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We do inelastic electrical tunneling spectroscopy (IETS) to provide information concerning the vibrational and excitational modes present in silicon dioxide and phonon modes of the electrodes, and of silicon dioxide in metal-oxide-silicon tunnel junction. We analyze the phonon spectra coming from different parts of the metal-oxide-semiconductor (MOS) junction: the aluminum gate, the SiO2 ultrathin film, and the silicon substrate. We compare the phonon modes for the (100) and (111) silicon orientations. We show that IETS can reveal the modifications of Si-SiO2 interface induced by electrical stresses. After a constant voltage stress, the silicon longitudinal phonon modes are significantly shifted in energy, while the transversal phonon modes stay unaffected. Interface healing after annealing is also observed by IETS. These features make IETS a useful tool for MOS reliability studies.

We describe an easy to build inelastic electron tunneling spectrometer, controlled by a computer, to analyze and characterize metal–oxide–semiconductor (MOS) devices. The method, material, and circuit are also described. Typical inelastic electron tunneling spectra obtained from a MOS tunnel junction with various degrees of nonlinear conductance–voltage behavior are presented. Our results suggest that such a spectrometer has appropriate resolution (4 mV of full width half maximum) and suitable signal-to-noise ratio to clearly identify the electrode and insulator vibrational modes. Results are reported on aluminum gate 2.1 nm thick oxide devices fabricated on n-type (111) silicon substrates.

The inelastic electron tunnelling spectroscopy (IETS) technique is performed to provide information concerning the vibrational and excitational modes present in MOS tunnelling junctions (molecular species present in silicon dioxide and phonon modes of both silicon substrate and silicon dioxide). The first relevant structures of silicon substrate phonons are investigated in both (1 1 1) and (1 0 0) orientations for the first time. The separated peaks obtained after deconvolution are identified and compared with literature data for both silicon orientations. The IET spectrum of ultra-thin silicon dioxide is also obtained though this spectrum is more difficult to detect. Finally, two different technologies of manufacturing MOS tunnelling junctions are compared.

We report on inelastic electron tunneling spectroscopy of a tunneling metal–oxide–semiconductor (MOS) device over an extended energy range compared to previous results. We have clearly observed the vibrations of the hydrogen-passivated (111)Si Pb center in this extended energy range. The assignment of this mode has been confirmed by a comparison with infrared experiments. Capabilities and limitations of the technique to detect and observe molecular vibrations in tunneling MOS devices are discussed.

Fowler–Nordheim current in Si-poly (n+)-SiO2–Si(p) structures, with an oxide thickness varying between 3 and 12 nm, has been measured and numerically computed with the exact electric field in the oxide, the field dependence of the barrier shape with the image force, and the temperature effects. The fit of the experimental data leads to an accurate determination of the electron affinity difference and the barrier height at the emitting Si–poly (n+)-gate-electrode–oxide interface. The evolution of these two parameters with temperature is discussed in relation with the oxide thickness.

The Fowler–Nordheim (FN) current in Si-poly (n + )-SiO 2 –Si(p) structures was measured and computed numerically using the complete integral equation taking into account the temperature, the flat-band voltage changes, the effective masses and the field dependence of the barrier shape with the image force. The fit of the experimental data allows an accurate determination of the electron affinity difference ( Φ ) and the barrier height ( Φ B ) at the emitting Si-poly(n + ) gate electrode–oxide interface. The correlation between the temperature changes of these two parameters and the oxide thickness is discussed.

The variations with temperature of the Fowler–Nordheim (FN) emission in metal–oxide–semiconductor structures when the injecting electrode is the degenerate polysilicon gate (n+) are investigated. The temperature dependence of the electron affinity difference Φ between Si and SiO2 and of the barrier height Φb for three oxide thicknesses (5, 7, and 12 nm) are analyzed. The results are numerically derived from the exact integral expression of the FN current as functions of temperature varying from 25 to 300 °C. The variation with temperature of both the obtained Φ and dΦ/dT parameters at the polysilicon (n+)–oxide barrier are discussed with respect to the literature data.

