DE2028657A1 - Semiconductor device - Google Patents

Description

Patent attorneys Dlpl.-lng. R. DSETZ sen. Dlpl.-lng. K. LAMPRECHT

Dr.-Ing. R. BEE TZ Jr.
8 Munich 22, Steinsdorfstr. 10 293-15.780P. June 10, 1970

Minister of Technology in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland, LONDON, S.W.I. (Great Britain)

Semiconductor device

The invention is concerned with semiconductor devices that the Show effect of electron transfer.

The well-known effect of electron transfer is a process in which electrons in a semiconductor body with suitable doping such as cadmium telluride, gallium arsenide or indium phosphide from a conductivity band with high electron mobility due to the application of an electric field of sufficient strength in a conductivity band be transferred from higher energy and lower electron mobility. Semiconductor arrangements that are taking advantage of working with this effect are generally referred to as electron transfer semiconductor devices.

Another well-known consequence of the sheet metal transfer effect is the Gunn effect. This consists of

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the formation of areas of high electric field strength, which are characteristic of the length of the selected sample Frequency migrate through the semiconductor body.

Semiconductor arrangements with electron transfer can be known to use for the generation of microwaves. Unfortunately, however, semiconductor devices are now involved smaller dimensions are severely limited in their output power. Hence it proves to be useful in creating a high frequency arrangement with sufficient output power as necessary to find a way to get high frequency with an arrangement of to produce larger physical dimensions than the conventional arrangements.

The invention therefore provides a semiconductor arrangement with a body made of a body which exhibits the electron transfer effect Semiconductor material of a cathode and an anode created, which is characterized in that the cathode a metal area with good ohmic contact to the semiconductor material and the anode made of a material other than such a metal is a good one Shows charge carrier extraction.

The anode can contain a diode with a Schottky barrier layer or a heavily doped semiconductor material.

In addition to the metal with good ohmic contact with the semiconductor material, the cathode can contain a region made of a heavily doped semiconductor material.

To further explain the invention, preferred embodiments of the invention will now be described in more detail are »illustrated in the drawing. Do it yourself

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in the drawing:

Fig. 1 and 'Fig. 2 cross sections through known semiconductor arrangements with electron transfer;

Fig. 3 shows a corresponding cross section through a

Embodiment of a semiconductor arrangement according to the invention

FIGS. 4, 5, 6 and 7 are plan views of semiconductor arrangements according to the invention and

FIGS. B, 9 and 10 show cross sections through alternative designs for semiconductor arrangements according to the invention.

The half-bender arrangements with electron transfer that have been customary up to now are of two types. The first type uses a high purity epitaxial layer of gallium arsenide, referred to as the η layer, typically having a resistivity of about 1 ohm cm and deposited on a substrate of highly conductive gallium arsenide, the resistivity of which is about 0.01 Ohm cm or less. Such a structure is called a longitudinal structure. One contact point is on the underside of the substrate and the other on the top of the epitaxial layer. This second contact point can be made of metal or it can also be produced in the form of a second epitaxial layer deposited on top of the first epitaxial layer, this second epitaxial ^{layer (the n +} layer) being highly contaminated with a donor impurity is doped and therefore has a low specific resistance, that is to say is highly conductive.

The second so far for semiconductor arrangements «it electron-

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transfer proposed design is illustrated in Figs. In this type of electron transfer semiconductor device, an epitaxial layer 1 becomes high in purity on a substrate 3 made of gallium arsenide of particular and deposited under the name semi-insulating gallium arsenide form. The substrate j5 therefore behaves electrically inert and acts only as a mechanical carrier and as a nucleus during the deposition process. In the drawing an example of a structure known as a transversal structure is shown, in which two contact points on the epitaxial layer 1 are to be attached. In other words, So there are two contacts in a transversal structure to be placed on the same surface. '

In all previously proposed semiconductor arrangements with electron transfer and transversal structure, these are both Making contacts from one and the same material. For example, both contacts can be made of a metal, such as for example a silver-tin alloy, a silver-indium-germanium alloy or a gold-Niekel-germanium alloy, or made of a highly doped epitaxially deposited gallium arsenide deposited on the surface or in prepared recesses is deposited in this surface. All of these working techniques can be used without further ado perform with the usual methods of photo printing, such as them in integrated circuit technology im Use are. Such contacts are shown in FIG. 1, two contacts 5 and 7 being deposited on the epitaxial layer 1 are.

