DE1063278B - Flat transistor with ring-shaped base electrode - Google Patents

Description

GERMAN

kl. 21g 11/02

INTERNAT. KL. H 01 I.

PATENT OFFICE

111724 VIIIc / 21g

REGISTRATION DATE: MAY 24, 1956

NOTICE
LOGIN
AND ISSUE OF THE
EXPLORATION PAPER: 13. AU GU ST 19 5 9

In a transistor circuit that operates with high-frequency oscillations, it is known that The frequency sensitivity is limited by the storage of the minority charge carriers. To fix it Due to this disadvantage, transistors have been made which are an extremely small semiconductor crystal use, and where the electrode spacing is kept within very narrow limits. A however, such construction has resulted in a decrease in the value of other equally important properties. So high voltage capacitors have made these circuits difficult to manufacture.

In order to counteract the decrease in gain at frequencies above 1 MHz, one has - as has already become known is - proposed as a semiconductor body, a thick disk made of low-resistance germanium with small propagation resistance to use the capacitance by reducing the PN areas reduce and decrease inertia by making a thin, active PNP zone, In this known alloyed high-frequency junction transistor is the base connection with the collector pill on the same surface side of the semiconductor body, but with the proviso that the semiconductor body at the point where the collector pill is located, has a strong constriction.

In contrast, for a planar transistor with a ring-shaped base electrode, there is another electrode on the same surface side of the semiconductor body concentrically encloses the invention therein, that the ring-shaped base electrode attached directly to the semiconductor body is the collector electrode surrounds that. these two electrodes are attached in the same plane on the semiconductor body are, the thickness of which is almost equal to the propagation distance of the minority carriers with average lifetime im Semiconductor body is, and that on the other surface side of the semiconductor body, the emitter electrode on a semiconductor layer of opposite conductivity type, much smaller thickness and is attached with a significantly lower specific resistance than the semiconductor body and thereby an effective and controllable PN junction is formed as an emitter.

In the case of the junction transistor according to the invention, a constriction of the thickness is difficult to produce Semiconductor body under the collector electrode not required. The invention also has over the Known the advantage of the more favorable field line distribution. In the case of acquaintances, the field lines can preferably run from the base connection only to the edge lines of the collector pill, but not into the penetrate narrow semiconductor area between emitter and collector.

Junction transistor
with ring-shaped base electrode

Applicant:

IBM Germany

International office machines

Gesellschaft mbH,
Sindelfingen (Württ), Tübinger Allee 49

Claimed priority:
V. St. v. America May 25, 1955

Richard Frederick Rutz, Fishkill, NY (V. St. A.),
has been named as the inventor

The use of ring base electrodes in transistors is known per se. But they are with the acquaintance not directly on the semiconductor body, but on another, flat base electrode and concentrically surround the emitter electrode.

The invention will now be described in more detail with reference to the drawings for some exemplary embodiments explained.

Fig. 1 shows the electric field created in a structure according to the invention;

Fig. 2 is a circuit for explaining the operation;

Fig. 3 is a circuit with an externally applied power source;

Fig. 4 shows a circuit with an automatic preload adjustment;

Fig. 5 shows the collector and emitter currents as a function of time;

Fig. 6 illustrates a vibrator employing an assembly according to the invention;

Fig. 7 shows the collector current curve of the circuit of Fig. 6;

Fig. 8 shows a transistor with a widened one Junction emitter, a point contact collector according to the invention;

Fig. 9 shows a transistor in which all electrodes are on the same side of the body, which according to the Invention is designed, are attached;

Fig. 10 illustrates a transistor with an emitter located around and opposite the collector Base is arranged according to the invention;

909 607/300

11 shows a widened layer emitter and a collector with a PN hook of a transistor according to FIG the invention;

12 shows a ring-shaped layer emitter and a PN collector with PN hook of a transistor according to the invention.

