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Author(s): F. U. Renner (corresponding author) [1, 2]; A. Stierle [1]; H. Dosch [1]; D. M. Kolb [3]; T.-L. Lee [2]; J. Zegenhagen [2] Corrosion destroys more than three per [...]

A study was conducted to analyze the microstructure of YBa2Cu3O(sub 7-delta) thin films prepared on vicinal SrTiO3(001) as a function of the vicinal angle by x-ray diffraction utilizing the two-dimensional q-scan method. The two-dimensional resolution function of a four-circle diffractometer was utilized to unfold the measured intensities to examine the two-dimensional peak shape of orientations. Results indicated that the miscut of a SrTiO3(001) substrate correlated with the anisotropic defect structure of the film.

The polarity of a one micron thick GaN film grown by molecular beam epitaxy on an alpha-Al2O3(0001) single crystal was obtained through the x-ray standing wave method. The standing wave was produced by x-ray diffraction from the GaN film. The Ga K(sub alpha) fluorescence yield was indicated as a function of incidence angle within the range of the GaN(0002) reflection. Data analysis revealed that the film has grown with N polarity or that the nitrogen atoms reside in the top half of the wurtzite (0001) bilayers.

We present a detailed analysis of the impact of high temperature annealing on the chemical and electronic properties of TiN/HfSixOyNz/SiOxNy/Si gate stacks, where an ultra-thin LaOx capping layer (0.4-1 nm) is inserted between the TiN metal gate and the HfSixOyNz dielectric. From our experimental results, we demonstrate that La atoms diffuse through the entire nitrided hafnium silicate and reach the SiOxNy interfacial layer to form a La-silicate. In addition, hard x-ray photoelectron spectroscopy analysis highlights the band alignments' shift of the gate stacks, which is well related to Vfb shifts based on an interfacial dipole and/or fixed charges model. Finally, this study reveals that the Vfb roll-off phenomenon is amplified with an increasing amount of La atoms near the substrate interface. A correlation between LaOx thickness and interface trap density (Dit) is observed, and a mechanism explaining the roll-off behavior is proposed. [ABSTRACT FROM AUTHOR]

We investigated origins of the resistivity change during the forming of NiO based resistive random access memories in a nondestructive way using hard x-ray photoelectron spectroscopy. Energy shifts and bandgap states observed after switching suggest that oxygen vacancies are created in the low resistive state. As a result conduction may occur via defects such as electrons traps and metallic nickel impurities. Migration of oxygen atoms seems to be the driving mechanism. This provides concrete evidence of the major role played by oxygen defects in decreasing resistivity. This is a key point since oxygen vacancies are particularly unstable and thus difficult to identify by physico-chemical analyses. [ABSTRACT FROM AUTHOR]

Metal-organic interfaces based on copper-phthalocyanine monolayers are studied in dependence of the metal substrate (Au versus Cu), of its symmetry [hexagonal (111) surfaces versus fourfold (100) surfaces], as well as of the donor or acceptor semiconducting character associated with the nonfluorinated or perfluorinated molecules, respectively. Comparison of the properties of these systematically varied metal-organic interfaces provides new insight into the effect of each of the previously mentioned parameters on the molecule-substrate interactions. [ABSTRACT FROM AUTHOR]

The structure of ultrathin epitaxial Pr2O3 films on Si(111) was studied by synchrotron radiation-grazing incidence x-ray diffraction. The oxide film grows as hexagonal Pr2O3 phase with its (0001) plane attached to the Si(111) substrate. The hexagonal (0001) Pr2O3 plane matches the in-plane symmetry of the hexagonal Si(111) surface unit cell by aligning the (10&1bar;0)Pr2O3 along the (11&2bar;) Si directions. The small lattice mismatch of 0.5% results in the growth of pseudomorphic oxide films of high crystalline quality with an average domain size of about 50 nm. The critical thickness tc for pseudomorphic growth amounts to 3.0± 0.5 nm. The relaxation of the oxide film from pseudomorphism to bulk behavior beyond tc causes the introduction of misfit dislocations, the formation of an in-plane small angle mosaicity structure, and the occurence of a phase transition towards a (111) oriented cubic Pr2O3 film structure. The observed phase transition highlights the influence of the epitaxial interface energy on the stability of Pr2O3 phases on Si(111). A mechanism is proposed which transforms the hexagonal (0001) into the cubic (111) Pr2O3 epilayer structure by rearranging the oxygen network but leaving the Pr sublattice almost unmodified. [ABSTRACT FROM AUTHOR]

We investigated the structure and transport properties of GdBa[sub 2]Cu[sub 3]O[sub 7] films on SrTiO[sub 3](001) and NdGaO[sub 3](001). We found that the films can be grown pseudomorphically up to at least 42 nm thickness on SrTiO[sub 3] whereas the critical thickness is less than 14 nm for films on NdGaO[sub 3]. The carrier density of pseudomorphic films on SrTiO[sub 3] is tuned by the pseudomorphic stress field and films on SrTiO[sub 3] show higher T[sup *] and lower T[sub c] compared to films of the same thickness on NdGaO[sub 3]. For a 28 nm thick GdBa[sub 2]Cu[sub 3]O[sub 7] film on SrTiO[sub 3], the hole density per CuO[sub 2] plane is reduced to 0.12, compared to 0.16 for the optimally doped and stress-free RBa[sub 2]Cu[sub 3]O[sub 7]. The measured temperature dependence of J[sub c] can be understood and described by interface stress pinning. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The structure of ultrathin epitaxial Pr2O3 films on Si(111) is studied by synchrotron radiation-grazing incidence x-ray diffraction. The oxide film grows as hexagonal Pr2O3 phase with its (0001) plane attached to the Si(111) substrate.