semiconductor device

Abstract

A semiconductor device (100) comprising: a cathode (C); and an anode (A) comprising a first p-type semiconductor anode region (204) and a second p-type semiconductor anode region (206), wherein the first p-type semiconductor anode region (204) is electrically connected to an anode contact surface (218) and the second p-type semiconductor anode region (206) is electrically coupled to the anode contact surface (218) via a switch (S), and the switch (S) is suitable for establishing an electrical connection or an electrical separation between the second p-type semiconductor anode region (206) and the anode contact surface (218), and wherein the switch (S) comprises a field-effect transistor and the second p-type semiconductor anode region (206) is a source and drain element of the field-effect transistor,and the switch (S) has a first n-type auxiliary region (221) and a second p-type auxiliary region (230) laterally spaced from the first p-type semiconductor anode region (204), and the second p-type auxiliary region (230) represents the other element of the source and drain of the field-effect transistor, and wherein a dose of the p-type doping in the first p-type semiconductor anode region (204) is smaller than the dose of the p-type doping in the second p-type semiconductor anode region (206), and wherein the second p-type semiconductor anode region (206) can be connected to the first p-type semiconductor anode region (204) in the forward direction between the anode (A) and the cathode (C) by switching on the switch (S).

Description

BACKGROUNDSemiconductor diodes are widely used in semiconductor applications. In semiconductor converter applications, for example, the correlation between the reverse recovery behavior and the turn-on characteristic of a freewheeling diode has an influence on the converter properties. Exemplary semiconductor diodes are described in the publications U.S. Pat. No. 5,969,400 A, DE 10 2009 029 691 A1, JP H09-107 097 A, JP H06-77 506 A and DE 10 2005 019 860 A1.It is an object of the invention to improve the interrelationship, i.e., mutual matching, between the reverse recovery behavior and the turn-on behavior of a diode.The object is achieved by the teaching of the independent patent claims. Further developments are the subject matter of the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 shows a schematic illustration of an embodiment of a diode having a first anode and a second anode, wherein the second anode can be switched on and off by means of a switch. FIG. 2 shows a cross-section of a portion of an embodiment of a diode having a first anode and a second anode, wherein the second anode is connectable and disconnectable with a field effect transistor (FET). FIG. 3 is a schematic diagram of a p-type doping profile along a line A-A' (B-B') of the first anode (second anode) shown in FIG. 2. FIG. 4 shows a cross-section of a portion of another embodiment of a diode having a first anode and a second anode, wherein the first anode is positioned opposite a first portion of a cathode and the first portion of the cathode has a smaller average n-type dopant concentration than a second portion of the cathode opposite the second anode. FIG. 5 shows a schematic diagram of an embodiment of an n-type doping profile along a line C-C' (D-D') of the first cathode region (second cathode region) shown in FIG. 4. FIG. 6 shows a cross section of a portion of a further embodiment of a diode having a first anode and a second anode, wherein the second anode is switchable on and off via a gate of an FET extending along a channel direction into a region above an n-type drift zone. FIG. 7A shows a cross section of a region of a further embodiment of a diode having a first anode adjoining a trench isolation and a second anode, wherein the second anode can be switched on and off by a trench FET. FIG. 7B shows a cross section of a region of a further embodiment of a diode having a first anode adjoining a trench isolation and a second anode which can be switched on and off with a trench FET, wherein the gate electrode of the trench FET extends deeper into an n-type drift zone than the second anode. FIG. 8A shows a cross section of a portion of a further embodiment of a diode having a first anode and a second anode, wherein the second anode can be switched on and off with a trench FET. FIG. 8B shows a cross section of a portion of a further embodiment of a diode having a first anode and a second anode which can be switched on and off with a trench FET, wherein the gate electrode of the trench FET extends deeper into an n-type drift zone than the second anode. FIG. 9 shows a cross section of a portion of another embodiment of a diode having a first anode and a second anode, wherein the first anode is part of a merged PIN Schottky diode. FIG. 10 shows a schematic view of an embodiment of a diode having a first cathode and a second cathode, wherein the second cathode can be switched on and off by means of a switch.DETAILED DESCRIPTIONFIG. 