Soft x-ray photoelectron spectroscopy with synchrotron radiation was employed to study the valence-band offsets for the HfO2/SiO 2/Si and HfO2/SiOxNy/Si systems. We obtained a valence-band offset difference of -1.05±0.1eV between HfO 2 (in HfO2/15ÅSiO2/Si) and SiO 2 (in 15 Å SiO2/Si). There is no measurable difference between the HfO2 valence-band maximum positions of the HfO2/10ÅSiOxNy/Si and HfO 2/15ÅSiO2/Si systems. © 2002 American Institute of Physics

Fe-Pt thin-film alloys have been grown by electrodeposition at potentials positive to that required to deposit elemental Fe. X-ray diffraction studies indicate the formation of fine grained face centered cubic alloys, while Rutherford backscattering spectrscopy and energy-dispersive X-ray spectroscopy reveal substantial incorporation of oxygen in the FePt deposits. The Fe-Pt codeposition process is driven by the negative enthalpy associated with alloy formation. The experimentally determined relationship between alloy composition and the iron group underpotential was found to be in reasonable agreement with free energy calculations for the binary alloy system, based on thermochemical data.There is currently considerable interest in FePt as a high-density perpendicular recording medium, due to the high magnetocrystalline anisotropy of the L1 0 phase. The significant challenges of achieving an appropriately oriented L1 0 phase, while maintaining the required grain ͑or particle͒ size of less than 5 nm, remain unsolved, despite considerable effort. 1-3 FePt has attracted additional interest due to its shape-memory properties, and Invar effects, both of potential utility in microelectromechanical systems ͑MEMS͒. 4 In addition to these useful physical properties Fe-Pt and related alloys have potential application as CO-tolerant electrocatalyst in polymer electrolyte fuel cells. 5,6 In all the above applications, process control during synthesis is of central importance.A variety of means have been used to produce Fe-Pt and similar alloys ranging from vacuum methods like MBE and sputtering 2,3,7,8 to electrodepositon 9-13 of thin films or fine particle production by solution phase chemical reduction. 1,14-16 One particular advantage of electrochemical methods is the ability to easily specify and control the supersaturation while monitoring its effect on growth kinetics.Herein we examine the factors affecting alloy composition during electrodeposition from an aqueous electrolyte containing chlorocomplexes of platinum and iron. Traditional alloy deposition studies largely focus on growth in the overpotential domain. 17 In this case, the composition is controlled by the relative rate of reduction of the constituents occurring in a potential regime where both species can be deposited in their elemental form. The desired differential activity, required for a particular alloy composition, is achieved by judicious choice of component concentrations and complex forming ligands. In contrast, in this study the use of the free energy of alloy formation to control alloy composition is demonstrated.The thermodynamic basis for alloy formation is well established. In fact, high temperature electrochemical potential ͑emf͒ measurements have contributed significantly toward the understanding of phase equilibria and the construction of phase diagrams. A necessary condition for binary alloy A 1Ϫx B x formation is equality of the electrochemical potential of the respective constituentswhere E i is the Nernst potential given by ͓2͔The free e...

is, graphene, transition metal dichalcogenides (TMDs), [ 2,3 ] topological insulators, [ 4 ] h-BN [ 5 ] and h-AlN, [ 6 ] as well the recent phosphorene, [ 7 ] silicene, [ 8 ] and germanene [ 9 ] provide the ability to control the channel thickness at atomic level. This characteristic translates into improved gate control over the channel barrier and into reduced short-channel effects, thus paving the way toward ultimate miniaturization and new device concepts. Recently, 2D transition metal dichalcogenides, have proven to be promising candidates for electronics and optoelectronic applications. [10][11][12][13][14][15][16] From a pioneering perspective, the availability of TMDs with different work functions and band structures guarantees a great potential for band gap engineering of heterostructures. These systems are fundamentally different and more fl exible than traditional heterostructures composed of conventional semiconductors. In particular, due to the weak interlayer interaction, a TMD molecular layer grows from the beginning with its own lattice constant forming an interface with reduced amount of defects. The relaxed lattice matching condition permits to combine almost any layered material and create artifi cial heterojunctions with designed band alignment. 2D heterostructures