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Photoemission experiments were performed on Si/MoSi2 multilayers using soft x-ray standing waves for excitation. The combination of photoemission spectroscopy and standing-wave excitation results in a depth profile of the sample that is also sensitive to chemical states. The experimental data were analyzed using an approximate analytical, rather than a full numerical, method in order to more quickly yield results, as well as to calibrate and better understand the method. The important parameters in the resulting equations are discussed in detail. Thus, we quickly obtain access to the key parameters modulating the photoelectron intensity excited by x-ray standing waves. We demonstrate the analytical approach on a simple experimental test data set.

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A chemical-specific photoelectron diffraction structure determination of a carbon rich buffer layer on SiC is reported. In addition to the long-range ripple of this surface, a local buckling in the hexagonal sublattice, which breaks the local range order symmetry, was unraveled.

Many applications in electronics and spintronics rely on interfaces, which are buried a few nanometers deep and thus hardly accessible in real devices except for invasive techniques. Here, we report on hard x-ray photoemission spectroscopy combined with the x-ray standing-wave technique as a non-invasive method to access buried interfaces with a depth resolution of a fewÅ and enhanced interface sensitivity. Within these experiments, the film thicknesses and also the thicknesses of the intermixing layers are determined. We extend the data analysis scheme previously developed for soft x-rays to the hard x-ray regime and apply the method to buried epitaxial Fe/MgO interfaces, which play a crucial role in magnetic tunnel junctions and their applications. It was found that there was no detectable intermixing of reaction of the Fe and MgO layers at the interface.

We report a combined high-resolution photoemission (XPS) and photoelectron diffraction (XPD) investigation of the three layer system MgO/Fe/GaAs(001). Each layer is investigated with regard to its structure. The two dimers model of the GaAs (4 × 2) reconstruction was confirmed by XPD patterns. We find the intermediate Fe layer in a crystalline structure. Further, the study clearly shows a well-ordered epitaxial MgO film on Fe. A careful analysis of the interface signals indicates an interdiffusion at the Fe/GaAs interface and partially shifted magnesium layers at the MgO/Fe interface.

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