In Fig. 1, a transistor is shown in which a structure according to the invention is used and on the basis of which the mode of operation is explained. The transistor of FIG. 1 contains a semiconductor crystal with a zone 1 of one conductivity type and a zone 2 of the opposite conductivity type, which are separated by a boundary layer 3. The thickness of zone 1 is selected such that it is almost the same, but preferably less than the distance of propagation of the minority charge carriers with an average service life in the semiconductor material. The thickness of zone 2 is sufficiently thin that it has essentially the same potential in the case of an ohmic contact 4 which extends over almost the entire surface of zone 2. Furthermore, the specific resistance of zone 2 should preferably be much lower than that of zone 1 in order to achieve good emission performance and control of the charge carriers. An electrical point contact electrode 5 makes contact with the zone 1 on the side opposite the ohmic connection 4; a circular electrode 6 makes ohmic contact with the zone 1 on the same side in the vicinity of the point contact 5. In the above-described transistor structure it is assumed to explain the structure according to the invention that the layer 3 serves as an emitter layer and the point contact 5 as a collector with an amplification factor which is greater than i + b , where b denotes the ratio of the mobilities of the majority and minority charge carriers in the N-zone 1, and that furthermore the ohmic electrode 6 is the base electrode.

The operation is as follows: It is assumed that zone 1 is of the N conductivity type and zone 2 is of the P conductivity type. The collector 5 is such a point contact that it has a gain factor greater than 1 + &, on the basis of which more than b additional electrons are released which fly to the base 6 for each defect electron that reaches the collector 5 from the separating layer 3. In this exemplary embodiment, the base 6 is a circular electrode which is mounted concentrically to the collector 5. With this construction, electrons get from the collector 5 to the base 6 when a hole current is emitted at the emitter separating layer 3, as a result of which the axially symmetrical electric field in the crystal 1 around the collector 5 is increased. A gain factor greater than 1 + b is required to ensure that the electric field is strengthened when the hole current increases, since a change in conductivity alone suppresses the electron current at a factor of b. This electric field has an inwardly directed horizontal component which tries to direct the hole current from the emitter separating layer 3 to the collector 5 and to accelerate it. As a result of the electric field, the emitter separating layer 3 is biased more in the direction of the unbound current immediately below the collector point than at the more distant points; therefore seeks to restrict the emission of the holes to areas under the collector and to limit. In FIG. 1, the electron current flow is indicated symbolically by arrows 7 in the crystal from the base 6 to the collector 5. The horizontal components of the electric field, which run tangential to the direction and in the same direction as the lines of the electron flow 7 at each point in the crystal 1, are symbolically represented in the same way as arrows 8.

A further explanation of the electric field is to be made in connection with the circuit according to FIG. 2, in which the base electrode 6 of the transistor according to FIG. B. the battery 10 is connected. Positive signs are introduced to the emitter via input terminals 11 and 12. At the terminals 13 and 14 an output signal appears above the load impedance 9. Under these circumstances, when a positive input sign is applied to terminals 11 and 12, P-zone 2 will be positively biased with respect to N-zone 1, and holes will appear on emitter interface 3. This hole current flows to the collector 5, and as a result of the gain factor a of the collector 5, an electron current flows to the base 6 along the lines which are symbolically indicated in FIG. 1 as arrows 7. An electric field or a voltage drop in the crystal is assigned to this electron flow in such a way that the voltage changes from the negative value at the collector 5 to ground potential at the base 6. This electric field has the appropriate direction in order to direct the positively charged holes to the negative collector 5 and to accelerate them. The field vectors, which are symbolically shown in FIG. 1 as arrows 8, run tangentially and in the same direction as the lines of the electron flow and indicate the direction of the forces which are applied to the positively charged holes by the electric field. Since the collector is located in the middle of a hole in the base in the exemplary embodiment, the holes occurring somewhere on the separating layer 3 seek to align themselves through the electric field and are moved by this to the symmetrical center of the transistor, where the collector 5 is located, accelerated. However, at long distances the electric field will be weak, but the vast majority of the holes will be emitted just below the collector point as shown. As has already been stated, the electric field is very intensified below this point, since a larger current of holes reaches the collector 5. This biases a limited area of the large separating layer much further in the direction of the current flow, so that essentially all the holes emitted are emitted from this small area directly below the collector 5. Thus it should now be stated that one of the essential effects achieved by the structure according to the invention is that only a very small part of a physically large interface emitter is effective due to the electric field generated in the crystal by such Arrangement of the electrodes is set so that the electron flow in the crystal builds up an electric field, which in turn limits the area of the emitter of the holes and directs the emitted holes within the crystal on the collector and accelerates them.

