Polymerlike hydrogenated amorphous carbon $(a\ensuremath{-}\mathrm{C}:\mathrm{H})$ films have been deposited by plasma CVD at low temperature and pressure. Vibrational properties investigated in situ infrared ellipsometry as a function of film thickness. Hydrogen distribution within the has changed varying ion energy impinging on surface. $\mathrm{C}\mathrm{---}\mathrm{H}$ stretching bending modes analyzed self-bias ${(V}_{\mathrm{bias}})$ terms frequency, bandwidth, intensity. Absorption...

High sensitivity, high-energy resolution, and the capability to obtain data in situ make ellipsometry a useful tool for addressing number of problems thin-film deposition processes. Dielectric functions ε̃=ε1−i ε2 glow-discharge-produced microcrystalline silicon films (μc-Si) are determined by using spectroscopic (SE). spectra present shoulder near 4.2 eV which corresponds E2 optical transition observed crystalline silicon. This peak is not amorphous spectra. c-Si described as mixture phase,...

Localized electronic states corresponding to \ensuremath{\pi} electrons in hydrogenated amorphous carbon have been investigated using photoluminescence (PL) and optical-absorption spectroscopies. Carbon films contain \ensuremath{\pi}-bonded ``grains'' with different configurations which spatially confine photogenerated electron-hole pairs. A model of PL $a\ensuremath{-}\mathrm{C}:\mathrm{H},$ including excitonlike radiative recombination electron tunneling nonradiative acceptor centers at...

In the present study, we report hydrogen content estimation of hydrogenated amorphous carbon (a-C:H) films using visible Raman spectroscopy in a fast and nondestructive way. Hydrogenated diamondlike were deposited by plasma enhanced chemical vapor deposition, beam source, integrated distributed electron cyclotron resonance techniques. Methane acetylene used as source gases resulting different sp2∕sp3 fraction. Ultraviolet-visible (UV-Vis) spectroscopic ellipsometry (1.5–5eV) well UV-Vis...

Hydrogenated amorphous carbon and nitride films (a-C1−xNx:H) have been synthesized from methane, acetylene, or acetylene–nitrogen precursor gases using a high density electron cyclotron resonance plasma. The deposition etching rates, along with the film stoichiometry, density, Raman signature of sp2 phase, optical transport properties, studied as function plasma parameters (microwave power negative bias substrate). While low-density H-rich grown methane for ion energies up to 200 eV,...

In order to understand the radiative recombination mechanisms in silicon oxides, photoluminescence properties (PL) of H-rich amorphous oxide thin films grown a dual-plasma chemical vapor deposition reactor have been related number stoichiometry and structure characterizations (x-ray photoelectron spectroscopy, vibrational gas evolution studies). The visible at room temperature from a-SiOx:H matrixes with different compositions, including bonding environments for H atoms, has studied...

Abstract A numerical hopping model is developed to investigate the temperature dependence of electrical conductivity in a distribution localized states. An exponential energy density-of-states (DOS) (N 0/E 0)exp(E/E 0) assumed, together with high DOS value (1 × 1018-1 1021cm−3 eV−1) at Fermi level. The low-field dc dominated by subset states centred mean transport E t located well above t; both and width (ΔE ≫ kT) increase increasing temperature, range 50–500 K. It found that effective...

The plasma deposition of nanocrystalline silicon thin films is usually performed under a high flux atomic hydrogen and hydrogenated chemical species. growth mechanisms are investigated using the layer-by-layer dense silicon, obtained at 250 °C by alternating SiH4 H2 plasmas. In steady state, minimum exposure time to necessary recrystallize amorphous top layer (10–85 Å). It shown that this critical determined diffusion some mobile H through a-Si:H layer. recrystallization discussed in...