Tunneling Fowler–Nordheim bidirectional electron injections were performed on a metal–oxide–silicon capacitor under constant voltage, and the study of generated defects behavior was investigated. It was found that defects generated within the oxide are of the same physical nature and are mainly composed of neutral traps. The charge and discharge of these traps depend on the oxide field polarity. At the oxide–silicon interface, the saturation of interface state generation is maintained by the alternate change of the stress field polarity. This saturation is linked to the Si−δ–H+δ or other Si−δ–A+δ polar bonds at the silicon/oxide interface.

Irradiation effects on the electrical characteristics under high field stress of nitrided and non-nitrided very thin silicon oxide films are studied. The generation of new electron traps during constant current stress is increased for irradiated samples. This enhancement is more significant for pure silicon dioxide when compared to nitrided oxide. Further, the correlation between charge to breakdown and traps generation rate during constant current injection is verified and remains valid after irradiation.

This work presents polarity effects during Fowler-Nordheim electric field stress on defect generation in thin silicon dioxide films and at the interface with the silicon. The results show a dissymmetry on interface state kinetic generation and the presence of a critical injected fluence at which the dissymmetry is reversed. For injected fluences lower than this critical charge, the density of interface states created under positive gate bias is higher than that generated under negative bias, and if the injected charge is higher than the critical fluence the dissymmetry is reserved. However, the net oxide positive charge generated under positive bias is always lower than that created under negative bias.

We have compared the charge created in p‐metal–oxide–semiconductor capacitors by Fowler–Nordheim injection from the gate and from the substrate. We have shown that an injection from the gate creates a negative charge, trapped holes, and positively charged slow states whereas an injection from the substrate creates a negative charge, slow states, and amphoteric neutral traps; once charged these neutral traps are discharged irreversibly, as are the trapped holes, by an appropriate gate bias. We have observed that the discharge of the trapped holes, and the charge or discharge of the slow states, obey the same general law, but the time response of the trapped holes is always shorter than the time response of the slow states. This general law is equivalent to the so‐called ‘‘universal law,’’ which is the law which describes the time dependence of current observed in any dielectric in response to a step‐function field.

Fowler-Nordheim tunneling injections were performed, from the gate, or from the substrate, in P-type metal oxide semiconductor capacitors with polysilicon gates in both wet and dry oxides. When the injection was from the gate, trapped holes, as well as negative and anomalous positive charges were created and it was possible to determine their amplitude and their centroid. When the injection was from the substrate, only negative and anomalous positive charges were created, but the determination of the centroids was not always possible since the positive charge appears to be located at both interfaces.

The oxide positive charge and the interface-state formation caused by a negative gate bias in a polycrystalline silicon gate-oxide-semiconductor capacitor versus injecting temperature in the range of 77–400 K is studied. It is found that the generation of both interface-states and oxide charge is temperature independent which indicates that the motion of each mobile species (as the hydrogen-related species) must be excluded. The formation of interface-states is linked to the break of SiSi or SiO distorted bonds at the Si SiO 2 interface, and the generation of the oxide positive charge to the electron-emission from pre-existing or created neutral traps.

The influence of X-ray irradiation on the conduction properties and breakdown of silica layers less than 10 nm thick has been investigated. It has been found that these properties are not drastically affected, and that the X-ray irradiation induces a decrease of the defectiveness, as for much thicker layers.

The potential distribution across n+ polycristalline silicon (poly-Si)/SiO2/Si(p) structures, with an oxide layer thinner than 4 nm, was determined using a full quantum self-consistent model. When applied to capacitance–voltage measurements, it allows an accurate determination of the oxide thickness tox to be made. When applied to current–voltage measurements, in the Fowler–Nordheim regime, it leads to an accurate determination of the barrier height Φ at the interface between the emitting poly-Si gate electrode and the oxide, over a temperature range 20–250 °C. The results show a constant Φ(0 K) for 3 nm

The creation of defects into a thin gate oxide (11 nm) of polycrystalline silicon‐oxide‐semiconductor capacitors by electron injection Fowler–Nordheim effect, their electric nature, and their behavior when stressed samples are submitted to a white‐light illumination in the inversion regime are studied. It is shown that low‐electron‐injected fluences cause creation of positive charges and that high fluences generate negative charges in the bulk of the oxide. Current‐voltage characteristics have been performed in the accumulation and the inversion regimes before and after electron injection. These characteristics show a very weak shift and a small distortion which seem to indicate that the negative charges are localized close to the injecting electrode and the positive charges near to the Si/SiO2 interface. These positive charges are annihilated by light illumination without interface‐state generation when stressed samples are biased in the inversion regime. Interface states do not show any saturation and t...