1 shows a schematic view of an embodiment of a diode 100 having an anode A and a cathode C. The anode A comprises a first anode A 1 and a second anode A 2. The first anode A 1 is electrically connected to an anode contact (not shown in FIG. 1 ). The second anode A 2 is electrically coupled to the anode contact via a switch S, wherein the switch S is suitable for establishing an electrical connection or an electrical disconnection between the second anode A 2 and the anode contact.The switch S may be any device capable of switching between an on state, i.e., a conductive state, and an off state, i.e., a non-conductive state. For example, the switch S may include a transistor such as an FET or a bipolar transistor.According to an embodiment, the switch S may be at least partially formed in an active region of the diode 100. For example, the second anode A 2 may include a semiconductor region common to both the diode 100 and the switch S, e.g., a p-type semiconductor region constituting the second anode, and a source and drain (emitter and collector) element of an FET (bipolar transistor). According to another embodiment, the switch S may be formed in an active region different from the active region of the diode 100. For example, the second anode A may be electrically coupled in 2 with the switch S via contact plugs and / or wiring, and the switch S may be electrically coupled with the anode contact via other contact plugs and / or other wiring. The cathode C comprises a cathode contact, e.g. a metallic region, common to both the first anode A 1 and the second anode A 2.When the switch S is in an on state, e.g., a conductive state, the anode A contributes 2 to the current flow between the anode A and the cathode C. If the switch S is in an off state, current flow between the cathode C and the second anode A 2 is suppressed. Anode efficiency is set higher in the second anode A 2 than in the first anode A 1, by appropriately selecting anode parameters having an influence on the efficiency, such as dopant dose, e.g., dopant concentration and vertical extension of the doping or minority carrier lifetime in the anode A. The diode 100 can block voltage in the on and off state of the switch S. While the diode 100 is operated in a so-called high-speed mode (high speed mode) with a low charge carrier concentration and thus an advantageous delay behavior when the switch S is switched off and with the second anode A 2 switched off, the diode 100 operates in a so-called low saturation mode (low saturation mode) with a high charge carrier concentration and a low on-resistance when the switch S is switched on and with the second anode A 2. switched on. While the off state of the switch S enables a better reverse recovery characteristic of the diode 100, the on switch S enables a better on characteristic of the diode 100. Thus, by switching between the on and off states of the switch S depending on the operation state of the diode 100, the mutual matching between the reverse recovery characteristic and the on characteristic of the diode 100 can be improved.FIG. 2 shows a cross-section of a portion of an embodiment of a diode 200. The diode 200 comprises an n-type drift zone 202 such as an n-type semiconductor substrate, e.g. an Si substrate having no, one or a plurality of semiconductor layers formed thereon such as epitaxial layers. A first p-type anode region 204 and a second p-type anode region 206 are formed within the n-type drift zone 202, wherein both regions adjoin a first side 208 of the n-type drift zone 202. A bottom side of the second p-type anode region 206 is located deeper within the n-type drift zone 202 than the bottom side of the first p-type anode region 204, i.e. an extension d 2 of the second p-type anode region 206 along a vertical direction 210 from the first side 208 into the n-type drift zone 202 is larger than the corresponding extension d 1 of the first p-type anode region 204. A lateral direction 211 runs parallel to the first side 208 and perpendicular to the vertical direction 210.An n-type cathode region 212 adjoins the n-type drift zone 202 on a second side 214 of the n-type drift zone 202. The n-type cathode region 212 is common to the first p-type anode region 204 and the second p-type anode region 206. A cathode contact 216, such as a metal or metal compound, is adjacent to the n-type cathode region 212.The first p-type anode region 204 is electrically connected to an anode contact 218 on the first side 208. The anode contact 208 may include one or a plurality of contact plugs and / or one or more wirings.The second p-type anode region 206 is electrically coupled to the anode contact 218 via an FET 220. The FET 220 includes the p-type anode region 206 as one of the source and the drain. An n-type region 221 is formed within the p-type anode region 206 and is adjacent to the first side 208. A channel 222 is disposed on the first side 208 within the n-type region 221. A conductivity of the channel 222 is controllable via a gate structure 224 above the channel 222. The gate structure 224 includes a gate dielectric 226, e.g. SiO 2, and a gate electrode 228, e.g. a conductive or semiconducting material such as a metal, a metal compound or a doped semiconductor. A p-type region 230 represents the other of the source and drain of the FET 220, is disposed in the n-type region 221 and is adjacent to the first side 208. Current flow between source and drain of the FET 220 is controllable along the lateral direction 211 at the first side 208 between the second p-type anode region 206 as the one of source and drain and the p-type region 230 as the other of source and drain by applying a corresponding voltage to the gate electrode 228. Thus, the reverse recovery behavior as well as the turn-on characteristics of the diode may be affected by turning on and off the second p-type anode region 206 with the FET 220. As a result, the mutual coordination between the reverse recovery behavior and the turn-on behavior can be improved.The