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A comprehensive study of atomic-layer deposited thulium oxide (Tm2O3) on germanium has been conducted using x-ray photoelectron spectroscopy (XPS), vacuum ultra-violet variable angle spectroscopic ellipsometry, high-resolution transmission electron microscopy (HRTEM), and electron energy-loss spectroscopy. The valence band offset is found to be 3.0±60.2 eV for Tm2O3/p-Ge from the Tm 4d centroid and Ge 3p3/2 charge-corrected XPS core-level spectra taken at different sputtering times of a single bulk thulium oxide sample. A negligible downward band bending of ~0.12 eV is observed during progressive differential charging of Tm 4d peaks. The optical band gap is estimated from the absorption edge and found to be 5.77 eV with an apparent Urbach tail signifying band gap tailing at ~5.3 eV. The latter has been correlated to HRTEM and electron diffraction results corroborating the polycrystalline nature of the Tm2O3 films. The Tm2O3/Ge interface is found to be rather atomically abrupt with sub-nanometer thickness. In addition, the band line-up of reference GeO2/n-Ge stacks obtained by thermal oxidation has been discussed and derived. The observed low reactivity of thulium oxide on germanium as well as the high effective barriers for holes (~3 eV) and electrons (~2 eV) identify Tm2O3 as a strong contender for interfacial layer engineering in future generations of scaled high-κ gate stacks on Ge. [ABSTRACT FROM AUTHOR]

In this work, the impact of the local and remote Coulomb scattering mechanisms on electron and hole mobility are investigated. The effective mobilities in quasi-planar finFETs with TiN/Hf0.4Si0.6O/SiO2 gate stacks have been measured at 300 K and 4 K. At 300 K, electron mobility is degraded below that of bulk MOSFETs in the literature, whereas hole mobility is comparable. The 4 K electron and hole mobilities have been modeled in terms of ionized impurity, local Coulomb, remote Coulomb and local roughness scattering. An existing model for remote Coulomb scattering from a polycrystalline silicon gate has been adapted to model remote Coulomb scattering from a high-κ/SiO2 gate stack. Subsequently, remote charge densities of 8 × 1012 cm-2 at the Hf0.4Si0.6O/SiO2 interface were extracted and shown to be the dominant Coulomb scattering mechanism for both electron and hole mobilities at 4 K. Finally, a Monte Carlo simulation showed remote Coulomb scattering was responsible for the degraded 300 K electron mobility. [ABSTRACT FROM AUTHOR]

We explore the possibility to define an effective mass parameter to describe hole transport in inversion layers in bulk MOSFETs and silicon-on-insulator devices. To do so, we employ an accurate and computationally efficient self-consistent simulator based on the six-band k·p model. The valence band structure is computed for different substrate orientations and silicon layer thicknesses and is then characterized through the calculation of different effective masses taking account of the channel direction. The effective masses for quantization and density of states are extracted from the computed energy levels and subband populations, respectively. For the transport mass, a weighted averaging procedure is introduced and justified by comparing the results with hole mobility from experiments and simulations. [ABSTRACT FROM AUTHOR]

The electrical conduction across a two-dimensional photonic crystal (PhC) fabricated by Ar/Cl2 chemically assisted ion beam etching in n-doped InP is influenced by the surface potential of the hole sidewalls, modified by dry etching. Carrier transport across photonic crystal fields with different lattice parameters is investigated. For a given lattice period the PhC resistivity increases with the air fill factor and for a given air fill factor it increases as the lattice period is reduced. The measured current-voltage characteristics show clear ohmic behavior at lower voltages followed by current saturation at higher voltages. This behavior is confirmed by finite element ISE TCAD™ simulations. The observed current saturation is attributed to electric-field-induced saturation of the electron drift velocity. From the measured and simulated conductance for the different PhC fields we show that it is possible to determine the sidewall depletion region width and hence the surface potential. We find that at the hole sidewalls the etching induces a Fermi level pinning at about 0.12 eV below the conduction band edge, a value much lower than the bare InP surface potential. The results indicate that for n-InP the volume available for conduction in the etched PhCs approaches the geometrically defined volume as the doping is increased. [ABSTRACT FROM AUTHOR]

