JP4925508B2 - Switching element - Google Patents

Description

[0001]
(Technical field of the invention and prior art)
The present invention has two terminals connected to each other by one or more material layers, and when a voltage is applied between the terminals, a conductive state that conducts current between the terminals and a charge carrier between the terminals The present invention relates to an element that switches between a blocking state and a blocking state that prevents the movement of the.
[0002]
Therefore, the present invention relates to a switching element in the broadest sense of this expression, and the conduction state conducted when a voltage is applied between the terminals and the movement of charge carriers between the terminals are the voltages between the terminals. For all types of elements that are adapted to assume a blocking state that is blocked regardless of the application of. This element is in the conductive state and has the opposite voltage direction to the blocking state. The simplest element type is a rectifier diode, but the voltage is applied in exactly the same direction between the terminals. It may be of a type that can assume either a conduction state or a blocking state when done.
[0003]
The definition of “terminals interconnected by one or more material layers” defines a circuit that achieves a switching operation by breaking and establishing physical connections between the terminals of the element, ie connecting or disconnecting them. Used to delimit the invention with respect to breakers or switching elements. In contrast, the physical properties of the material layer related to charge carrier and voltage availability will determine the state of the device.
[0004]
There are many applications for this type of device, but the use of such devices for high power applications will be described in detail below in a non-limiting manner.
This type of device is used in devices that handle high power to switch between high voltage and high current, such as circuit breakers, commutators, current valves, surge diverters, current limiters, and the like. In many of these applications, the breakdown voltage of such devices is significantly lower than the voltage to be held by the location where the device is placed in the device, so that to distribute the total voltage between the devices, It is necessary to connect a relatively large number of such elements in series. The total voltage may exceed 100 kV, but a single element has a breakdown voltage of, for example, 2-5 kV. Controlling such elements requires a large amount of complex and expensive equipment, and the equipment for cooling them, especially in high frequency operation, for example, the elements are pulse widths at the converter station. When used in current valves that are switched according to modulation (PWM), they are relatively complex and expensive. In fact, the majority of the cost of the converter station comes from the control and cooling device, so in such stations and high power applications, the number of such elements is greatly increased to save cost. Reduction is strongly desired.
[0005]
(Summary of Invention)
The object of the present invention is to provide an element of the type defined at the outset in order to reduce the known problems in the element described above.
An object of the present invention is to provide a first layer of intrinsic diamond, a second layer adjacent to the first layer, and a second layer to be moved through the diamond layer by voltage. Means for switching to the blocking state by stopping the supply of the free charge carriers for the movement by supplying free charge carriers, and the diamond layer comprises: This is accomplished by providing a device adapted to block most of the voltage across the terminals in the blocking state.
[0006]
The main advantage of such a device is that diamond has a very high breakdown field strength, which means that the number of elements to be connected in series in order to hold a constant magnitude voltage, Even if the device itself is much more expensive than the prior art device and the others have no obvious facts. , Can greatly reduce the cost. Traditionally, it has been difficult to dope diamonds to date, and intrinsically undoped diamond has not been used in semiconductor devices in the active layer of devices that conduct current, but mainly as a gate insulating layer. It can be considered as a material suitable for use in a simple insulating layer and can benefit from its superior insulating properties.
[0007]
However, the inventors of the present invention have found that the intrinsic diamond layer works very well in this type of device, while the very high breakdown field strength of diamond is used for the blocking state of the device, while the The device is in a conducting state by providing free charge carriers in the second layer to allow conduction of current through diamond having high conductivity due to the relatively high charge carrier mobility in intrinsic diamond. Has been found to be able to conduct current without significant loss. The term “intrinsic diamond” means that the diamond layer is neither doped nor compensated and the dopant is not thermally activated at the desired temperature.
