed are carried out to study the III-V semiconductor/solution interface. In the presence of ceric ions (Ce 4+ ) solvated acid (H 2 SO 4 , 0.5-2 M), III-V compounds undergo a dissolution which is completely goverged by an electrochemical process. Competition between a superficial oxide growth and its quasi-simultaneous dissolution determines the behaviour of the interface as a function of time. On Inp some typical surface evolutions are observed, such as a decrease in the hole injection current during the reduction of cerium oxidized species