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 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: An electronic HEMT transistor structure comprises a heterojunction formed from a first layer, called a buffer layer, of a first wide bandgap semiconductor material, and a second layer of a second wide bandgap semiconductor material, with a bandgap width EG2 larger than that Eg1 of the first material, and a two-dimensional electron gas flowing in a channel confined in the first layer under the interface of the heterojunction. The first layer furthermore comprises a layer of a BGaN material under the channel, with an average boron concentration of at least 0.1%, improving the electrical performance of the transistor. Application to microwave power components.

Abstract: A bipolar transistor in which the emitter possesses a double "mesa" structure so as to achieve the maximum avoidance of the phenomena of electron/hole recombinations that have a deleterious effect on the current gain. The double mesa emitter can be made out of an alternation of materials M.sub.I /M.sub.II having different types of behavior with respect to a pair of etching methods. These materials may be GaInP and GaAs.

Abstract: The aim of the method is to prevent parasitic metallizations on the lateral walls of a raised pattern, which is used to self-align the electrode metallizations in a transistor. To this effect, a pair of semiconductor materials is introduced into the vertical pattern. These semiconductor materials react differently with respect to a pair of etching methods, so that a layer of one semiconductor material is etched to a greater extent than the other layer. The overhanging feature thus created interrupts the parasitic metallizations, if any, between the electrodes. The disclosed method can be applied to vertical structures.