In addition, it can be seen from the above that, if only a sufficient one Number of holes emitted is intercepted, the effect of the field and the resultant increased concentration together create an inner positive feedback that grows, until the internal resistance of the transistor is very low. The current in the collector

The circuit reaches a value that is essentially limited by the resistance in the collector circuit. Every time the emitter current supplied from the outside is not sufficient to drive the collector current into the saturation area, a sufficient special current to achieve this for a short time is generally supplied by the emitter internal capacitance, which will be described in detail later. Under these collector current conditions, the voltage level of P-Zone2 reaches a value which is close to the voltage level of collector 5 and is negative with respect to earth. Since all separating layers in semiconductor crystals and all external lines, even if they are short, have a certain intrinsic capacitance, the voltage. of P-zone 2, which becomes negative with respect to earth, charge this capacitance which, at the end of the input character, prevents P-zone 2 from immediately increasing the output character voltage level. Therefore, at the end of the pulse applied to terminals 11 and 12 of FIG. 2, the voltage level of the P-zone is temporarily held to a negative value with respect to earth by charging the punctiformly distributed capacitances of the separating layer 3 and the external lines. This is a considerable advantage because it creates a second collection point, so to speak, for the holes that are necessarily stored in the N-zone 1. In a common design, holes stored in the crystal at the end of the pulse duration continuously reach the collector and prevent the current in the collector circuit from resuming the switch-off level. This continues until the charge carrier lifetime of the material, which when operated at sufficiently high frequencies can constitute a substantial part of the pulse repetition frequency. Under the conditions given above, the hole storage is greatly improved. Since at the end of the pulse duration the collector 5 and also the emitter separating layer 3 are negative with respect to the positively charged holes, these stored holes have two collecting points which are close together. Since the N-zone 1 has a thickness which almost corresponds to the distance of propagation of the charge carriers during the charge carrier lifetime of the material, the provision of two collection points for the stored holes, which are only separated by this distance, would reduce the hole storage time by a considerable fraction, which is about half of the maximum life of the charge carrier.

Other factors that are important to the decay time of fast pulses are as follows: The saved holes are made by the forces. of a distracting field that instantly changes adjusts in the crystal in that both collection points opposite the positively charged Crystal are negative. Despite sudden collapse, the electric field exerts a certain force the holes near the collector. As a result of the close proximity of the electrons that make up the electrical Field, a strong reunification of the holes and electrons takes place. Just that Holes that get to the collector 5 affect the pulse decay time; those arriving at the separating layer 3 Holes only serve to charge the punctiform equalize the distributed capacitance of the separating layer and the external lines. Another one The factor is the close proximity of the ohmic base connection, which also reduces the reunification which affects holes.

It is clear that there is an improvement in the rise time is achieved by eliminating the electric field within the crystal prior to introducing an input mark is constructed. An even greater advantage of this arrangement is that the time which is necessary for the holes emitted in the crystal at the beginning of the entrance sign

* to walk through the N-zone to collector 5 and around to build up the electric field is greatly reduced

ίο will. If the electric field in the N-zone does is built up, all holes sent out as a result of the entry sign are directed immediately and accelerated towards the collector.

In a method of building this electrical A small direct current should be provided through the transistor in the field. However, be on this one Point highlighted what has already been stated that when charge carriers get to the collector, through the internal positive feedback of the through

ao let resistance is reduced by the transistor in such a way that the emitter is actually more negative and the collector potential is reached when the positive current increases. This creates a negative one Resistance at the emitter, so that when the electric field is built up in the crystal, the direct current must be kept by the transistor at such a low value that it is when the field in the crystal is of sufficiently small strength that the inner positive feedback through the inner \ ^ losses in the transistor cannot begin. The point at which the forward current is strong is enough to initiate the inner positive feedback is best construed as the point the emitter begins to become more negative as the increase in positive emitter current occurs. A typical circuit example for supplying this direct current is shown in FIG differs from the circuit of FIG. 2 in that a positive voltage source 15 and a resistor 16 is connected in series between ground and the electrode 4 to provide a constant direct current in To provide forward direction through the transistor. An input impedance 17 is between the electrode 4 and earth; positive input characters are applied to terminals 11 and 12 between this impedance 17 created. In this circuit, the values for voltage source 15 and impedance 16 are selected so that that a constant current is created through the transistor, which is large enough to generate the electric field in of zone 1.