[0008]
In addition, diamond has the highest known thermal conductivity of any solid near room temperature, which is particularly the heat sink in high frequency devices where cooling limits the achievement of higher switching speeds. It is well suited for high power applications such as The high breakdown field strength of diamond means that for the same breakdown voltage, for example, a diamond layer can be made much thinner than a layer made of Si, which creates problems in switching loss and reverse recovery. It can be greatly reduced, thereby improving the switching speed. In addition, the short carrier lifetime allows for higher switching speeds within the diamond element. Another advantage of using diamond is that it is extremely temperature stable, in that sense its thermal expansion is very small, and its large band gap (5.4 eV) insulates to high temperatures Maintaining the material means that it works well even under high temperature conditions of the order of 1000K, so that the device can be used for such applications.
[0009]
According to a preferred aspect of the present invention, the second layer is made of a material having an energy gap substantially smaller than diamond between the valence band and the conduction band, and the means includes the first layer Each of the generation of free charge carriers in the second layer for injection into the layer and the termination of the generation is adapted to cause the switching between a conducting state and a blocking state. The advantage of such a device is that free charge carriers are generated more easily and at a very low cost by the smaller band cap in the second layer, i.e., instead of free charge carriers in the diamond. It means that a simpler device can be used than occurs. Another advantage is that such a device can optionally conduct with respect to a directional voltage or the same voltage applied across its terminals, simply by initiating or terminating the generation of the free charge carriers. States and blocking states can be assumed, so that the current in the determined direction can be switched on and off quickly without changing the direction of the voltage at all.
[0010]
According to another preferred aspect of the present invention, the means for generating free charge carriers irradiates the second layer with a photon beam having sufficient energy to generate free charge carriers in the second layer. Has been adapted to. This is one preferred possible means of generating free charge carriers in the second layer that allows very fast switching of the device.
[0011]
According to another preferred aspect of the present invention, the means comprises free charge by irradiating the second layer with electrons having a sufficiently high energy to generate free charge carriers in the second layer. It is adapted to generate carriers. This aspect also allows a very high switching frequency for rapid current interruption, the advantage being that it is easier to obtain free charge carriers faster than the previous aspect.
[0012]
According to another preferred aspect of the invention, the means for generating free charge carriers in the second layer does so by injecting free charge carriers into the second layer. Is provided. This is reliable and simple, and is therefore a preferred method for obtaining free charge carriers from an economic point of view and may be achieved by connecting a power supply to the second layer. .
[0013]
According to another preferred embodiment of the present invention, the device comprises two second layers separated by a first layer of diamond. Apart from the advantages of high breakdown field strength combined with good conductivity as described above, the device can optionally assume a blocking or conducting state regardless of the direction of the voltage applied across the terminals. It has advantageous features.
[0014]
According to another preferred embodiment of the invention, said means are adapted to supply free charge carriers in said second layer by doping. Thus, materials that are easier to dope than diamond are used in the second layer, and their excess electrons or holes conduct current through the diamond layer when the voltage has a “right” direction. This means that many negative potentials are applied to the terminal closest to the second layer when doped by a donor. This means that the device is blocked when a voltage is applied in a direction opposite to that in the conducting state. Thus, “free charge carrier supply” in separate dependent claims means that the charge carrier in question is always present there due to its doping, but is supplied for the movement if the voltage is not in the “right” direction. It includes cases where it is not done. This element functions as a rectifier diode.
[0015]
According to another preferred aspect of the present invention, the second layer is adjacent to at least a first layer made of crystalline SiC. This is advantageous for using SiC adjacent to the first layer for many purposes. An important advantage is that a clean interface between SiC and diamond is formed because an epitaxial interface is formed, thereby reducing the density of charge carriers trapped at the interface and thereby increasing mobility. Is easy. Another advantage is that the lattice match between SiC and diamond is relatively good, and SiC has a low thermal expansion coefficient so that such a structure stresses the interface layer resulting from temperature gradients and thermal cycling. It can withstand relatively high temperatures without the risk of damaging the interface as a result of the action of. This also means that diamond can benefit from the high temperature stability. Another advantage of using SiC in the second layer is that it is relatively easy to dope SiC if desired. SiC has a substantially smaller band gap than diamond, so that free charge carriers can easily be generated inside, for example, by irradiation with light or electrons.
