Abstract: A ED-HEMT structure includes a buffer layer (4) including a doped layer (18), a channel layer (6), a barrier layer (8), and a second doped layer (20). An enhancement mode HEMT gate (12) is formed in a via extending through the second doped layer (20) and a depletion mode HEMT structure is formed over the second doped layer (20). The layer sequence allows the formation of both enhancement and depletion mode HEMTs in the same structure with good properties.

Abstract: The method for forming a multi-stage recess in a layer structure comprises forming a photo-resist film atop a layer structure; a first step (49, 70) of etching the layer structure through an opening of the photo-resist film used as a mask, for forming a first stage of the recess; a step of widening the opening of the photo-resist film after the first etching step, for producing a widened opening of the photo-resist film, and a second step (58, 72) of etching the layer structure through the widened opening of the photo-resist film for forming a second stage of the multi-stage recess.

Abstract: The invention relates to a transistor structure with both enhancement and depletion mode transistors. In order to allow good control over the manufacture of both transistors, a first Schottky layer (10) and a second Schottky layer (12) are used made of first and second semiconductor materials respectively. The first and second materials having band gaps of at least 0.5V. For an n-type transistor the second Schottky layer has a low conduction band discontinuity with the first Schottky layer. Both the first and the second Schottky layers are used as etch stops in the method for making the transistor. The transistor is preferably a HEMT.

Abstract: A semiconductor device comprising integrated circuit elements realized by means of a stack of layers of semiconductor materials provided on a substrate of semiconductor material and comprising means for preventing the pollution of the circuit elements and of the substrate by hydrogen originating from their environment is characterized in that said means are formed by a layer of a material which absorbs hydrogen (or hydrogen getter) (10), which forms a pattern which is integrated with the circuit elements and whose outer surface (11) is exposed and in contact with the environment. This device, of the MMIC type, forms part of a module of a spatial or terrestrial telecommunication system.

Abstract: A semiconductor device comprising integrated circuit elements realized by means of a stack of layers of semiconductor materials provided on a substrate of semiconductor material and comprising means for preventing the pollution of the circuit elements and of the substrate by hydrogen originating from their environment is characterized in that said means are formed by a layer of a material which absorbs hydrogen (or hydrogen getter) (10), which forms a pattern which is integrated with the circuit elements and whose outer surface (11) is exposed and in contact with the environment.

Abstract: The invention relates to a method of manufacturing an integrated semiconductor device on a substrate (1), comprising steps to manufacture a stack of layers (2, 3, 4, 5) on the substrate, and steps to manufacture circuit elements by means of photolithography including the formation of a centering mask, the formation of a reference pattern through an opening in this mask, and the formation of masks for defining circuit elements centered on the reference pattern.

Abstract: A semiconductor device comprises a chip soldered to a support. The chip comprises a semiconductor substrate, a via a ground plane on a rear surface, and an anti-adhesion layer deposited continuously inside the via. A solder layer which does not wet the anti-adhesion layer but which does wet the ground plane has a globular shape in the via opening and makes no mechanical contact with the walls of the via. The manufacturing process comprises the sandwiching of a soldering preform between the support and the rear surface provided with the ground plane and said anti-adhesion layer, and melting of the preform under pressure so that the solder rises in globular shape inside the via. The anti-adhesion layer is realized without mask.

Abstract: The invention relates to the measurement of the ovalization of a ferromagnetic pipe.An electromagnetic pickup is moved in a circular path around the pipe, the pickup transmitting signals influenced by the radial distance between the pickup and the pipe. These signals are compared with signals from previous measurements made on a similar pipe to obtain indications of the radial distance between the pickup and the pipe so as to be able to deduce the transverse configuration of the pipe. The pickup is supplied with ac at a frequency of about 700 Hz and the signals from the pickup are compared with previously obtained signals both as to amplitude and phase.The pickup is mounted on a circular slide movable along a circular track supported on a U-shaped collar which is fixed to the pipe.

Abstract: Particular Syn (--NHCH.sub.3) geometrical isomers of cyano-guanidines are disclosed as new compounds having activity as histamine antagonists useful in the treatment of gastric and duodenal ulcers.

Abstract: Therapeutically active compounds of the general formula: ##STR1## wherein Ac.sub.1 is a first acyl group, Ac.sub.2 is a second acyl group different from Ac.sub.1, A is a C--C bond or a divalent organic residue; R.sub.1, R.sub.2 are a hydrogen atom or a lower alkyl group, R.sub.1 and R.sub.2 together being able to take part in the formation of a ring having up to 6 atoms, A, R.sub.1 and R.sub.2 may be substituted by -OH groups esterified or not by acyl groups.