In this paper the role of nitrogen bonding regime and presence lone-pair electrons due to atoms on optical properties disordered hydrogenated carbon nitride $(a\ensuremath{-}\mathrm{C}\mathrm{N}:\mathrm{H})$ thin films grown by reactive sputtering are studied. Evidence is given for existence a variable amount mixing between atom states \ensuremath{\pi} electronic in different samples. It proved that such favors stabilization lone pairs. By properly analyzing local disorder mixing, an...

Octahedral molybdenum cluster cores [Mo6I8]4+ have been attached in apical positions to p- and n-type Si(111) surfaces through complexation with a pyridine-terminated organic monolayer (2 × 1014 cm−2), which was previously covalently bound hydrogen-terminated Si(111). This grafting procedure resulted about 4 nm thick Mo6-terminated layer. Similar XPS results were found for samples, suggesting that the efficiency composition of resulting layers do not depend significantly on doping type...

Nitrogen-doped hydrogenated amorphous carbon, films, were synthesized by microwave electron cyclotron resonance plasma-enhanced chemical vapor deposition, using as precursors. Such with thickness in the range of a few tens nanometers, very smooth, and pinhole free, appear electrode materials reactivity effective window potential similar to those boron-doped polycrystalline diamond or nitrogen-doped diamond. These grown on Si Ti substrates, investigated regard their electrochemical toward...

The electronic properties of redox-active transition metal clusters (Re6Se8) covalently immobilized on modified Si(111) surfaces through linear alkyl spacers have been studied as a function the cluster coverage (1 × 1013−6 1013 cm−2). latter is controlled by using Si(111)/H dense mixed alkyl/acid-terminated monolayers with variable fraction acid grafting sites from 5 to 100% in solution. Quantitative X-ray photoemission analysis, spectroscopic ellipsometry, and scanning tunnelling microscopy...

Abstract In order to investigate the localized electronic states in hydrogenated amorphous carbon (a-C : H) films, temperature and electric field dependences of current density have been measured low-field coplanar (Al/a-C H/Al) high-field transverse (TiW/a-C H/TiW) geometries. The very-low-field conductivity σ = σ00 exp[−(T 0/T)1/4] reveals a band-tail hopping transport mechanism an Ohmic regime (at least for films above 20 nm thickness) while, values F > 4 × 103 V cm−1, different behaviour...

The covalent attachment of ester-, pyridine-, and ferrocene-functionalized organic layers to amorphous carbon surfaces, grown by graphite sputtering in Ar−H2 mixtures, is reported. surface modification based on a low temperature (160 °C) liquid-phase process. Thermally assisted grafting linear alkenes investigated means X-ray photoelectron spectroscopy (XPS), atomic force microscopy, contact angle measurements. beneficial role oxygen removal argon ion or thermal treatment prior the ester...

Polymer-like hydrogenated amorphous carbon (a-C:H) films have been grown in a dual-plasma [radio frequency (rf)–microwave (MW)] reactor using butane as precursor and different mixtures (H2–Ar or He–Ar) the MW plasma order to vary atomic hydrogen flux impinging on growing film. Decreasing rf power (i.e., energy of ion bombardment a-C:H) increasing H atom both result wide band gap H-rich polymer-like a-C:H network. Nuclear techniques combined with UV-visible ellipsometry determine...

Our previous modeling of hopping in localized bandtails has improved the description electrical transport amorphous carbon films and elemental semiconductors. This model is further developed to understand role wavefunction localization radius γ—1 density states (DOS) distribution N(E) on T dependence conductivity thermopower disordered solids. Using values parameter LP = N(EF) γ—3 range from 10—4 1 eV—1, our simulations show that: (i) The assumption extremely low made works often irrelevant...

I n situ spectroscopic ellipsometry is used to reveal the structural changes that occur in initial stages of growth microcrystalline silicon (μc-Si) deposited by glow discharge decomposition a (SiH4,H2) mixture on silica substrates. In first step, real time measurements can be described following nucleation model: stable nuclei are created, with an average distance between them estimated ∼100 Å, followed three-dimensional crystalline islands. second step interfacial component composed...