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The spectrum of localized hole states (traps) in amorphous silicon nitride, a-Si3N4, is experimentally studied using the method of thermally stimulated depolarization. The experiment is compared with theoretical calculations using three models of the energy spectrum of traps: discrete spectrum (monoenergetic trap), continuous spectrum, and Gaussian trap distribution. The experiment is quantitatively described by a model of a discrete spectrum of traps with an energy of 1.15 eV and a width of no more than 0.01 eV. In the case of a continuous and Gaussian spectrum of traps, the contribution to depolarization is made by the deepest traps. The blurring of the trap energy level in a-Si3N4 due to the absence of long-range order (fluctuations in the Si–N bond length and fluctuations in the N–Si–N and Si–N–Si angles) does not exceed 0.01 eV. [ABSTRACT FROM AUTHOR]

Organosilicate-glass-based low-κ films containing both terminal methyl groups and an ethylene bridge between the silicon atoms are spin-on deposited by using 1,2-bis(trimethoxysilyl)ethane and methyltrimethoxysilane, Brij30 template, and thermal curing. The chemical composition, porosity, and internal defects are studied using Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, electron energy loss spectroscopy, UV induced luminescence, and ellipsometric porosimetry. It was found that the studied films contain oxygen-deficient centers (Si—Si bonds). The high defect density of the states near the valence-band edge of the studied low-κ films leads to a relatively small bandgap value of about 6.3 eV. The current–voltage characteristics at different temperatures were analyzed using six theoretical charge transport models where the transport is limited by the traps ionization. It was found that the best qualitative and quantitative agreement between the calculations and experimental data is achieved by using the model of phonon-assisted electron tunneling between the neutral traps and is supplemented by considering the space charge and charge carrier kinetics. Since the thermal and optical energies of the traps in the studied films are 1.6 eV and 3.2 eV, respectively, it is concluded that the traps are responsible for the charge transport in the Si—Si bonds. [ABSTRACT FROM AUTHOR]

The atomic structure of amorphous and crystalline hafnium oxide (Hf[O.sub.2]) films was examined using X-ray diffractometry and Hf edge X-ray absorption spectroscopy. The valence band of Hf[O.sub.2] consists of three subbands separated from each other by ionic gaps, the upper subband is formed by O 2p, Hf 4f and Hf 5d states and the intermediate subband is formed by O 2s and Hf 4f states.

Photoluminescence (PL) and electrical properties of boron doped zinc oxide (ZnO) thin films, deposited by metalorganic chemical vapour deposition on a glass substrate, were investigated. The effects of annealing in air, as well as the influence of the radiofrequency--plasma treatment in hydrogen atmosphere, on the PL and electrical conductivity of the ZnO films were studied. A correlation between photoluminescence and electrical properties during annealing was observed. Hydrogen plasma treatment causes an increase in the carrier mobility and concentration and results in a very intensive near band edge emission (NBE). It was found that defects responsible for the dramatic increase in the intensity of NBE band in the hydrogen-treated ZnO films are hydrogenrelated complexes formed near or at the surface of the samples. The intensity of NBE in hydrogentreated samples decreases after aging in the dark, and, conversely, the NBE intensity increases under UV light illumination. This effect is fully reversible and depends on the gas atmosphere during the UV exposure and subsequent aging. It was proposed that the NBE band in the ZnO films annealed in the air and treated in hydrogen plasma emerges due to O-H complexes forming at zinc vacancy sites, n(O-H)-VZn. [ABSTRACT FROM AUTHOR]

A new study investigates the effect of Fe and Zr ion implantation and subsequent high-current electron irradiation on the mechanical and chemical properties of Ti41-V41-Al18.

Research was conducted to examine the chemical composition and structure of Si3N4/thermal (native and wet) SiO2 interface in oxide-nitride-oxide structures using secondary ion mass spectroscopy, Auger electron spectroscopy and electron energy loss spectroscopy calculations. Si-Si defects were observed through numerical simulation of the Si-Si bond's electronic structure to act as either hole or electron traps. Results suggest the abnormally large electron and hole capturing at the interface.

The luminescence spectra of non-stoichiometric zirconium oxide film series with different oxygen vacancies' concentrations show the blue photoluminescence band centered near a 2.7 eV peak. There is a broad band at 5.2 eV in the luminescence excitation spectrum for blue emission. The ab-initio quantum-chemical calculation gives a peak in the optical absorption at 5.1 eV for the oxygen vacancy in cubic ZrO2. It was concluded that the 2.7 eV blue luminescence excited near 5.2 eV in a zirconium oxide film is associated with the oxygen vacancy. [ABSTRACT FROM AUTHOR]

Amorphous silicon oxide SiO2, silicon nitride Si3N4, and silicon oxynitride SiOxNy are three key dielectrics in silicon devices. Implementation of nitrided oxide (oxynitride SiOxNy) as a gate dielectric in metal-oxide-semiconductor field effect transistors has been shown to significantly improve the reliability and lifetime of devices. Also, amorphous oxynitride is used as a tunnel dielectric in nonvolatile flash memory devices. The present paper is devoted to the experimental and theoretical study of silicon oxynitride electronic structure. The ionic formula of crystalline Si2N2O is deduced from the first principles. Effective masses of charge carriers in Si2N2O are calculated and compared with experimental data on tunnel injection in amorphous SiNxOy samples. Also experimental x-ray absorption and emission spectra are compared with the theoretically calculated ones. [ABSTRACT FROM AUTHOR]