Another method of execution, in which a direct current of sufficient strength to build up an electric field is supplied in the crystal, uses a voltage of its own generating circuit already proposed. This circuit has two current paths from the base to the collector. One runs directly from the base to the collector through the crystal and the one other, which has a lower impedance than the first, from the base to one at a uniform Voltage interlayer emitter and then from this interlayer emitter to the collector, so that as a result of these currents, a voltage drop occurs in the crystal which forms part of the interface emitter biased in the forward direction and a self-adjusting bias on Emitter which is equal to the resistance drop from the base to the emitter. This the bias self-adjusting circuit, which has already been proposed, supplies a direct current (see. Fig. 4),

in which the distance from the base 6 to the collector 5 has been increased so that the self-adjusting bias occurs; an input impedance 17 lies between the P-zone 2 and ground, whereby the P-zone 2 assumes a negative voltage with respect to ground. With such a transistor structure, two current paths are created from the base 6 to the collector 5. The first current path runs directly from the base 6 to the collector 5 via the N-zone 1, so that there is a voltage drop from ground at the base 6 to the negative at the collector 5 builds up. The second path runs from the base 6 through the N-zone 1 and the separating layer 3 to the P-zone 2 and from there back through the separating layer 3 to the collector 5. Since the distance from the base 6 to the collector 5 has increased, while the Strength of the N-zone 1 has remained the same, namely the same or almost the same as the path of propagation of the charge carriers with an average service life of the semiconductor material, this path has a lower impedance than the first, and the P-zone 2 has a potential that is between the the base 6 and that of the collector 5, that is, it is negative with respect to the base 6, but positive with respect to the collector 5. Thus, a circular line of equal potential is set in the crystal in this embodiment, which corresponds to the point in the voltage drop between the Base 6 and the collector 5 corresponds, which is equivalent to the assumed voltage in the P-zone 2. The circular line of equal voltage is indicated symbolically in FIG. 4 at point 18. Along the separating layer 3, since the P zone 2 is at the same voltage, the separating layer 3 is counter-prestressed between the line 18 and the base 6 and is prestressed between the line 18 and the collector 5. Therefore, in the construction of the transistor according to the invention, a direct current in the forward direction through the transistor, which builds up the electric field in the N-zone 1, is provided.

As a point contact collector transistor of the invention is constructed in accordance with, operates on an output character at the separation layer emitter is known from Fig. Refer 5, in which the curve A, the emitter input character, the curve B the collector current of the transistor in a structure according to the invention, and Curve C represents a collector current of a transistor having a structure according to the invention with a direct current in the forward direction to build up the electric field in the crystal. In FIG. 5, curve A shows an emitter current pulse with a duration of half a microsecond. .

From curve B in the embodiment of the transistor according to the invention, an initial delay can be seen during which the charge carriers only propagate over the base. But as soon as the first charge carriers reach the collector, the internal positive feedback quickly builds up the electric field, which drives the spreading charge carriers to the collector and allows the current to rise in a much shorter time than would otherwise be the case with normal spreading. This time is denoted by Tr. In addition, a current surge occurs up to point X before the current assumes a direct current state Y. This current surge occurs partly as a result of the capacitances mentioned above, which the separating layer and the external lines have, and partly as a result of the effect of the electric field, which is suddenly created by the internal positive feedback when many charge carriers occur and are directed, which propagate through the crystal to the collector , is being built. The usefulness of this rush current will be described in detail later. At the end of the pulse, the current drops due to the two collection points and a third point, the recombining point for the holes, which is close to the base, resulting in a very short fall time Tf . This fall time does not last; longer than the carrier life of the material.

