Abstract: A method of preparing faces of a laser based on III-IV compounds, the method comprising the following operations:1) the faces of the laser are opened;2) said faces of the laser are placed in an enclosure in which there obtains a pressure of about 10.sup.-7 mbar to about 10.sup.-8 mbar, and they are subjected to a step of cleaning by irradiation with a pulsed laser; and3) the same pulsed laser is used to ablate a target so as to subject said faces to a passivation operation whereby silicon Si or gallium nitride GaN is deposited thereon by the pulsed laser deposition method until a thickness is obtained lying in the range 2 .ANG. to 20 .ANG..

Abstract: A field effect transistor for high-frequency applications includes, on a monocrystalline semi-insulating substrate, a thin active n-doped layer of a material having a high electron mobility, on whose surface are deposited two ohmic contacts forming the source and drawing contact regions of the transistor, between which a metallic contact constitutes a gate electrode of the Schottky type. According to the invention, the transistor is characterized in that a dielectric layer is deposited on the active layer between the source and gate electrodes on the one hand and between the gate and drain electrodes on the other hand, and in that the metallic layer constituting the ohmic contacts is continuously prolonged on this dielectric layer without causing a short-circuit with the gate.