Electronic structure of oxygen vacancies in Ta2O5 have been studied theoretically by first-principles calculations and experimentally by x-ray photoelectron spectroscopy. Calculations of δ-Ta2O5 were performed using density functional theory within gradient-corrected approximation with the +U approach. Results indicate that the oxygen vacancy causes a defect level in the energy gap at 1.2 eV above the top of the valence band. To produce oxygen vacancies, amorphous films of Ta2O5 were bombarded with Ar+ ions. XPS results indicate that the Ar-ion bombardment leads to the generation of the oxygen vacancies in Ta2O5 that characterize the peak at 2 eV above the valence band. The calculated spectrum of crystalline δ-Ta2O5 demonstrates qualitative correspondence with the XPS spectrum of the amorphous Ta2O5 film after Ar-ion bombardment. [ABSTRACT FROM AUTHOR]

The Si 2p x ray photoelectron spectra of SiOx with a different composition of 0 ≤ x ≤ 2 have been studied experimentally and theoretically. The SiOx films were prepared by low-pressure chemical vapor deposition from SiH4 and N2O source at 750 °C. Neither random bonding nor random mixture models can adequately describe the structure of these compounds. The interpretation of the experimental results is discussed according to a large scale potential fluctuation due to the spatial variation of chemical composition in SiOx. [ABSTRACT FROM AUTHOR]

A theory for charge transport in dielectrics via tunneling between traps was developed. Unlike in the Frenkel model, in the present theory the traps are characterized with the thermal and optical ionization energies, and ionization proceeds by the multi-phonon mechanism. The theory predicts the tunneling between such traps to be a thermally stimulated process whose activation energy equals half to the difference between the optical and thermal ionization energies. The theory provides an adequate description to the experimental current-voltage characteristics of silicon-rich silicon nitride films. Such films have a high density of traps originating from the excess silicon present in the material, with charge transport proceeding as a charge carriers tunnel between closely spaced traps. [ABSTRACT FROM AUTHOR]

The nature of electron and hole trapping in silicon ion-implanted silicon oxide (SiO2) with a dose of 1016 cm-2 were studied using photoluminescence and electron spin resonance (ESR) measurements. We observed an ESR signal with g = 2.006 after hole and electron injections. These results unambiguously imply that the Si nanoclusters created by the high-dose Si implants are both electron and hole traps in the SiO2 films. [ABSTRACT FROM AUTHOR]

In the electron energy loss spectra for amorphous, atomic layer deposited (ALD) Al2O3 film, a peak at 6.4 eV was observed. First principle quantum chemical simulation shows that it relates to excitation of neutral oxygen vacancy in Al2O3. The 2.91 eV luminescence excited in a band near 6.0 eV in amorphous Al2O3 is similar to that in bulk crystals which is associated with neutral oxygen vacancy. Thus, the amorphous ALD Al2O3 film is oxygen deficient and the oxygen vacancy parameters are similar in crystalline and amorphous Al2O3. [ABSTRACT FROM AUTHOR]

A phonon-coupled trap model is proposed for trap-assisted injection mechanism in silicon-oxide-nitride-oxide-silicon (SONOS)/metal-nitride-oxide-silicon (MNOS) structures at low voltages. On the basis of this model, a theory of charge injection in SONOS/MNOS has been developed. Charge injection experimental data was fitted by this theory. Obtained trap parameters are close to those previously reported [K. A. Nasyrov et al., J. Appl. Phys. 96, 4293 (2004)], where the current dependence on temperature and electric field was investigated in MNOS. [ABSTRACT FROM AUTHOR]

A revised tight-binding Hamiltonian parametrization scheme for calculating the electronic structure of both covalent and ion-covalent solids is proposed. Unlike the conventional approaches, the present nonempirical calculation does not rely on any empirical parameter. We use the atomic properties of isolated atoms to construct the matrix elements. Results show that the predicted charge transfer in SiO2 and Si3N4, the bandgap energies of SiO2, Si3N4, and SiOxNy films, as well as the electron and hole barriers at the Si/SiO2, Si/Si3N4, and Si/SiOxNy interfaces are in good agreement with the experimental findings reported in literatures. [ABSTRACT FROM AUTHOR]

The charge transport in the amorphous Si3N4 is studied experimentally and theoretically. We have found, that widely accepted Frenkel model of the trap ionization gives the unphysical low value of the attempt to escape factor, and the enormously high value of the electron tunnel mass. Experimental data are well described by theory of the two-bands conduction and the phonon-assisted trap ionization in Si3N4. [ABSTRACT FROM AUTHOR]

Several first-principle quantum chemical simulations are conducted to determine the oxygen deficiency defects observed in the amorphous, atomic layer deposited [Al.sub.2][O.sub.3] films. The films are shown to be highly oxygen deficient and are found to exhibit similar oxygen vacancy parameters as the crystalline films.

In the electron energy loss spectra for amorphous, atomic layer deposited (ALD) Al2O3 film, a peak at 6.4 eV was observed. First principle quantum chemical simulation shows that it relates to excitation of neutral oxygen vacancy in Al2O3. The 2.91 eV luminescence excited in a band near 6.0 eV in amorphous Al2O3 is similar to that in bulk crystals which is associated with neutral oxygen vacancy. Thus, the amorphous ALD Al2O3 film is oxygen deficient and the oxygen vacancy parameters are similar in crystalline and amorphous Al2O3. [ABSTRACT FROM AUTHOR]