[0016]
According to another preferred aspect of the invention, the second layer is a first thin sublayer made of SiC arranged between two sublayers, namely a first layer and a sublayer made of fairly thick Si. have. The technology for growing silicon is highly developed, and today, high quality silicon layers can be grown at high growth rates by using equipment that is cheaper than SiC. The advantage of using SiC adjacent to the diamond layer is mainly related to the high yield strength of SiC as well as the interface conditions, so that such a structure, in principle of operation, is that the entire second layer is made of SiC. It has the same advantageous features as if it were, but it is easier to manufacture it with the required quality. In practice, this structure is such that the carbon and Si atoms on the diamond layer automatically form SiC at the interface, so that Si is deposited on the intrinsic diamond layer, for example, by the use of Si chemical vapor deposition (CVD). The expression “by which the second layer is at least adjacent to the first layer of crystalline SiC” obtained by growing is defined to include this case. The thickness of this layer is adjusted in the heat treatment step. If the second layer is doped, the intended doping is performed very well outside the SiC layer.
[0017]
According to another preferable aspect of the present invention, the element has a layer adjacent to the first layer made of a semiconductor material between each terminal and the first layer, and the two layers made of the semiconductor material. Are mutually connected to conduct current by the movement of negative and positive charge carriers supplied in the layer of semiconductor material by the doping when a voltage is applied forward across the terminal. Doping is performed according to the opposite conductivity types n and p, respectively. So-called pin diodes with the most favorable opposite properties are obtained in this way. Therefore, the state of the element depends on the direction of the voltage applied between the terminals of the element.
[0018]
According to another preferred aspect of the invention, which constitutes a further development of the last mentioned aspect, the means is that when a voltage is applied between the terminals in the opposite direction, the voltage is between the terminals, Adapted to cause switching between a conducting state and a blocking state, respectively, by causing free charge carriers in the form of minority charge carriers to occur in at least one of said layers of semiconductor material and stopping this generation. ing. The possibility of generating free charge carriers in the form of fractional charge carriers in this way is always conducted when a voltage is applied in one direction and conducted or blocked when a voltage is applied in the other direction. In other words, an element that is selectively turned on or off is obtained. In some applications it is desirable to switch almost instantaneously between blocking and conducting states without changing any applied voltage, or in fault conditions this type of element for conduction. Are connected in parallel to quickly reduce the voltage across the element, and this type of device is suitable for such applications.
[0019]
According to another preferred aspect of the present invention, the first layer made of diamond has a substantially larger thickness than the other layers of the element. Since the diamond layer is adapted to take up most of the voltage across the element in its blocking state, the other layers may be made thinner.
Other advantages and advantageous features of the invention emerge from the following description and the dependent claims with reference to the accompanying drawings.
[0020]
(Brief description of the drawings)
A detailed description of preferred embodiments of the invention, cited by way of example, is given below with reference to the accompanying drawings.
FIG. 1 is a schematic longitudinal sectional view of a semiconductor device according to a first preferred embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of an element according to a second preferred embodiment of the present invention.
FIG. 3 is a graph showing ranges of a valence band and a conduction band in the element according to FIG.
FIG. 4 is a schematic longitudinal sectional view of an element according to a third preferred embodiment of the present invention.
FIG. 5 is a graph showing ranges of a valence band and a conduction band in the element according to FIG.
FIG. 6 is a schematic longitudinal sectional view of an element according to the fourth preferred embodiment of the present invention.
FIG. 7 is a schematic longitudinal sectional view of an element according to a fifth preferred embodiment of the present invention.
