Thomson-csf

Thomson Hybrides Et Microondes

Thomson-csf Semiconducteurs Specifiques

Daniel Delagebeaudeuf

Henri Derewonko

Patrick Resneau

Pierre Gibeau

Thomas P Pearsall

Ernesto Perea

Trong L Nuyen

Jean J Godart

Didier Meignant

Tranc L Nuyen

Francoise Rambier

Didier Adam

Jean J Godard

Disclosed is a system with at least two complementary transistors, having n and p channels but comprising a heterostructure of junctions between III-V group materials. In order to balance the threshold voltages in the two channels, namely the n (2DEG) and p (2DHG) channels, at least two p and n delta doped layers are included in two layers of the heterostructure, at levels included between the channels (2DEG, 2DHG) and the gate electrodes. The n delta doped layer is then removed by localized etching right above the p channel transistor. Application to fast logic circuits.

Semiconductor device with complementary transistors

A field-effect transistor comprises an ancillary electrode in addition to the source, gate and drain electrodes. In this device, a semiconducting body bears source, gate and drain metallizations which define a main transistor. The metallization of the drain is separated into two parts which are separated by a channel on which is placed a second gate metallization defining a secondary transistor. The two parts of the drain are coupled by this secondary transistor, the channel of which is separated from the main channel. The secondary transistor can be used to control the gain of the main transistor or to modulate its amplitude signal or to mix two frequencies addressed on the two gates.

Field-effect semiconductor device comprising an ancillary electrode

A microwave transistor made with group III-V materials, such as GaAs and AlGaAs, is disclosed. This transistor essentially comprises a double heterojunction formed by a first layer of material with a big forbidden gap, n doped for example, a second non-doped layer with a narrow forbidden gap and a third p doped layer with a wide forbidden gap. Under the effect of the electrical field, there may be formed, simultaneously or not simultaneously, in the second layer, a two-dimensional electron gas at the interface with the first layer and a two-dimensional hole gas at the interface with the third layer. By bringing the thickness of the layers into play, the characteristics of the n and p channels can be made symmetrical.

Microwave transistor with double heterojunction

An ultra-high frequency transistor is mounted in a hermetically sealed package in order to be made usable and in order to improve its performance characteristics to the optimum level. To diminish the noise factor of an ultra-high frequency transistor, the geometrical dimensions of the gate must be reduced. But the transistor changes its impedance and maximum frequency and can no longer be used in a package or at the external impedance of the circuit. It has to be pre-matched by having a choke mounted between its gate, its drain and the corresponding external connections. Each choke consists of a long metallic wire, forming a hairpin, soldered inside the package between the gate metallization and the internal end of its external connection or between the drain metallization and the internal end of its external connection. The invention can be applied to low-noise ultra-high frequency amplifiers.

Encapsulated low-noise ultra-high frequency semiconductor device

There is disclosed a heterojunction field effect transistor with an accumulation of majority carriers functioning as a high cut-off frequency device in which the transistor uses the properties of the same type GaAs/Al.sub.x Ga.sub.1-x As N-doped junctions with the GaAs being weakly doped. This is used to produce a high mobility of charges in the accumulation layer and is effected by a structure in which the source and drain regions are partially covered by the gate region which is in turn covered by an insulation layer and thereby reduces the access resistances and increases the transition frequencies.

Field effect transistor with high cut-off frequency and process for

The invention relates to semiconductor devices of the transistor type operating at high frequencies. In order to make the drain/source current characteristic linear with the voltage applied to the grid and in order to retain a construction technology which is compatible with existing technologies the invention provides an Al.sub.x Ga.sub.1-x As layer between the substrate and the active GaAs layer. A supplementary, highly doped, GaAs layer and a supplementary semi-insulating Al.sub.x Ga.sub.1-x As layer modify the source and drain access resistances and the output resistance. Application to devices operating at ultra-high frequencies.

Field effect transistor with a high cut-off frequency

An avalanche diode comprising a semiconducting heterojunction (Ga.sub.x In.sub.1-x As/InP) intended to oscillate as an 'IMPATT' diode. It comprises a substrate of n.sup.+ doped monocrystalline InP supporting a series of three layers which are formed by epitaxy and of which the monocrystalline latices match one another namely an InP layer with n-type doping and two layers of Ga.sub.x In.sub.1-x As (best mode: Ga.sub.0.47 In.sub.0.53 As) with n-type and p.sup.+ -type doping respectively, these two layers being of minimal thickness. When a backward bias is applied to the p.sup.+ n-junction, the avalanche phenomenon takes place in the thin n-type layer of ternary alloy.

Heterojunction avalanche diode with a ternary alloy of gallium, indium

An avalanche diode of the IMPact Avalanche Transit Time (IMPATT) type with heterojunction structure of two different semiconductor materials, wherein a semiconductor junction P/N or N/P is located at the interface of the two materials. In order to improve the efficiency of the diode functioning as an oscillator, the impurity concentrations of the semiconductors are chosen so that the avalanche zone is located in one and only one of the materials, the thickness of the materials being determined in conjunction with the impurity concentrations to have transit zones of equal length, thus producing a 'double drift' avalanche zone. In the case of Ge/Ga As the condition to be fulfilled by the impurity concentration K.sub.1 of Ge and the impurity concentration K.sub.2 of Ga AS is very simple:

Avalanche transit time diode with heterojunction structure

A thermo-ionic diode with a very noise figure, using a special semiconductor structure, is provided. The structure comprises, upon a P.sup.+ doped silicon substrate, a succession of N-doped layers whose thicknesses and impurity ratios are designed to optimize the noise figure, a final P.sup.+ type layer covering the structure. The injecting junction of the diode is located at the transition between the said P.sup.+ layer and the nearest N type layer having a weak doping.

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Paris, France

Daniel Delagebeaudeuf