The temperature dependence (in the range 100–450 K) of the generation of fast interface states at the Si–SiO2 interface by high electric field stress in metal–oxide‐semiconductor capacitors when electrons are injected by Fowler–Nordheim tunneling from the Si substrate (n type Si, with a positively biased gate) and from the gate (p type Si, with a negatively biased gate) was analyzed. In both cases, two different temperature regimes can be distinguished, which correspond to two mechanisms responsible for the creation of fast interface states. At stress temperature Ts larger than 180 K, a temperature‐activated regime is shown to be consistent with a diffusion of hydrogen‐related species, while for Ts

The possibilities of tunneling spectroscopy in metal-oxide-degenerate silicon with a very thin oxide layer have been studied at low temperature by measuring the first and second derivatives of the current-voltage characteristics. Silicon phonon structures are easily detectable whereas high level features induced by molecular vibrations are hardly seen. The aim of this paper is to show that the main difficulty lies in the metal-oxide-semiconductor junction band structure itself.

A MgO single crystal partly coated with a thin layer of Ag was irradiated with incident electrons while the time evolution of the surface potential and specimen current were recorded. A zero surface potential, Vs, is measured when the uncoated part of the specimen is irradiated, while the potential is very negative on the coated part for primary beam energies in the 2–5 keV range. The results invalidate the usual approach which uses a theoretical total yield curve for evaluating the sign of the surface potential as well as the use of an ohm law Vs = RIs for correlating the surface potential Vs and the specimen current Is. Explanations of the observed phenomena are suggested and their correlation with the secondary electron emission of insulators is indicated. One surprising result is the possibility of injecting (nonohmic) current densities of 1 mA/mm2 or greater into insulators having electrical resistivities of 1015 Ω cm.

IETS (Inelastic Electron Tunnelling Spectroscopy) technique was used in Metal-Oxide-Silicon (MOS) tunnel junctions to provide information concerning the vibrational and excitational modes. In this work, we use the IETS method to investigate electron-molecular vibration coupling in SAMs (Self Assembled Monolayer) using the MOS tunnel junctions as a test-bed.

We studied the influence of the end group of the alkylsilane molecule used in Self Assembled Monolayer (SAM) in Silicon/SAM/Metal junctions. By Inelastic Electron Tunneling spectroscopy (IETS), we showed the formation of a covalent bond between the molecules and the gold electrode in the case of a thiol terminated alkylsilane. By electrical characterizations, we demonstrated that the thiol group at the interface avoids diffusion of gold into the molecule even for a 3 carbons chain. For this short molecule, we observed pure tunnel conduction with barrier height at the monolayer/Si and monolayer/Au interfaces found to be respectively 2.14 and 2.56 eV. These values were obtained using Simmons equation with an effective mass parameter m* = 0.16m e (m e = mass of the electron).This extends the demonstration of the excellent tunnel dielectric behavior of these organic monolayers down to 3 carbon atoms with a thiol/Au bond at the interface.

The paper deals with porous Si (PSi) samples, prepared with different parameters (substrate, current density, solution, etc.) of anodization and anodic oxidation. The porosity of samples varied between 36 and 78%, their thickness was 1–5 p.m. The samples were studied in six laboratories using complementary methods. The spectra of elastic reflection coefficients r e (E p ) are characteristic of the composition and they are affected by the structure of the surface layer. They were measured with a retarding field analyser using spectrometer correction and deduced from the elastic peak versus E p primary energy. The r e (E p ) showed a dramatic decrease in the 50–100 eV range with H adatoms on the surface, produced by HF treatment. It is caused by attenuation and multiple elastic reflections of electrons on the porous surface with H adatoms. An oxidized sample showed a contrary effect, which can be explained by the elastic reflection cross-sections of Si and O in this low energy range. Valence band XPS spectra were measured with a KRATOS XSAM 800 analyser. They showed changes with HF treatment and porous structure. To avoid difficulties with STM due to the oxide, the surface topography was mapped by atomic force microscopy, resulting in 0.3–0.9 nm roughness on samples of 36% porosity.