According to curve C , the electric field is already built up in the crystal due to the direct current flowing in the forward direction. As a result, the very first charge carriers emitted are directed and accelerated by the electric field, so that the rise time Tr is reduced even more, since even less time is required for the charge carriers to travel the distance from the emitter to the collector and for the internal positive feedback to set in. Therefore, the current rises in a considerably shorter time Tr to point X and then falls to point Y and then at the end of the pulse during time Tf to the DC value.

From a comparison of curves B and C it can be seen that a transistor with the structure according to the invention responds more quickly to input pulses during the rise and fall. In addition, a rush current is obtained with the rise of the collector rush current, which can be used for a high frequency vibrator as will be described later.

Since the rise time Tr depends above all on the propagation of the charge carriers through the crystal from the emitter to the collector, it should be noted that by changing the base strength and by suddenly changing the collector potential, a transistor circuit according to the invention can easily be manufactured in a short Emitter input pulse of less duration than Tr responds, thereby providing a sharp output pulse with considerable gain.

The current surge at point X of curves B and C can be used very advantageously to provide the time base for a very reliable high-frequency oscillator. This oscillator can be more easily explained with reference to FIG. 6 which shows the transistor which has been described as far as is necessary for an understanding of the invention and which is connected so that it operates as a high frequency oscillator. According to Fig. 6, a direct current is supplied in the forward direction through the transistor by the connection of the voltage source 19 and the resistor 20, which are between the emitter terminal 4 and ground. The capacitances of the separating layer 3 and the outer lines are shown combined as a single capacitor 21, which is shown as a switching element 21 by dashed lines. In operation, the forward current through the transistor has a value large enough to initiate the internal positive feedback but which is less than the saturation current value. The forward current increases sharply when the internal positive feedback increases the electric field and the discharge of the capacitor 21. The holes that emerge from the crystal due to the suddenly intensified field provide a surge of electricity. At the peak of this current surge, at point X in curves B and C of FIG. 5, the P-emitter zone 2 becomes more negative than the N-zone 1, so that after the charge on the capacitor 21 has been consumed by this capacitor P-Zone 2 is held at this negative value until the current

in the forward direction from the voltage source 19, the capacitor 21 via the resistor 20 again can charge. After the charge on the capacitor at the top of the surge current is depleted, it turns on of the N-Zone 1 the DC potential is restored. When the capacitor 21 has the P-zone negative keeps biased, the separating layer 3 is counter-biased, and the collector current falls. The collector current remains low until the voltage source 19 recharges the capacitor 21 via the resistor 20 can. It should be noted at this point that the time constant of the i? C network from the Resistor 20 and capacitor 21 regulates the oscillation frequency. With a suitable choice of value a certain value of the oscillation frequency will result for the resistor 20. Another frequency control range can be achieved by the construction of the transistor and the lines by the Resistor 20 and capacitor 21 can be regulated.

In Fig. 7 is a graph of the current flowing through the resistor 9 collector current of Schwingungserzeug'ers of Fig. 6 is shown in which for the initial direct current through the transistor, an arbitrary value is selected which is registered as the value / c at time 0. According to both FIGS. 6 and 7, the current increases when the capacitor 21 of FIG. 6 discharges until the amplitude has reached point A. At this time, the capacitor 21 is discharged and cannot maintain the strong current. Furthermore, as a result of the internal positive feedback when reducing the resistance in the forward direction through the crystal, the capacitor 21 now has a charge which keeps the P-zone 2 at a negative potential value, which is assumed in the case of the strong current. If P-zone 2 has this negative value and cannot maintain the high current value at point A in FIG. 7, the current through the transistor will be blocked. Since P-Zone 2 is negative compared to N-Zone 1, the separating layer is counter-biased. After blocking the current, the collector current drops sharply if there are no charge carriers; meanwhile, the voltage source 19 charges the capacitor 21 via the resistor 20. When the capacitor is charged so that it no longer holds the P-zone 2 negative, a current is again supplied through the transistor from the voltage source 19. The collector current stops falling at the same time (see. Fig. 7, point B). The forward current through the transistor initiates a new oscillation period of the current, which is shown by the following points and B.