FIG. 8 is a schematic longitudinal sectional view of an element according to the sixth preferred embodiment of the present invention.
FIG. 9 is a graph showing ranges of the valence band and the conduction band in the element according to FIG.
FIG. 10 is a graph showing the relationship between the intensity and energy of irradiation with lattice lines in the element according to FIG.
FIG. 11 is a schematic longitudinal sectional view of an element according to a seventh preferred embodiment of the present invention.
[0021]
Detailed Description of the Preferred Embodiments of the Invention
A device according to a preferred embodiment of the invention is shown very schematically in FIG. This element has two terminals 1, 2 that connect the element to the current path. This element has a first layer 3 made of intrinsic diamond, which is usually 100 μm thick, on top of which a thin second material made of a semiconductor material, here crystalline SiC. Layer 4 is overlaid. The SiC layer 4 generally has a thickness of 1 μm to 10 μm. Metal contacts 5 and 6 connect the respective terminals to the diamond layer 3 and the SiC layer 4. The metal contact 6 has a hole that allows the incident line to pass through the surface 7 of the second layer 4 disposed below and into this layer. Features of the device that are not relevant to the invention, such as a passivation layer, have been omitted for clarity.
[0022]
The device irradiates the second layer 4 with photons or electrons having sufficient energy to generate free charge carriers in the second layer, thereby generating free charge carriers in the second layer 4. It also has the means indicated by the arrow 8 for generating. The SiC layer 4 is of any conceivable polytype, for example 6H, and the energy gap between the valence and conduction bands will vary with the polytype, but is generally about 3 eV. , Whereby light or electrons must have an energy of this value or slightly above this value in order to generate the free charge carriers. When the device is illuminated by photons or electrons and a voltage is applied across terminals 1 and 2, the device has a relatively low on-state voltage on the order of 10V (ie, due to carrier generation caused by irradiation). Free charge carriers that have become conductive and are generated in the second layer 4 are moved to the terminal 2 through the diamond layer 3 having high mobility, and the contact 5 is moved in the opposite direction toward the terminal 1. This is a so-called injection contact that generates charge carriers of opposite signs. This element is also called FTO (Fast Turn-Off Element) because it is interrupted within a few μs by terminating photon or electron irradiation and stopping the generation of free charge carriers in the second layer 4. . Therefore, this element can withstand a very high voltage of about 50 kV generated between the terminals 1 and 2 in the blocking state due to the extremely high breakdown field strength of diamond.
[0023]
FIG. 2 shows an element according to another preferred embodiment of the present invention. The element shown in FIG. 1 is different from the element shown in FIG. 1 in that two second layers 9 and 10 made of SiC are arranged on both sides of the diamond layer 3. The only difference is that one layer 9 is n-type (donor-doped) and the other layer 10 is p-type (acceptor-doped) due to radiation or electron bombardment. There is no means for generating free charge carriers. The doping concentration is generally 10 ¹⁷ -10 ¹⁹ cm ^-3 Examples of suitable donors are N and P, and examples of acceptors are B and Al.
[0024]
A band diagram of the device according to FIG. 2 is shown in FIG. In this figure, the upper limit extension of the valence band 11 and the extension of the lower limit of the conduction band 12 are shown from left to right through an n-type layer 9 made of SiC, a diamond layer 3 and a p-type layer 10 made of SiC. Yes. The Fermi level 13 indicated by the broken line is in the SiC layer 9 determined by the donor level and in the layer 10 determined by the acceptor level. The energy gap between the valence band and the conduction band in the SiC layer is slightly larger than half of the band gap of diamond and is about 3.2 eV (depending on polytype) for 5.4 eV. This means good alignment of the edges of the valence band 12 at the heterojunction between the diamond layer 3 and the p-type SiC layer 10, except for the small thin barrier 14 at the interface due to band bending, and the diamond layer 3 and n This results in a good alignment of the conduction band 11 at the heterojunction with the type SiC layer 9. The band bending effect can be minimized by diamond doping at the interface. This bandgap structure is important for devices of the type illustrated in FIG. 4 and illustrated by the energy band diagram of FIG. 2 becomes conductive when a negative potential is applied to terminal 1 and a positive potential is applied to terminal 2 and a voltage is applied between terminals 1 and 2, whereby electrons from layer 9 Moves through the diamond layer to the layer 10, the holes move in the opposite direction, and when the direction of the voltage applied between the terminals is changed, the element is blocked by the symbol rectifier diode 15. It is shown.
