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The plasmon frequencies of a general core/double-shell structure are studied by plasmon hybridization method, and three distinct plasmon modes (ω0, ω+, and ω−) are found, in which the value of ω0 is always stable, and ω+ as well as ω− is variable with the radius ratios. The influences of dielectric effect and permittivity difference between metallic core and outer-shell are also analyzed thoroughly. The origins of the stability and tunability of this core/double-shell structure are explored by comparing the charge densities and local field distributions at interfaces. Furthermore, our model can be simplified to different structures including metallic-core/dielectric-shell, dielectric-core/metallic-shell, metallic-core/metallic-shell and its complementary structures, of which the corresponding plasmon modes are also studied and compared with experimental results.

The effect of nitrogen incorporation on the band alignment and electrical properties of HfTiO gate dielectric complementary metal-oxide-semiconductor (MOS) capacitors has been investigated by spectroscopy ellipsometry, x-ray photoelectron spectroscopy, and electrical measurements. Reduction in optical band gap and band offsets has been detected. However, improved electrical properties have been achieved from HfTiON gate dielectric MOS capacitors attributed to the nitrogen-induced reduction in oxygen-related traps and the improved interface quality. Although there is a nitrogen-induced reduction in band gap and band offset, the sufficient barrier heights still makes HfTiON a promising high-k gate dielectric candidate for proposed near-future complementary metal-oxide-semiconductor applications.

In this letter, treatment of GaAs surface by using dimethylaluminumhydride-derived AlON passivation layer prior to HfO2 deposition is proposed to solve the issue of Fermi level pinning. It has been found that AlON passivation layer effectively suppresses the oxides formation and leads to the Fermi level unpinning at the interface between GaAs and HfO2. Based on analysis from metal-oxide-semiconductor capacitors of Au/HfO2/AlON/GaAs stack, excellent capacitance-voltage characteristics with saturated accumulation capacitance and reduced leakage current have been achieved, which may originate from the decrease in the interface state density and the increase in the conduction band offset.

Fermi level pinning attributed to oxides at the GaAs/high-k interface is a major obstacle to develop GaAs-based metal-oxide-semiconductor devices with high performance. In this letter, thermal nitridation treatment of GaAs surface prior to the high-k deposition is proposed to solve the issue of interface pinning. Results have confirmed that nitridation passivation effectively suppresses the oxides formation and leads to a shift in the Fermi level toward the conduction band minimum on the GaAs surface, which increases the conduction band offset at the GaAs/AlOxNy interface, followed by a saturated accumulation capacitance with reduced gate leakage current.

The effect of nitrogen atom doping on the optical properties and dielectric constant of HfO2 films has been systematically investigated. Spectroscopic ellipsometry was employed to investigate the optical properties of nitrogen incorporated HfO2 films. The values of average oscillator strength and average oscillator position extracted from spectroscopic ellipsometry demonstrated that nitrogen incorporation could influence the dipole oscillator strength and oscillator position of HfO2. A physical model of dipole structures was proposed to verify the enhancement of dielectric constant of HfO2 films by nitrogen incorporation.

The effect of N concentration on the band gap and band offsets of HfOxNy films has been systematically investigated. It was found that the band gap as well as the band offsets of HfOxNy films decreased with the increase of N concentration. When the N concentration reached 16.3%, the conduction band offset (ΔEc) reduced to be 0.88eV, which is smaller than the minimal requirement of ΔEc values for high-k dielectrics and, thus, leads to unacceptably high leakage currents. Therefore, nitrogen concentration should be carefully controlled to guarantee excellent properties of nitrogen incorporated high-k dielectrics.

Effects of nitrogen incorporation on interfacial property, band gap, and band alignments of high-k Y2O3 gate dielectrics have been investigated. It was found that the incorporation of nitrogen into Y2O3 films can effectively suppress the growth of the interfacial layer between Y2O3 and Si substrate. The incorporation of nitrogen into Y2O3 films leads to the reduction of band gap and valence band offset, but not the conduction offset of Y2O3 films. High temperature annealing will help to increase the band gap and valence band offset of YOxNy film due to the release of the interstitial N atoms.

Temperature-dependent interfacial chemical bonding states and band alignment of HfOxNy∕SiO2∕Si gate stacks have been investigated by X-ray photoemission spectroscopy (XPS) and spectroscopic ellipsometry (SE). By means of the chemical shifts of Hf 4f, Si 2p, O 1s, and N 1s core-level spectra, it has been found that the chemical stability of the HfOxNy∕SiO2∕Si stacks strongly depends on the annealing temperature. Analysis of temperature-dependent band alignment of HfOxNy∕SiO2∕Si stacks suggests that the valence band offset ΔEv increases slowly from 1.82eV for as-grown film to 2.55eV for annealed film at 700°C; however, the values of conduction band offset ΔEc only demonstrates a slight change in the vicinity of 1.50eV. From the band offset viewpoint, HfOxNy∕SiO2∕Si gate stack could be a promising candidate for high-k gate dielectrics.

The thermal expansion of as-prepared and annealed silver nanowires embedded in anodic alumina membranes with different diameters was studied by in situ x-ray diffraction in the temperature range from 25to800°C. For both the as-prepared and annealed samples, the coefficients of thermal expansion have “V” shape change as the diameters increase; and the minimum values of the coefficients of thermal expansion do not correspond to the same diameters of nanowires. The collective effects of the surface tension, the limit effects of anodic alumina membrane, and the vacancies incorporated into the silver lattice were responsible for the thermal expansion.

Thermal expansion of as-prepared and annealed ordered arrays of silver nanowires embedded in anodic alumina membranes (AAMs) was studied by in situ x-ray diffraction measurement in the temperature range from 25to800°C. The axial thermal expansion coefficient (TEC) for the as-prepared nanowires is 6.35×10−9∕°C and 6.02×10−6∕°C below and above 650°C, respectively. However, the TEC of the annealed sample turns from 2.32×10−6∕°Cto12.06×10−6∕°C when the temperature is above 350°C. The collective effects of the intrinsic expansion, surface pressure, the limit effect of AAM, and the vacancies incorporated into the silver lattice were responsible for the thermal expansion.

The melting behavior of Zn nanowires embedded in the holes of porous anodic alumina membrane with different diameters was studied by using the differential scanning calorimetry. The crystalline structure and morphology of Zn nanowire arrays were characterized by x-ray diffraction and transmission electron microscopy. The melting temperature of Zn nanowire arrays shows the strong dependence on nanowire sizes. The melting temperature was curvilinear with the reciprocal of the diameter of nanowires with the change of the diameter, which was discussed in terms of size-dependent heat of fusion change.