The vibration generator described uses a combination of point-like distributed capacities and from an internal electric field in an interface emitter transistor, so that a Vibration generator with very few switching elements with a very high vibration frequency and good Output power arises. This vibrator is because a time base is directly related to the quantities depends on the semiconductor arrangement used, very reliable.

In the structure according to the invention, the electrodes are applied to the crystal of a transistor are designed such that they are advantageously exposed to the changing fields for the base region will. This is achieved in that such contact arrangements are provided that the The flow of the majority charge carriers from the collector to the base creates an electric field in the crystal, which is brought close enough to the emitter by the geometry of the transistor to to accelerate the minority charge carriers and direct them to the collector. At the same time be through this electric field achieves further advantages, which consist in the minority charge carrier storage time to reduce, and a negative resistance range in the emitter characteristic arises, so that

ίο the emitter potential becomes negative at high currents and remains negative after the applied exit impulse has subsided and thus acts as an additional collection point for the minority carriers. It has therefore been established that there is a certain Distance between emitter and base; and collector electrodes in the transistors according to of the invention can be constructed. This range of distances is determined by the carrier lifetime of the semiconductor material, by the specific resistance of the semiconductor material and by affects the collector voltage applied to the transistor. The minimum range of distances is determined by the requirement that the emitter and collector on the semiconductor crystal by a sufficient Distance are separated from each other, thus a rollover as a result of the applied to the collector Voltage does not affect the transistor properties. The rollover is due to the expansion of the to an area with an exhausted supply belonging to a counter-tensioned separating layer, the under an electrical point contact collector or a collector with NP protrusions of the crystal is located until it influences the emission of the charge carriers through the emitter. An upper limit of the Electrode spacing between emitter and collector, so that the internal positive feedback exist can, in the vicinity of the path of propagation of the average excess charge carrier during the charge carrier lifetime. The excess charge carriers are defined as those charge carriers which are in equilibrium the majority and minority carriers exceed. Otherwise the internal losses like the reunion in the crystal; be so great that by concentrating too much of the Minority charge carriers this feedback state could not arise. Hence a certain field strength required so that an internal positive feedback in the electrode arrangement according to FIG. 1 occurs.

In order to achieve positive feedback in a semiconductor with an electrode arrangement according to FIG. 1, the electric field must be well bundled, ie an electric field must be generated, the effect of which is limited to a small area of a broad emitter. For each point in the N-zone which is close to the emitting region in the semiconductor crystal and which has a distance d from the collector which is equal to the distance from the collector to the base or equal to the distance from the emitter to the base, as the case may be whichever is lower, it is sufficient that the electric field at this point is 0.1 volts for the distance d from the collector in order to achieve sufficient bundling for the internal feedback:

Several arrangements according to the invention have worked well when reducing the spacing between emitters and collector is within the propagation distance of the average excess charge carriers at their average Life of the semiconductor material is located and if the point contact collector with the N-zone

909 607/300

11 12

makes contact in an opening in the base, the lines of force of the majority charge carriers are through

has a diameter which is indicated within the five arrows 7.

