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X-ray photoemission spectroscopy (XPS) and reflection high-energy electron diffraction (RHEED) have been used to investigate the initial stages of InP growth on H-terminated Si and native Si oxide surfaces. By annealing at 800°C, the H-terminated Si surface exhibits a (2×1) RHEED pattern while the native oxide surface just shows a halo RHEED pattern. After exposing them to P2 flux, the Si(2×1) clean surface exhibits a (2×1) RHEED pattern while the native Si oxide layer always shows the halo RHEED pattern. XPS measurement reveals that while P atoms adsorb on the Si(2×1) surface, the adsorption of P atoms does not take place on the native Si oxide surfaces. In consequence of the difference in the adsorption of P atoms between the clean Si and Si oxide surfaces, InP does not grow on the Si oxides at temperatures above 450°C while InP grows on the clean Si substrates. Based on the findings, we will discuss the mechanism of the selective area growth of InP on patterned Si substrates with Si oxide mask in terms of desorption of In and P. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the influence of hydrogen absorption on crystal quality of dihydride of Y by selecting the type of a cap layer for the Y surface from non-capped, Gd capped, Pd capped, and Ni capped cases. Our experiments revealed that (i) the grain size (D) of YH2 does not correlate with that of Y, but is strongly affected by the type of cap layer; the presence of Pd layer reduces D by a factor of when hydrogenated, whereas Ni capped, Gd capped, and non-capped cases increase D by a factor of when hydrogenated, (ii) as deposited non-capped and Pd capped Y films having high crystal textures (T) yield YH2 films also having high T but a slight difference in T present in as deposited films is non-linearly enhanced upon hydrogenation so that the highest T value obtained in this study was found to be larger than those reported so far. [Copyright &y& Elsevier]

Abstract: Crystal growth of pure phases of Gd x Y1−x H2 ( ) was successfully carried out by depositing Gd x Y1−x films and their hydrogenation, the growth results of which were investigated by X-ray diffraction measurements as well as temperature (T) dependence of magnetic susceptibility ( ). The fcc lattice constant in Gd x Y1−x H2 is found to be linearly increased with increasing x. Behavior characteristic to the para-to-antiferromagnetic transition are clearly observed in the curve for x=0.39, 0.47, 0.76, and 1.0 cases. The Néel temperature (T N ) is found to be linearly decreased with decreasing x from x=1.0 (GdH2), and is predicted to show at by extrapolating T N from large x region, implying the antiferromagnetic order disappears at . The quasi-zero Hall effect was observed for x=0, 0.19, 0.37, 0.39, and 0.47 cases, whereas a moderate Hall effect is observed for x=0.76 and 1.0 cases. The type of Hall effect is also discussed. [Copyright &y& Elsevier]

Abstract: Local structural change around Cr atoms in GaN-based diluted magnetic semiconductor GaCrN grown by radio frequency plasma-assisted molecular-beam epitaxy was studied with fluorescent X-ray absorption fine structure (XAFS) and X-ray diffraction measurements. The lattice constant of Ga1-xCrxN depends linearly on x up to and it approaches to that of non-doped GaN above x of 4.7%. It was found from our XAFS study that the majority of Cr atoms substitute the Ga lattice sites of GaN and that the critical Cr concentration of solid solution is around . At the critical Cr concentration, onset of the formation of NaCl-type CrN-like structure occurs, and above the critical concentration, the local structure around Cr atoms transforms to a completely CrN-like structure. Our X-ray absorption near-edge structure studies also indicate a drastic change in local electronic structure of Ga1-xCrxN at x between 4% and 4.7%. This is ascribed to the fact that the atomic configuration of Cr and N undergoes a drastic transition from the substitutionally incorporated GaCrN into the CrN-like atomic configuration. The local structural change into NaCl-type CrN was also supported by the XAFS pre-edge structures and the polarized XANES spectra. [Copyright &y& Elsevier]