In a second type of contact establishment, doping with an impurity acting as a donor such as Sulfur made during the deposition of the contact

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can be done. According to the theory, the contact areas could be caused by local diffusion of the impurity acting as a donor be generated. In practice, however, you mostly go not so before, as it is very difficult to determine the properties of the treated part of the layers during diffusion maintain. Contacts of this type are illustrated in Fig. £, with two contacts 9 and 11 during the Deposition of the epitaxial layer 1 are produced.

The invention, on the other hand, is used to achieve its goals a semiconductor oscillator with electron transfer effect, the electrodes of which are made of different materials.

Such a structure has not yet been considered because it requires the use of two different technologies for contacting.

Now, however, electron transfer semiconductor devices, both of which electrodes are made of an n ⁺ -doped gallium arsenide, have not been made to work effectively, and electron transfer semiconductor devices, both of which electrodes are made of metals that make a good ohmic contact, do not work either Satisfactory, since metals with good ohmic contact to semiconductor materials with electron transfer such as gallium arsenide, i.e. metals such as tin, indium or alloys of these metals have a low melting point and tend to breakdown under the conditions prevailing at the anode with high field strength and high current density. On the other hand, a good ohmic contact is only required at the cathode, and this type of breakthrough cannot occur at this electrode. The anode, on the other hand, requires an electrode that extracts charge carriers with high efficiency. One

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Electron transfer semiconductor device showing a good Fig. 3 shows ohmic contact at the cathode and effective carrier extraction at the anode.

In FIG. 3, the epitaxial layer 1 made of n-conductive gallium arsenide is grown on the substrate 3 made of semi-insulating gallium arsenide as has been customary up to now. An anode 13 is made from n ⁺ -doped gallium arsenide, which is deposited in a prepared recess in the surface of the axial layer 1. Such an electrode represents an effective extractor for charge carriers. The cathode consists of a region 15 of n ⁺ -doped gallium arsenide, which is deposited in a similar manner to the gallium arsenide of the anode 13, but with a layer 17 of metal partially on region 15 and is partially deposited on the epitaxial layer 1 between the region 15 and the anode. The metal for layer 17 must be chosen so that it makes good ohmic contact with the gallium arsenide; for example, tin, indium or alloys containing tin or indium or both metals are suitable for this purpose. A voltage source V is connected between the area 15 and the anode 13.

The anode 13 and the area 15 can be produced by local epitaxial growth in recesses that pass through Etching of the surface of the epitaxial layer 1 can be generated. Such recesses can have a depth that is less than is just as large or even greater than the thickness of the epitaxial layer 1. Alternatively, the anode 13 and produce the area 15 by local diffusion of an impurity acting as a donor.

There are many for the shape and size of layer 17

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Alternative designs, and accordingly the Invention in semiconductor arrangements with ring-shaped electrodes as is the case with semiconductor arrangements with additional electrodes realize between anode and cathode.

Figures 4, 5, 6 and 7 are plan views of such alternative designs for semiconductor oscillators with electron transfer, the layers 17 of a different shape and size demonstrate.

In Fig. 4 there is a region 15 in Fig.> corresponding area 15a of rectangular shape and to the anode 13 parallel position. Next is one of layer 17 in Fig. 3 corresponding layer 17a is present, which also is of rectangular shape and the area 15a and the area between this region 15a and the anode 13 overlaps.

In FIG. 5, a layer 17b corresponding to layer 17 in FIG. 3 has the shape of a triangle, one of which Tip the area between the area 15a and the anode 13 overlaps.

In FIG. 6, a region 15 in FIG. 3 has a corresponding one Area 15b has the shape of a parallelogram which runs at an angle to the anode 13. One of the layers 17 in FIG. 3 The corresponding layer 17c is also designed in the form of a parallelogram which is parallel to the area 15b Has sides. The layer 17c overlaps the area 15b and the trapezoidal area between the region 15b and the anode 13.