As can be seen from the exemplary embodiments of the transistor shot charge carrier in the charge carrier duration according to the invention, the semiconductor material can be located. In order to ensure the inner positive 5, the dimensions of the transistor within a wide range of feedback, without any undue changes. However, all structures have a comfortable high gain from the collector required - a PN separating layer with a wide area, which is called Hch - if the output power of the emitter is to serve the emitter, a collector with a high intrinsic value must be adapted to the separating layer gain factor a that is greater than 1 + b , and emitter can be achieved. io an ohmic base connection that is spatially so. After explaining the operation of the structure it is arranged that the majority charge carrier ^{current according to the invention should be mentioned that this electrical field can be changed from} the base to the collector in the structure of the transistors. The crystal that is used to accelerate and direct the minority charge carriers according to some embodiments of transistors, which are of the invention are shown in FIGS. 8 to 12. 15 are sent out from the emitter to the collector. . : According to Fig. 8, the transistor of Fig. 1 has the effect of this field, these charge carriers are concentrated in the N-zone 1 between the base 6 and the collector 5 crystal in such a way that the forward resistance, which is partially eliminated in the region 22, is In order to stand the transistor in this area, the electron flow from the base 6 to the collector 5 is reduced and the emission of the minority charge is directed closer to the emitter separating layer 3. The 20 carrier from the wide-area separating layer thereby P-Zone 2 A is designed in such a way that in the N-Zone 1 is electrically restricted to a small area,
a suitably contaminated material 23 is admitted, while this structure corresponds to the state at which an ohmic contact 4 A is attached. The construction of FIG B, the ^Fi S · "1 i" combined with the circuit of FIG. 3 5 surrounds the collector, and was added with an ohmic ⁱⁿ the following table. the contact 45 is provided. a ring-shaped ohmic I "values in this table are given for only as a base contact 6 A is concentric to the emitter and example, and the invention is not intended to relate to the collector. Since all electrodes are restricted to the same side 30.

the N-Zone 1 are applied, the field for the thickness of the N-Zone is 0.025 mm

Majority carrier sending out the minor strength of the P-Zone 0.0025 mm

to prevent charge carriers and this to the part crystal length 0 5 mm

of the crystal in the immediate vicinity of the collector to ^c . '_

to steer. In this version of the crystal, the in-35 - ^ "stable width is 0.5mm

whose the distance from the emitter to the collector un- collector phosphor bronze wire 0.125 mm

important; it should preferably be smaller than the expansion diameter

length of the charge carrier life. Gain factor α of the collective

In Fig. 10, an emitter 2 B and the collector 5 are tor 5

as in Fig. 9 concentrically on the same side of the 40 holes in the base connection 0.075 mm

N-Zone 1 arranged; the ohmic base 6 B is located in diameter

on the opposite side. Here will be in contact with collector point

through the majority carrier lines of force 7 from the N-zone 0.006 mm

from the base 65 to the collector 5 the emission area and diameter

the minority charge carrier flow to the area of the 45] S [-2one 15 Ohm / cm

Crystal directly at the emitter and the '"(more specific
Collector limited. In this design the resistance of the strength of the N-Zone 1 is not critical, but the Förde- ^ ■,
tion regarding the distance between the emitter and the collector should be maintained. 50 ^X - ^Zone · · · °> / ohm / cm

Fig. 11 shows a transistor having a Pezih construction

according to the invention, which has a collector 5 with resistance of the

Has PN hook, which by grinding off un- germanium)

wanted parts of an NPN transistor made battery 10 45 volts

is, and in which an interface emitter zone 2 with 55 battery 15 20 volts

a suitable impurity 21 and resistor 9 500 volts

an ohmic base connection 6 C to the N-Zone 1 in front, ". ,,,., _ ir \ nnnr \ u

. . , _T j. ".." j A-UiJJ resistor 17 10, UUU Ohm

is seen. In this case, the distance of the

N-Zbne between emitter and collector to the resistance 16 20,000 ohms

the value given above can be adjusted. 60 input character pulse 5 milliamps

The lines of force of the majority carrier current at a duration

are shown as arrows 7. from 50 milli-

In Fig. 12, a transistor electrode arrangement is seconds

illustrated; which is similar to that of Fig. 10 and thereby output character pulse 50 milliamperes

can be made that a standard NPN Tran- 65 at a duration

■ sistor is cut so that a collector 5 with from almost

PN hook arises, and that an emitter zone 2 C at 60 milli-

this. is available. The slots 24 are said to be seconds

• Be tight that the required distance between direct current in the forward direction

Emitter and collector is maintained. The 70 through the transistor 1 milliamp

Under the specified conditions, the strength of the electric field in the crystal can be almost can be calculated exactly from the following equation:

^E (a) = -

2 π α ²

1 -

where α * is the amplification factor of the electronic collector equal to 5, b is the mobility ratio of the charge carriers, the value of which for germanium has been chosen to be 2, P ₀ the specific resistance of the N-zone is set equal to 15 Ohm / cm, Ic the collector current during the rise time is arbitrarily set to 20 milliamperes, α is the radius of the collector point contact at which the field strength has been calculated and is equal to 0.01 mm, and E is the field strength in volts / cm.