In this paper, the influence of gamma irradiation (unbiased devices) on the electrical properties of Metal-Oxide-Semiconductor (MOS) devices with an ultra-thin silica layer N/sub 2/O-nitrided or not is investigated. Mainly electron trapping, defects generation and breakdown during electrical stress are studied.

From elementary calculations of the Auger signal intensities from a specimen at two different take-off angles, O 1 and O 2 , it is shown that the simultaneous acquisition of these spectra allows homogeneous alloys ans stratified samples to be identified and also the presence of topographic effects. The preliminary results confirm the potential of multiple angular detection Auger electron spectroscopy (MADAES) that can be developed by using only one analyser of cylindrical mirror type. Further developments are also indicated

Fowler–Nordheim (F.N.) tunneling of electrons from the gate into thin thermally grown SiO2 under high electrical field stress has been performed with polycrystalline Si‐SiO2‐Si capacitors and relaxation of both interface state densities and flat‐band voltage investigated during several months after F.N. stress at room temperature. It has been found that the relaxation behavior of surface states and positive charge densities follow fractional power laws in time.

High electrical stresses have been applied to n -MOS capacitors prepared following two thermal oxidation methods. The increase of the interface state density was investigated by means of a conductance method and incidentally by a quasi-static method. A threshold effect, possibly related to a Fowler-Nordheim injection, has been found in the increase of this density versus field stress. At high field stresses, a second conductance peak has been observed, which can be explained in terms of new interface states, rather than lateral nonuniformities.

Tunnelling phenomena were studied in two kinds of specimens: samples A, essentially metal—silicon junctions, featured a thin silicon oxide transition layer; samples B were prepared by the anodization of silicon in pure water. I, dI/dV and d2I/dV2vs. V curves were obtained at liquid helium temperature. For both specimens, the general shapes of the curves were in agreement with the theoretical prediction. Phonon fine structure was obtained. Moreover, for samples A, a zero-bias anomaly phenomenon, indicating the presence of metal particles in the oxide, as well as other structures, due to traps, were observed. The absence of such structures and of a zero-bias anomaly for samples B and the appearance of phonon structures, in spite of the considerably smaller amount of doping, are indications of a good quality oxide. This was in accordance with capacitance measurements made on thicker oxide obtained by the same process. These experiments show that inelastic electron tunnelling spectroscopy can be used as a valuable tool for the study of very thin silicon oxide layers in electron devices.

MNS capacitors were submitted to a series of alternating voltage pulses, and measurements were performed at different stages of this cycling. The interface state parameters at the SiSi 3 N 4 interface were evaluated using the conductance method; the surface potential ψ S was obtained from a measurement of the high-frequency capacitance. Experimental results are explained by the formation, during cycling, of new fast surface states located at the SiSi 3 N 4 interface.

We review some of our recent experimental results on charge transport in organic nanostructures such as self-assembled monolayer and monolayers of organic semiconductors. We describe a molecular rectifying junction made from a sequential self-assembly on silicon. These devices exhibit a marked current-voltage rectification behavior due to resonant transport between the Si conduction band and the π molecule highest occupied molecular orbital of the π molecule. We discuss the role of metal Fermi level pinning in the current-voltage behavior of these molecular junctions. We also discuss some recent insights on the inelastic electron tunneling behavior of Si/alkyl chain/metal junctions.

An insulating layer is produced on aluminum by glow discharge in CF4. This substrate, used as the insulator of metal-insulator-metal diodes is characterized by Inelastic Electron Tunneling Spectroscopy as an aluminum trifluoride AlF3. The adsorption of ammonia, benzylamine. formic and propiolic acid on this substrate is investigated. A comparison between spectra of samples obtained on this insulator and on alumina for the same dopant molecules shows significant differences which are interpreted as revealing an enhanced Lewis acidity of AlF3 relative to Al2O3, determined — at least in part — by an enhanced electronegativity of surface Al+ cations of AlF3.