[0025]
The device shown in FIG. 4 has the means 16 adapted to generate free charge carriers in the p-type SiC layer 10 in the form of fractional charge carriers, ie electrons, in FIG. Different from the device shown. Said means 16 may be any type of voltage source capable of injecting electrons into the layer 10. The presence of these electrons 17 in the valence band and thereby active charge carriers is shown in FIG. Due to the tunneling effect through the barrier 14 and then through the diamond layer in the SiC layer 9 which creates a low voltage dropping from terminal 1 to terminal 2 and thus holes injected into the diamond layer to move in the opposite direction. In order to move the electrons 17 to the diamond layer 3, it is only necessary to apply a low voltage between the terminals 1 and 2 in the reverse direction of the “diode”. Thus, when a voltage is applied in the “reverse” direction to the device according to FIG. 4, the device is conductive as long as the means 16 injects free charge carriers in the form of electrons into the layer 10; When the fractional charge carrier injection is stopped, it switches to the blocking state. This switching process is very fast. Thus, the device has an equivalent structure 18 shown in FIG. 5, which is very useful in some high power applications.
[0026]
A device according to a fourth preferred embodiment of the invention is shown very schematically in FIG. 6, the main difference between this element and the element shown in FIGS. 9 and 10 are composed of two sublayers, that is, a thin first layer 19 made of crystalline SiC adjacent to the diamond layer 3 and a thicker layer 20 made of silicon disposed thereabove. . In this embodiment, a thin layer 19 made of SiC is utilized for the properties of SiC that form an interface with excellent properties in diamond, while a thicker layer made of Si is an interesting element from a constant growth rate and commercial point of view. Since a Si layer having a thickness larger than that of SiC can be grown considerably more easily under the conditions for manufacturing the substrate, it is provided on the upper surface. The SiC layer 19 may be as thin as a layer of one or several atoms resulting from the automatic deposition of Si atoms on the surface of the diamond layer.
[0027]
The element shown in FIG. 7 has the same main layer structure as the element shown in FIG. 4, but FIG. 7 also shows contact layers 5 and 6 on both sides. However, this device has another means 22 used for generating free charge carriers in the form of minority charge carriers in the SiC layers 9, 10. More precisely, this diamond-SiC-heterostructure diamond layer 3 is used as an optical conductor, and the intrinsic diamond layer is lateralized by photons scattered at the interface between the diamond layer and each SiC layer. Simultaneously with irradiation in the direction, free charge carriers are generated in the vicinity of the interface. This geometry ensures that all charge carriers occur near the interface. The energy of the photon is selected to be a value between the band gaps for SiC and diamond, ie, about 3 to 5.5 eV. Because these wavelengths can be generated more easily by lasers and other light sources than photons having a wavelength corresponding to at least 5.5 eV required to generate electron-hole pairs in diamond, There is an advantage that 3 eV is sufficient.
[0028]
FIG. 8 shows a so-called pin diode having the same general function as the diodes according to FIGS. 4 and 7, but as shown in FIG. The difference is that it is replaced by a p-type doped diamond layer 21 that is irradiated with photons 8 to generate minority charge carriers in the form of electrons. Layer 9 is an n-type doped SiC layer, but in practice may be any n-type doped semiconductor having a narrower band gap than diamond. The p-type doped diamond layer 21 and the n-type doped SiC layer 9 are grown on the intrinsic diamond substrate 3 by CVD, or the p-type diamond layer is formed by ion implantation of the acceptor into the intrinsic diamond substrate. It may be configured.