At a distance of the base electrode of 0.01 mm from the collector, E is approximately equal to 19.4 volts / cm.

The formula given above is imprecise in that it neglects the propagation currents in the crystal and the shapes of the electronic area under the collector and emitter area are assumed to be hemispherical.

Various switching elements can be omitted or replaced by others. So z. B. the N and P zones are interchanged. Gold-plated electrical point contacts can also be used can be used with collectors with PN hook.

Claims (11)

Claims 1. Flat transistor with ring-shaped base electrode, the other electrode concentrically on the same surface side of the semiconductor body encloses, characterized in that the ring-shaped and directly on the semiconductor body attached base electrode (6) surrounds the collector electrode (5) that these two Electrodes (5, 6) are attached in the same plane on the semiconductor body (1), the thickness of which is almost equal to the propagation distance of the minority carriers with an average lifetime in the semiconductor body is, and that on the other surface side of the semiconductor body is the emitter electrode (4) on a semiconductor layer (2) of the opposite conductivity type, much less Thickness and attached with a significantly lower specific resistance than the semiconductor body and thereby a controllable PN junction (3) which is effective as an emitter is formed. 2. junction transistor according to claim 1, characterized in that the mutual distance is chosen between the emitter, the base and the collector electrode such that the in the Semiconductor body generated the emission of minority carriers to only as small a field as possible Part of the PN junction that acts as an emitter is limited. 3. Surface transistor according to claim 1, characterized in that the ohmic base electrode is removed from the emitter electrode and the collector electrode in such a way that in the semiconductor body an electric field is created through which the minority carriers emit from the emitter electrode flow to the collector electrode, are bundled. 4. Surface transistor according to one of the preceding claims, characterized in that An opening, in particular a circular opening, is present in the base electrode, the Diameter at most five times as large as the mean distance of propagation of the excess charge carriers is during the charge carrier life in the semiconductor, and that an electrical Point contact collector is in contact with the semiconductor body in the opening. 5. junction transistor according to claim 1, characterized in that part of the semiconductor body (22) between the base and collector electrodes is removed (Fig. 8). 6. junction transistor according to claim 1, characterized in that all electrodes are on the same Surface side of the semiconductor body are attached and that the base and emitter electrodes surround the collector electrode concentrically (Fig. 9). 7. junction transistor according to claim 1, characterized in that the collector electrode is a P- and an N-layer is upstream. 8. Circuit using a junction transistor according to claims 1 to 7, characterized characterized in that at a reference potential point, in particular earth, the negative pole of a DC voltage source (15), the positive pole of which is connected to the emitter electrode via a resistor (16) (4) is connected, that a further voltage source (10) is also connected its positive pole is connected to the reference potential point, while its negative pole is connected to the collector electrode via a further resistor (9), and that the base electrode is connected to the reference potential point (Fig. 3). 9. A circuit according to claim 8, characterized in that in parallel with the series connection from the first voltage source (15) and the one resistor (16) another resistor (17), the ends of which are connected to the input terminals (11, 12), to which input pulses are applied, and that of the further Resistance at the collector electrode (9) to the output voltage is removed via the terminals (13, 14) (Fig. 3). 10. A circuit according to claim 9, characterized in that on the other parallel Resistor (17) in the emitter circuit automatically adjusts the bias (Fig. 4). 11. Circuit according to claims 1 to 10, characterized in that it is used as a high-frequency oscillation generator works and that the punctiform distributed capacitances of the emitter electrode and the lines serve as capacitance. Considered publications:
German patent application ρ 49066 VIIIc / 21g (announced on March 1, 1951);
The Bell System Techn. Journ., Vol. 33, 1954, No. 3, Pp. 517 to 533; Journal of Electrochemistry, Vol. 58, 1954, No. 5, Pp. 283 to 321 (314). 1 sheet of drawings © 909 607/300 8.