Narrow Results

The following sections are included:

• Introduction

• General Considerations
  • Absorption Coefficient and Photon Penetration Depth
  • Escape Depths of Various Yields
  • Instrumentation

• Applications
  • Ni/Si(100): Evolution of Nickel Silicide Thin Films
    • General Considerations
    • Ni and Si K edge XANES for the Blanket Films
    • Ni and Si L edge XANES for the Blanket Films and Submicron Lines
  • Al Diffusion Through a TiN_x Diffusion Barrier on Si(100)
    • General Considerations
    • Al K edge: TEY
    • Al K edge: FLY
    • Al L edge TEY and FLY
  • Porous Silicon
    • General Considerations
    • Synchrotron Radiation Induced Luminescence
    • XEOL and Optical XAFS at the Si K edge and the Origin of Luminescence from PS
    • XEOL and Optical XAFS at the Si L_3,2 edge
    • A MCMD Study of the Distribution of Luminescence Sites

• Summary

• Acknowledgments

• References

• Appendix: Recent Publications Using Multidetection X-ray Absorption Spectroscopy (MD-XAS) Techniques

The porphyrin macrocycle is one of the most frequently investigated functional molecular entities and can be incorporated into advanced functional nanomaterials upon formation of organized nanostructures. Thus, study of the science and technology of porphyrin assemblies has attracted many organic, biological and supramolecular chemists. A wide variety of nanostructures can be obtained by supramolecular self-assembly because the porphyrin moiety is amenable to chemical modifications through thoughtful synthetic design and moderate preparative effort. Some recent developments in porphyrin assembly, obtained through various supramolecular approaches, are briefly summarized. Topics described in this review are classified into four categories: (i) non-specific assemblies; (ii) specific assemblies; (iii) assemblies in organized films; (iv) molecular-level arrangement. We present examples in the order of structural precision of assemblies.

X-ray absorption fine structure (XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials, environmental sciences, and so on. In this chapter, we introduce the XAFS principles, including its basic theory, data analysis and experiment, from the view point of practical use. To show its strength as a local structure probe, applications of XAFS in various functional materials are introduced, covering nanoparticles and catalysts, magnetic semiconductors, thin film materials, complex compounds, in situ probing of the nucleation and growth processes of nanomaterials, as well as operando study of catalysts under working conditions.

In addition, we also briefly introduce some relatively new XAFS-related techniques, such as time-resolved and space-resolved XAFS techniques.

We present results of first principle calculations of the Casimir force between Si films of nanometric size, which show that it depends significantly upon the configuration of the surface atoms, and give evidence of the importance of surface states.

The development of long-wave Marangoni instability under the action of a heat flux modulated in time is studied. The critical Marangoni number for the deformational instability is obtained as a function of frequency.

In this study, nc-ZnO films deposited in a Pulsed Laser Deposition (PLD) system at various temperatures were used to fabricate high performance transistors. As determined by Transmission Electron Microscope (TEM) images, nc-ZnO films deposited at a temperature range of 25°C to 400°C were made of closely packed nanocolums showing strong orientation. The influences of film growth temperature and post growth annealing on device performance were investigated. Various gate dielectric materials, including SiO₂, Al₂O₃, and HfO₂ were shown to be suitable for high performance device applications. Bottom-gate FETs fabricated on high resistivity (>2000 ohm-cm) Si substrates demonstrated record DC and high speed performance of any thin film transistors. Drain current on/off ratios better than 10¹² and sub-threshold voltage swing values of less than 100mV/decade could be obtained. Devices with 2μm gate lengths produced exceptionally high current densities of >750mA/mm. Shorter gate length devices (L_G=1.2μm) had current and power gain cut-off frequencies, f_T and f_max, of 2.9GHz and 10GHz, respectively.

Residual stress is one of the important parameters of thin films, which can seriously affect the properties, performance and long-term stability of thin films. Stress measurement techniques are therefore essential for both process development and process monitoring. This paper presents a novel symmetric micro strain gauge which can be in situ fabricated. The structure is modeled and simulated in ANSYS. Both compressive and tensile stress can be measured via this strain gauge and the resolution can reach to 0.0005% with optimized dimension.

Rapid technological advancements in recent years have necessitated the creation of energy-related devices. Due to their unique properties, including an exceptional cycling life, safe operation, low processing cost, and a higher power density than batteries, supercapacitors (SCs) have been identified as one of the most promising candidates to meet the demands of human sustainability. To increase the energy density of SCs, several advanced electrode materials and cell designs have been researched during the past few years. Utilizing the Faradaic charge storage process of transition metal cations, transition metal compounds have recently received attention as prospective electrode materials for SCs with high energy densities. In this work, the structure, morphology and electrochemical properties of molybdenum oxide (MoO₃) films deposited via thermal evaporation technique and annealed at various temperatures were systematically investigated in order to examine the potential use of MoO₃ for supercapacitors. Electrochemical analysis confirmed the pseudocapacitance characteristics of the synthesized films. The annealing temperature affects the oxidation and reduction observed in the cyclic voltammetry (CV) plots. Areal capacitance of thin films annealed at 150°C was found to be maximum and this could be attributed to the formation of hollow tube-like nanostructures which provided more active sites, than films annealed at higher temperatures. This also influences the charge storage ability of the synthesized films. It would be logical to assume that additional research in this area will result in more interesting discoveries and, eventually, the vi-ability of those promising Mo-based compounds in high-tech energy storage systems.