We report on the microscopic mapping of specific contact resistances (ρ[sub c]) and long-term reliability tests using sputtered titanium tungsten (TiW) ohmic contacts to highly doped n-type epilayers of 4H-silicon carbide. The TiW ohmic contacts showed good uniformity with low contact resistivity of 3.3 × 10[sup -5] Ω cm². Microscopic mapping of the ρ[sub c] showed that the ρ[sub c] had a distribution that decreased from the center to the edge of the wafer. This distribution of the ρ[sub c] is caused by variation of the doping concentration of the wafer. Sacrificial oxidation at high temperature partially recovered inductively coupled plasma etch damage. TiW contacts with platinum and gold capping layers have stable specific contact resistance at 500 and 600 °C in a vacuum chamber for 308 h. [ABSTRACT FROM AUTHOR]

The strained Si/Si[sub 1-x]Ge[sub x]/Si layer heterostructure heat treated from 700°C to 950°C in Ar (annealing) or 0[sub 2]-C[sub 2]H[sub 2]Cl[sub 2] (oxidation) was characterized using high-resolution x-ray diffraction in combination with Rutherford backscattering. Only small changes to the structure are observed up to 800 °C, within the resolution limits of diffraction and backscattering. Severe strain relaxation occurs at 950 °C and the heterostructure tends to relax more during annealing in Ar than during oxidation in 0[sub 2]-C[sub 2]H[sub 2]Cl[sub 2]. The strain relaxation is mainly caused by interdiffusion of Si and Ge rather than formation of misfit dislocations. Diffusion of Si interstitials generated during oxidation into the heterostructure is suggested as the cause responsible for the less pronounced interdiffusion of Si and Ge in the oxidized samples. [ABSTRACT FROM AUTHOR]

AlGaN/4H–SiC heterojunction diodes with varying composition of Al have been fabricated. Five different compositions were investigated, GaN, Al[sub 0.1]Ga[sub 0.9]N, Al[sub 0.15]Ga[sub 0.85]N, Al[sub 0.3]Ga[sub 0.7]N, and Al[sub 0.5]Ga[sub 0.5]N, along with a 4H–SiC homojunction diode for comparison. The turn on voltage was around 1 V, and the ideality factor between 1 and 2 for all heterojunction diodes except for the Al[sub 0.3]Ga[sub 0.7]N diode. This diode had an ideality factor between 2 and 3, and also showed a much lower series resistance, indicating a change in transport mechanism across the junction. A tunnel assisted recombination model was analyzed and compared to the extracted values of the GaN diode. The model agreed well with both current–voltage and capacitance–voltage measurements for this diode. This model was not applied to the other samples, since their characteristics could not be explained by a simple mechanism. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Provides information on an experimental study investigating the influence of the addition of Co and Ni on the formation of epitaxial semiconducting beta-FeSi2. Methodology used to conduct the experiment; Results of the experiment; Information on reactive deposition epitaxy; Discussion on the results.

Presents a study that investigated thin-film growth and compositional effects of c-axis oriented YBa[sub2]Cu[sub3]O[sub7-x] thin films synthesized by metalorganic chemical vapor deposition. Procedures used for the film synthesis; Electrical and structural characterization of the films; Analysis of the results for the single cation films.

Presents a study on the influence of oxygen on tungsten silicide formation deposited from tungsten hexafluoride. Factor which affect the silicidation rate; Discussion of silicide formation on oxygen-implanted silicon; Role of oxygen and fluorine in the silicide formation process.

Studies the use of heat treatment in the removal of fluorine from a polycrystalline silicon gate structure in a chemical vapor deposition system. Details on the experiment; Results of the study; Conclusions.

Focuses on a study which investigated the isotope separation and growth mechanisms of nickel silicides by secondary ion mass spectrometry. Formations of Ni[sub2]Si and nickel silicide; Experimental techniques and results; Discussion and conclusions.

Presents a quantitative study of oxygen behavior during the formation of chromium disilicide and titanium disilicide. Extent of the silicide formation monitored by backscattering spectrometry; Mass and energy dispersive recoil spectrometry; Oxygen depth profile from resonant scattering for a chromium samples.

Presents information on a study which discussed the redistribution of dopants during the solid-phase reaction of chromium (Cr) with silicon (Si) substrates to form CrSi[sub2]. Silicide growth and profile calibrations; Discussion on dopant redistribution; Application of Rutherford backscattering spectrometry on dopants investigated.