Abstract: A high-mobility field-effect transistor, includes a stack along a Z axis, deposited on a substrate and comprising a buffer layer, a barrier layer, a heterojunction between the buffer layer and the barrier layer, and a two-dimensional electron gas localized in an XY plane perpendicular to the axis Z and in the vicinity of the heterojunction, a source, a drain, and a gate deposited on an upper face of the barrier layer, between the source and the drain, a first dielectric layer having a relative permittivity ?r and a thickness e which are such that: 0.5 nm?e/?r?2 nm, a metal pad arranged between the gate and the drain and deposited on the first dielectric layer, the metal pad being electrically connected to the gate.

Abstract: A transistor comprises a stack of semiconductor materials including, in particular, a first sub-layer, carefully arranged and with a specific thickness, splitting the buffer layer into two portions and including a third material so that the difference in the piezoelectric and spontaneous polarisation coefficients between the material of the buffer layer and the third material induces, at a first interface between the first portion of the buffer layer and the first sub-layer, a first fixed surface electric charge generating an electrical field directed along the axis z so as to follow the two-dimensional gas to be contained in the channel.

Abstract: A stack along a z-axis for a high-electron-mobility field-effect transistor, comprises: a buffer layer comprising a first semiconductor material comprising a binary, ternary or quaternary nitride compound having a first bandgap, a barrier layer comprising a second semiconductor material comprising a binary, ternary or quaternary nitride compound and having a second bandgap, the second bandgap wider than the first bandgap, a heterojunction between the buffer and barrier layers and, a two-dimensional electron gas located in an XY plane perpendicular to the z-axis and in the vicinity of the heterojunction wherein: the buffer layer comprises a zone comprising fixed negative charges of density per unit volume higher than or equal to 1017 cm?3, the zone having a thickness smaller than or equal to 200 nm, the product of multiplication of the density per unit volume of fixed negative charges by the thickness of the zone between 1012 cm?2 and 3.1013 cm?2.

Abstract: A field-effect transistor comprising a stack of semiconductor materials, the upper face of the stack being covered with a passivation layer comprises two sub-layers: a first sub-layer extending over a second zone of low intensity comprising a first material with electric breakdown field Ecl1, the charge of the first sub-layer being strictly less than the charge of the upper face of the stack, a second sub-layer extending over a first zone of high intensity and covering the first sub-layer, the second sub-layer comprising a second material with electrical breakdown field Ecl2 strictly greater than Ecl1.

Abstract: A stack along a z-axis for a high-electron-mobility field-effect transistor, comprises: a buffer layer comprising a first semiconductor material comprising a binary, ternary or quaternary nitride compound having a first bandgap, a barrier layer comprising a second semiconductor material comprising a binary, ternary or quaternary nitride compound and having a second bandgap, the second bandgap wider than the first bandgap, a heterojunction between the buffer and barrier layers and, a two-dimensional electron gas located in an XY plane perpendicular to the z-axis and in the vicinity of the heterojunction wherein: the buffer layer comprises a zone comprising fixed negative charges of density per unit volume higher than or equal to 1017 cm?3, the zone having a thickness smaller than or equal to 200 nm, the product of multiplication of the density per unit volume of fixed negative charges by the thickness of the zone between 1012 cm?2 and 3.1013 cm?2.

Abstract: A semiconductor device for electron emission in a vacuum comprises a stack of two or more semi-conductor layers of N and P type according to sequence N/(P)/N forming a juxtaposition of two head-to-tail NP junctions, in materials belonging to the III-N family, two adjacent layers forming an interface. The semiconductor materials of the layers of the stack close to the vacuum, where the electrons reach a high energy, have a band gap Eg>c/2, where c is the electron affinity of the semiconductor material, the P-type semiconductor layer being obtained partially or completely, by doping impurities of acceptor type or by piezoelectric effect to exhibit a negative fixed charge in any interface between the layers, a positive bias potential applied to the stack supplying, to a fraction of electrons circulating in the stack, the energy needed for emission in the vacuum by an emissive zone of an output layer.

Abstract: A semiconductor device for electron emission in a vacuum comprises a stack of two or more semi-conductor layers of N and P type according to sequence N/(P)/N forming a juxtaposition of two head-to-tail NP junctions, in materials belonging to the III-N family, two adjacent layers forming an interface. The semiconductor materials of the layers of the stack close to the vacuum, where the electrons reach a high energy, have a band gap Eg>c/2, where c is the electron affinity of the semiconductor material, the P-type semiconductor layer being obtained partially or completely, by doping impurities of acceptor type or by piezoelectric effect to exhibit a negative fixed charge in any interface between the layers, a positive bias potential applied to the stack supplying, to a fraction of electrons circulating in the stack, the energy needed for emission in the vacuum by an emissive zone of an output layer.

Abstract: The disclosure relates to a magneto-optical reading device for multi-track magnetic tapes, including a flat large incident beam directed onto the active part of a magneto-optical read head and reflected by this head onto an array of sensors, characterized in that it includes a correction device able to move the zone of incidence of the beam on the read head in order to keep the beam optimally positioned on the active part of the read head as the latter suffers progressive wear. The invention increases the useful working life of such a reading device.

Abstract: A magnetooptic read device in which the figure of merit is optimized mainly by the setting of the incident light polarizer. The component of the incident wave pumps the magnetooptic transducer. The component of the incident wave amplifies the variations in the magnetooptic wave and generates a reflected wave of approximately linear polarization.

Abstract: A magnetooptic read head including a magnetooptic transducer with a multilayer structure with at least one thin magnetic layer with a magnetooptic effect, at least one layer made of nonmagnetic material and having a predetermined wear coefficient, and a layer with good magnetic permeability for closing a magnetic circuit. The layer with good magnetic permeability includes alternating first sublayers made of a magnetic material with good magnetic permeability and second sublayers made of a material having a wear coefficient substantially equivalent to the wear coefficient of the layer made of a nonmagnetic material.

Abstract: A magnetooptic read device in which the figure of merit is optimized mainly by the setting of the incident light polarizer. The component S of the incident wave pumps the magnetooptic transducer. The component P of the incident wave amplifies the variations in the magnetooptic wave and generates a reflected wave of approximately linear polarization.

Abstract: A process for producing magnetoresistive transducers, using microlithographic techniques, where the transducers have magnetic metallic multilayers deposited by sputtering or by molecular beam epitaxy, and forming columns whose side walls will be covered with an insulation and whose tops will be free of this insulation, such that a current is able to flow in the magnetoresistive transducers perpendicular to the plane of the layers so as to exploit a phenomenon of perpendicular giant magnetoresistance. This process includes a step of producing, on one surface of a substrate, a stack including a first conductive layer in contact with a substrate and successive magnetic layers and non-magnetic metallic layers constituting a magnetic metallic multilayer in contact with the conductive layer.