[0029]
The general function of this diode is the same as fully described by FIGS. 4 and 5, but with other means for generating free charge carriers. However, the device according to this embodiment has several important advantages. This diode may be optically driven by ultraviolet light penetrating the sample through the doped diamond surface 7. There are several difficulties associated with the absorption of ultraviolet light by the SiC layer, but these are reduced by using a p-type doped diamond layer, and thus, as in the embodiment according to FIG. There is no longer any need to irradiate the intrinsic layer. Furthermore, since only one heterojunction is formed, that is, between the intrinsic diamond and the n-type doping layer 9, the band bending effect is reduced and the manufacture is easy.
[0030]
This reverse-biased diode can be used as a light-driven switch. Under reverse bias, the diode blocks the current, but when illuminated with high intensity ultraviolet light, it becomes conductive due to the generation of charge carriers 17 in the intrinsic diamond layer. Such a device consisting of a sandwich structure of diamond and SiC layers functions to activate the switch because short wavelengths function to generate charge carriers in the diamond while at the same time long wavelengths generate carriers in the SiC layer. The power input in the form of ultraviolet light can be optimally used. Thus, the majority of the ultraviolet spectrum is used for charge carrier generation, as shown in FIG. 10, which is a graph of the relationship between ultraviolet intensity I and energy E. In FIG. 10, symbols a and b are lower limit values of charge carrier generation in SiC and diamond, that is, 3.2 eV and 5.4 eV, respectively. Thus, the portion indicated by arrow c can be used, and in the portion indicated by arrow d, charge carriers are efficiently generated in the diamond layer while avoiding SiC absorption problems.
[0031]
FIG. 11 shows that the element according to FIG. 2 is finely modified by arranging two second layers 9 and 10 and contacts 5 and 6 separated by the diamond layer 3 on the same side of the diamond layer 3. The element which consists of a thing is shown. This embodiment may of course be provided with any of the means for generating free charge carriers shown in FIGS. 1, 4 and 8 or any of the other means described above.
[0032]
The present invention is not limited to the above-described preferred embodiments, and those skilled in the art will make many modifications and changes without departing from the basic concept of the invention defined in the claims. Obviously you can.
[0033]
For example, the different embodiments shown in the above figures may be combined so that, for example, minority charge carriers in the device according to FIG. 4 may be generated by irradiation with light or electron bombardment of appropriate energy. The layers on both sides of the diamond layer in the embodiment according to FIGS. 2 and 4 may have the aspect according to FIG.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a semiconductor device according to a first preferred embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of an element according to a second preferred embodiment of the present invention.
3 is a graph showing ranges of a valence band and a conduction band in the device according to FIG.
FIG. 4 is a schematic longitudinal sectional view of an element according to a third preferred embodiment of the present invention.
5 is a graph showing ranges of a valence band and a conduction band in the element according to FIG.
FIG. 6 is a schematic longitudinal sectional view of an element according to a fourth preferred embodiment of the present invention.
FIG. 7 is a schematic longitudinal sectional view of an element according to a fifth preferred embodiment of the present invention.
FIG. 8 is a schematic longitudinal sectional view of an element according to a sixth preferred embodiment of the present invention.
9 is a graph showing ranges of a valence band and a conduction band in the element according to FIG.
10 is a graph showing the relationship between the intensity and energy of irradiation with lattice lines in the element according to FIG.
FIG. 11 is a schematic longitudinal sectional view of an element according to a seventh preferred embodiment of the present invention.

