The control factors controlling the growth of native silicon oxide on silicon (Si) surfaces have been identified. The coexistence of oxygen and water or moisture is required for growth of native oxide both in air and in ultrapure water at room temperature. Layer-by-layer growth of native oxide films occurs on Si surfaces exposed to air. Growth of native oxides on n-Si in ultrapure water is described by a parabolic law, while the native oxide film thickness on n+-Si in ultrapure water saturates at 10 Å. The native oxide growth on n-Si in ultrapure water is continuously accompanied by a dissolution of Si into the water and degrades the atomic flatness at the oxide-Si interface, producing a rough oxide surface. A dissolution of Si into the water has not been observed for the Si wafer having surface covered by the native oxide grown in air. Native oxides grown in air and in ultrapure de-ionized water have been demonstrated experimentally to exhibit remarkable differences such as contact angles of ultrapure water drops and chemical binding energy. These chemical bond structures for native oxide films grown in air and in ultrapure water are also discussed.

Native silicon (Si) oxide growth on Si (100) wafers in air and in ultrapure water at room temperature requires coexistence of water and oxygen in the air and ultrapure water ambients. The growth rate data on n-, n+-, and p+-Si (100) in air indicate layer-by-layer growth of an oxide. The growth rate on n-Si (100) in ultrapure water may be governed by a parabolic law. For native oxide growth in ultrapure water, the number of Si atoms dissolved in ultrapure water is over one order of magnitude larger than the number of Si atoms contained in the grown native oxide film. The structural difference between the native oxide film in air and in ultrapure water is also discussed.

We propose the metal-assisted chemical etching of Ge surfaces in water mediated by dissolved oxygen molecules (O2). First, we demonstrate that Ge surfaces around deposited metallic particles (Ag and Pt) are preferentially etched in water. When a Ge(100) surface is used, most etch pits are in the shape of inverted pyramids. The mechanism of this anisotropic etching is proposed to be the enhanced formation of soluble oxide (GeO2) around metals by the catalytic activity of metallic particles, reducing dissolved O2 in water to H2O molecules. Secondly, we apply this metal-assisted chemical etching to the nanoscale patterning of Ge in water using a cantilever probe in an atomic force microscopy setup. We investigate the dependences of probe material, dissolved oxygen concentration, and pressing force in water on the etched depth of Ge(100) surfaces. We find that the enhanced etching of Ge surfaces occurs only when both a metal-coated probe and saturated-dissolved-oxygen water are used. In this study, we present the possibility of a novel lithography method for Ge in which neither chemical solutions nor resist resins are needed.

An error in the paper by Tamenori et al. [(2011), J. Synchrotron Rad. 18, 747-752] is corrected.In the second paragraph of x3.2 of Tamenori et al. (2011), we had provided incorrect fluorescence decay probability values for Mn L 23 -shell ionization (0.0063) and O K-shell ionization (0.05). The correct fluorescence decay probability value of Mn L 23 -shell ionization is 0.005 and that of O K-shell ionization is 0.0083 .Consequently, we had overestimated the difference between the fluorescence decay probabilities of Mn L 23 -shell and O K-shell ionization.Based on the correct fluorescence decay probability values, the Mn L 23 -shell ionization value is about 60% of the O K-shell ionization value. This ratio supports a qualitative interpretation of the dip structure that appeared in the NEXAFS spectra of a MnO crystal [ Fig. 3 of Tamenoriet al. (2011)]. Furthermore, the model proposed in the original paper was also corroborated by two-dimensional fluorescence measurement results, which have been presented in the last paragraph of x3.2. Therefore, the overall conclusions of the original paper remain unchanged.We thank Professor Toshiaki Ohta of Ritsumeikan University for drawing our attention to this error. The objective of this article is to describe the capability of a two-dimensional (2D) approach to X-ray absorption near-edge structure (XANES) measurement by means of a partial fluorescence yield (PFY) method. 2D-XANES measurements were achieved by using a silicon drift detector as an energydispersive fluorescence detector. The advantage of this technique is that it allows full surveys of X-ray fluorescence data that are lost in conventional PFY measurements. The availability of a map approach was demonstrated by applying it to XANES measurements in both a diluted (Mn-doped nanodiamond) and a concentrated (MnO crystal) manganese sample. The 2D approach clearly distinguished between the PFY spectra of Mn and O atoms, where absorption edges of both elements are close to each other. Further, the 2D approach extracted an unambiguous PFY spectrum of phosphorus in the XANES measurement of SS304 (P < 0.045 wt%).

We consider the polarization of unstable type-IIB D0-branes in the presence of a background five-form field strength. This phenomenon is studied from the point of view of the leading terms in the non-abelian Born Infeld action of the unstable D0-branes. The equations have SO(4) invariant solutions describing a non-commutative 3-sphere, which becomes a classical 3-sphere in the large-N limit. We discuss the interpretation of these solutions as spherical D3-branes. The tachyon plays a tantalizingly geometrical role in relating the fuzzy S 3 geometry to that of a fuzzy S 4 .