Comprehensive characterization of interface and oxide states in metal/oxide/semiconductor capacitors by pulsed mode capacitance and differential isothermal capacitance spectroscopy

6 pagesInternational audienceIn metal/insulator/semi-conductor structures, capacitance-voltage characteristics and capacitance or voltage transients can be measured in different conditions, which are described and implemented. Each method contains information about charges which are accommodated, captured or emitted by energy levels or bands at interface and inside the oxide. Pulsed capacitance measurements and differential isothermal procedures are analysed and performed. Calibration of the energy scale from the interface potential as a function of the applied voltage and extraction of the interface state spectra and characteristic response times independently are possible with the help of signal processing by Fourier transform of transients at one or few selected temperatures. Different trap filling conditions may help to discriminate between interface and oxide states. These methods are applied to Al/SrTiO3/Si capacitors as an example

Interplay of bonding and electronic properties at diamond interfaces

International audiencePotential discontinuities and spatial profiles govern the electronic properties of elementary devices like Schottky diodes and metal/insulator/semiconductor (MOS) structures. At interfaces between oxygenated diamond and other materials, two situations are examined: (1) Zr Schottky contact; (2) MOS capacitors, mainly using Al2O3 as an insulator.In the first case, we give two experimental evidences of potential barrier inhomogeneities and/or domains, which almost vanish after annealing at 450°C, with a simultaneous decrease of the homogeneous barrier height of 1.4 eV, analogous to the change in electronic affinity when the oxygen terminations disappear from the surface. This evolution is the same for 4 other metals. The model able to comply with these experimental facts relies on the Mott-Schottky linear relationship which links the barrier height and the electronic affinity at a zero order of approximation, and on a correction term proportional to the charge transfer in interface bonds. This last term is able to justify the reverted slope observed regarding the dependence of the barrier height on the metal work function.In the second case, a capacitance measurement method is developed in order to show the projected interface states density and Fermi level pinning at the Al2O3 /oxygenated diamond interface of MOS capacitors. Reasons for these results, based on bonding between carbon, adsorbates and insulator atoms, and possible routes to free the interface from this Fermi level pinning are discussed

Oxygen vacancy and EC − 1 eV electron trap in ZnO

International audienceFourier transform deep level transient spectroscopy has been performed between 80 and 550 Kin five n-type ZnO samples grown by different techniques. The capture cross section andionization energy of four electron traps have been deduced from Arrhenius diagrams. A trap1 eV below the conduction band edge is systematically observed in the five samples with alarge apparent capture cross section for electrons (1.6 ± 0.4 × 10−13 cm2) indicating a donorcharacter. The assignment of this deep level to the oxygen vacancy is discussed on the basis ofavailable theoretical predictions

Zr/oxidized diamond interface for high power Schottky diodes

International audienceHigh forward current density of 103 A/cm2 (at 6 V) and a breakdown field larger than 7.7 MV/cm for diamond diodes with a pseudo-vertical architecture, are demonstrated. The power figure of merit is above 244 MW/cm2 and the relative standard deviation of the reverse current density over 83 diodes is 10% with a mean value of 10 9 A/cm2. These results are obtained with zirconium as Schottky contacts on the oxygenated (100) oriented surface of a stack comprising an optimized lightly boron doped diamond layer on a heavily boron doped one, epitaxially grown on a Ib substrate. The origin of such performances are discussed

Hole injection contribution to transport mechanisms in metal/p− /p++and metal/oxide/p− /p++ diamond structures

International audienceHeterostructures such as Schottky diodes and metal/oxide/semiconductor structures are the building blocks of diamond electronic devices. They are able to carry large current densities, up to several kA/cm$^2$, if a heavily boron doped layer (p$^{++}$) is included in the semiconducting stack, thus affording a metallic reservoir of mobile holes close to the lightly doped layer (p$^{-}$). In this work, hole injection effects are evidenced experimentally in the two previously mentioned devices and also simulated numerically. Although the potential barrier height at metal/semiconductor interfaces is a fundamental parameter, a more general approach consists in defining the current density from the product of an effective velocity and carrier concentration at interface. In accordance with experimental results, such a view permits to describe both depletion and accumulation regimes, which indeed can exist at the metallic or oxide interface, and to take into account the increase of the hole concentration above the thermal equilibrium one in the p$^{-}$ layer. The lower the temperature, the larger is this second effect. For sufficiently thin p$^{-}$ layers, typically below 2~$\mu$m, this effect frees device operation from the limitation due to incomplete ionization of acceptors and allows a strong decrease of the specific resistance and forward losses while preserving breakdown voltages in the range 1.4 to 2 kV

Interplay of bonding and electronic properties at diamond interfaces

International audiencePotential discontinuities and spatial profiles govern the electronic properties of elementary devices like Schottky diodes and metal/insulator/semiconductor (MOS) structures. At interfaces between oxygenated diamond and other materials, two situations are examined: (1) Zr Schottky contact; (2) MOS capacitors, mainly using Al2O3 as an insulator.In the first case, we give two experimental evidences of potential barrier inhomogeneities and/or domains, which almost vanish after annealing at 450°C, with a simultaneous decrease of the homogeneous barrier height of 1.4 eV, analogous to the change in electronic affinity when the oxygen terminations disappear from the surface. This evolution is the same for 4 other metals. The model able to comply with these experimental facts relies on the Mott-Schottky linear relationship which links the barrier height and the electronic affinity at a zero order of approximation, and on a correction term proportional to the charge transfer in interface bonds. This last term is able to justify the reverted slope observed regarding the dependence of the barrier height on the metal work function.In the second case, a capacitance measurement method is developed in order to show the projected interface states density and Fermi level pinning at the Al2O3 /oxygenated diamond interface of MOS capacitors. Reasons for these results, based on bonding between carbon, adsorbates and insulator atoms, and possible routes to free the interface from this Fermi level pinning are discussed

Recent progress of diamond device toward power application

International audienceThe state of the art of the Institut Néel research activity in the field of diamond power devices will be described and discussed. The active layers of the device are based on boron-doped monocristalline (100) diamond (with doping level varying between 1014 to 1021 cm-3) grown on Ib high temperature high pressure (HPHT) diamond substrate. The progresses done on diamond/metal interface, diamond/dielectric interface, or sharp gradient doping, permit recently the fabrication of original structures and devices, which will be detailed here (Schottky diode, boron doped δ-FET and MOS capacitance)

Philippe Gonnard. Les Origines de la légende napoléonnienne. L'œuvre historique de Napoléon à Sainte-Hélène, 1906

Muret Pierre. Philippe Gonnard. Les Origines de la légende napoléonnienne. L'œuvre historique de Napoléon à Sainte-Hélène, 1906. In: Revue d'histoire moderne et contemporaine, tome 8 N°8,1906. pp. 610-617

H. Thirion. Madame de Prie (1698-1727), 1905

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La Vie politique dans les Deux Mondes. Troisième année et quatrième année, 1910 et 1911

Muret Pierre. La Vie politique dans les Deux Mondes. Troisième année et quatrième année, 1910 et 1911. In: Revue d'histoire moderne et contemporaine, tome 17 N°1, Janvier-Février 1912. pp. 78-79