Claims (15)

Two terminals (1, 2), and when a voltage is applied between the terminals (1, 2), a conduction state that conducts current between these terminals (1, 2), and these terminals ( An element formed by connecting two terminals (1, 2) to each other by means of a material layer in order to switch between blocking states for preventing the movement of charge carriers between
The material layer comprises a first layer (3) made of intrinsic diamond and a second layer (4, 9, 10) disposed adjacent to the first layer (3),
Supplying free charge carriers to the second layer (4, 9, 10) to move through the first layer (3) by applying a voltage between the terminals (1, 2) To switch to the blocking state by stopping the supply of free charge carriers in the second layer (4, 9, 10) for movement in the first layer (3). The means (8, 16, 22)
The first layer (3) is adapted to receive a majority of the voltage applied between the terminals (1, 2) in the blocking state;
The second layer (4, 9, 10) is made of a material having an energy gap between a valence band and a conduction band substantially smaller than diamond, and the means (8, 16, 22) includes: For the injection into the first layer (3), the free charge carriers are generated substantially only in the second layer (4, 9, 10) to be in a conductive state and the generation is terminated. An element characterized in that it is adapted to switch to a blocking state respectively. The means (8) for supplying free charge carriers irradiates the second layer (4) with a photon beam having sufficient energy to generate free charge carriers in the second layer (4). The device of claim 1, wherein the device is adapted as follows. Said means (8), arising the free charge load carrier by irradiating the second layer by the electrons having a sufficiently high energy to rise to free charge carriers in the second layer (4) The device of claim 1, wherein the device is adapted as follows. As the the said free charge luggage carrier second layer (4, 10) means for supplying the (16), to supply free charge load carrier by injecting electrons into the second layer (10) The device according to claim 1, wherein the device is provided in the device. 5. A device according to claim 1, comprising two second layers (9, 10) separated by a first layer (3) of diamond. 6. Device according to claim 5, characterized in that both of the second layers (9, 10) are provided on the same side of the first layer (3) made of diamond. The second layer (9, 10) is, Ri crystal SiC Tona A device according to any one of claims 1 to claim 6, characterized in that it is disposed adjacent to the first layer. The second layer (9, 10) has two sublayers, namely, a second sublayer (20) made of Si, and between the second sublayer (20) and the first layer (3). 8. A device according to claim 7 , characterized in that it comprises a first sublayer (19) made of SiC which is thinner than the second sublayer (20). Two said second layer (9, 10) is made of a semiconductor material, the phase is respectively doped n-type and p-type a mutually opposite conductivity type,
Said means (8, 16, 22) for supplying free charge carriers provide free charge carriers in the form of minimum charge carriers in at least one of said second layers (9, 10) of said semiconductor material. By causing or stopping this occurrence, a conduction state and a blocking state can be obtained in a state in which a voltage is applied between the terminals such that the terminal (2) has a negative potential and the terminal (1) has a positive potential. 7. An element according to claim 5 or 6 , characterized in that it is adapted to cause switching between the two . It said second layer of semiconductor material (9, 10) is, crystal SiC Tona is, element according to claim 9, wherein it is adjacent to the first layer (3). 10. Device according to claim 9 , characterized in that one of the second layers (21) consists of p-doped diamond. A second layer (9) made of the semiconductor material adjacent to a side surface opposite to the second layer (21) made of the p-type doped diamond of the first layer (3); The device according to claim 11 , wherein the device is made of crystalline SiC. An interface between the first layer (3) and the second layer while the means (22) for supplying free charge carriers moves laterally in the first layer (3). By photons having sufficient energy to generate free charge carriers in the form of minority charge carriers in at least one of the second layers (9, 10) of semiconductor material near the interface. 10. Device according to claim 9 , characterized in that it is adapted to irradiate one layer (3) laterally. A first layer of the diamond (3), any one of claims 13 claim 1, characterized in that it has a substantially greater thickness than the second layer (4, 9, 10) The element as described in. 15. A device according to claim 14 , characterized in that the first layer (3) is configured to withstand voltages up to at least 5 kV in the blocking state.

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