In Fig. 7, which is similar to Fig. 6, the area has 15b

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the shape of a parallelogram running at an angle to the anode 13. One of the layer 17 in FIG. 3 corresponding Layer 17b is triangular in shape, with one corner of the triangle being the area between region 15b and the anode overlaps at their next point.

Fig. 8 is a cross section of part of an electron transfer semiconductor oscillator. The epitaxial layer 1 made of η-conductive gallium arsenide grown on a substrate 3 made of semi-insulating gallium arsenide has several recesses on its surface. In one of them, which is at one end of the semiconductor ^{oscillator, an anode 13 made of n +} -doped gallium arsenide is deposited, and the other recesses contain further electrodes 15j, 15 ₂ "15 *" ... made of n ⁺ -doped gallium arsenide. In addition, several layers IJ ₁ , 17p are deposited on the surface of the epitaxial layer 1, which consist of a metal which gives a good ohmic contact to the gallium arsenide, the layer 17, the electrode 15j and the area between the electrode 15. and the Electrode 15 _g overlaps and the main. cathode area, the layer 17 ₂ the electrode 15 _g "and the area between the electrode 15p and the electrode 15- * overlaps, etc. In this way, each of the layers like 17 ₂ together with an electrode like 15-j forms a semiconductor oscillator Electron transfer, where the electrode 15 acts as an anode and is connected to the next cathode such as the layer 17 ^, and the entire semiconductor arrangement represents a chain of semiconductor oscillators connected in series with electron transfer, which can be fed by a single voltage source V, which is connected between the electrode 15j and the anode 13.

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The voltage source V can equally well be connected between the layer IT ₁ acting as a cathode and the anode 15. In this case, the electrode 15 * can be omitted, as is illustrated in FIG. 9.

Fig. 10 is a cross section through an alternative embodiment for a semiconductor oscillator with electron transfer. The epitaxial layer 1 made of η-conductive gallium arsenide is on grown on a substrate of semi-insulating gallium arsenide, and on the epitaxial layer 1 is again as above Cathode 17 deposited, which consists of a ^ s a metal that results in a good ohmic contact with gallium arsenide. In addition, an electrode 19 is provided, which is connected to the epitaxial layer 1 forms a common Schottky barrier diode and represents the anode. The electrode 19 can off Nickel, which is deposited in such a way that it together with the epitaxial layer 1, a diode with a Schottky barrier layer forms.

A Schottky barrier is known to be a very effective extractor for. Charge carrier, and therefore works the semiconductor arrangement illustrated in FIG. 10 when a voltage source V is connected between the cathode 17 and the anode 19 as an electron transfer semiconductor oscillator.

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Claims (1)

Claims 1 / semiconductor device with a body of an electron transfer effect showing semiconductor material, a cathode and an anode, characterized in that, that the cathode contains a region made of a metal with good ohmic contact to the semiconductor material and the anode made of a material other than such a metal exhibits good carrier extraction. 2. Semiconductor arrangement according to claim 1, characterized in that that anode and cathode are arranged transversely on one and the same semiconductor surface » 5. Semiconductor arrangement according to Claim 2, characterized in that that a further electrode is arranged on the semiconductor surface between anode and cathode, which has a further area made of a metal with good natural contact to the semiconductor material and © ia © B adjoining it contains a highly conductive semiconductor material «, P 4. Semiconductor saoretanng smcSs. © inen Aar Jtasprüßfa © 1 to 3s aa your Btetallisehsn Ββί? © 1 ©! ιο © iE @ ni B © i? Qi © | a öme tenden Hallblei terraaterlal eatMlt ₀ 5 «. H & lbleifcefaaörclarasiig aaefe © ianii öqs ³ üsadpz ^ aSiG 1 to through good conductäea Halfeleit @ FEat @ 2 ° isI 6 _O HalfeleifeeraaoMsiiiiBg zm, © k © ia ©
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