doping and vertical dimensions of the first and second p-type anode regions 204, 206 may be different from the embodiment shown in FIG. 2. The dose of doping of the second p-type anode region 206 may be set larger than the dose of doping of the first p-type anode region 204 by, e.g., setting a depth of the p-type anode region 204 in the n-type drift zone 202 larger than the depth of the second p-type anode region 206, which is associated with a corresponding increase of the dopant concentration in the second p-type anode region 206. A ratio of dopant doses between the second p-type anode region 206 and the first p-type anode region 204 may be between 5 and 10 4, or 5 to 10 3 or 5 to 10 2 for example.FIG. 3 shows a schematic illustration of an embodiment of a dopant profile N 1( N 2) of p-type impurities along a line A-A' (B-B') in the first p-type anode region 204 (second p-type anode region 206) of FIG. 2.The concentration N 1 of the p-type doping in the first p-type anode region 204 of FIG. 2 is smaller than the concentration N 2 of the p-type doping in the second p-type anode region 206. Thereby, the anode efficiency of the second p-type anode region 206 may be set to be greater than the anode efficiency in the first p-type anode region 204. The concentration profiles N 1, N 2 can be suitably adjusted, for example by suitably selecting implantation parameters such as energy and dose.FIG. 4 shows a cross-section of a portion of a diode 400 according to another embodiment that is similar to the diode 200 shown in FIG. 2. However, the diode 400 differs from the diode 200 by a second n-type cathode region 434 in addition to the n-type cathode region 412. The second n-type cathode region 434 is disposed opposite the second p-type anode region 406, but is absent from a region opposite the first p-type anode region 404. In addition, the second n-type cathode region 434 extends deeper into the n-type drift zone 402 than the n-type cathode region 412, i.e. an extension d 4 of the second n-type cathode region 434 along the vertical direction 410 from the second side 414 into the n-type drift zone 402 is greater than the corresponding extension d 3 of the n-type cathode region 412. As a result, the cathode efficiency can be set to be greater in a region opposite the second p-type anode region 406 than in a region opposite the first p-type anode region 404. For example, d 4 may be set to be larger than d 3, for example, by appropriately selecting implantation parameters such as the implantation energy.FIG. 5 is a schematic diagram of a profile of concentration N 3( N 4) of n-type impurities along a line C-C' (D-D') of the n-type cathode region 412 shown in FIG. 4 (second n-type cathode region 434), according to an embodiment.The concentration N 3 of the n-type impurities in the n-type cathode region 412 of FIG. 4 is less than the concentration N 4 of the n-type impurities in the second n-type cathode region 434. As a result, the cathode efficiency can be set to be greater in a region opposite the second p-type anode region 406 than in a region opposite the first p-type anode region 404. The profiles of the concentrations N 3, N 4 can be adjusted, for example, by suitable selection of implantation parameters such as energy and dose.FIG. 6 shows a cross-section of a portion of another embodiment of a diode 600 similar to diode 200 shown in FIG. 2. However, the diode 600 is different from the diode 200 in terms of the dimensions of the gate structure 624. While a lateral extension of the gate structure 224 of the diode 200 shown in FIG. 2 ends above the second p-type anode region 206, the corresponding lateral dimension of the gate structure 624 of the diode 600 in FIG. 6 ends above the n-type drift zone 602. This distinguishing feature enables the technical effect of further reducing the charge carrier concentration in the n-type drift zone 602 when the diode 600 is operating in a unipolar mode without reverse bias capability. In this unipolar mode, a positive voltage is applied to the gate electrode 628 to enable electron current along a channel between the n-type drift 602 and the n-type region 621 at the first side 608. It is thus possible to reduce the carrier concentration within the n-type drift zone 602 and to operate the diode 600 at a very high speed. However, before the operation continues with the reverse recovery, the diode 600 must return to an operation mode having a voltage blocking capability, for example, by changing the voltage applied to the gate electrode 628.FIG. 7A shows a cross-section of a portion of a diode 700 according to another embodiment. The diode 700 differs from the diode 200 shown in FIG. 2 in that the first p-type anode region 704 laterally adjoins a trench isolation 738 extending from the first side 708 into the drift zone 702 along the vertical direction 710. The trench isolation 738 may be formed by etching a trench into the n-type drift zone 702, e.g. by an etching process such as a dry etch, followed by filling the trench with an electrically insulating material such as an oxide of the silicon. In the embodiment of FIG. 7A, the trench isolation 738 extends deeper into the n-type drift zone 702 than the first p-type anode region 704, i.e., a bottom side of the trench isolation 738 lies below the bottom side of the first p-type anode region 704. According to further embodiments, a bottom side of the trench isolation 738 may be just as above or at the same height as the bottom side of the first p-type anode region 704.Diode 700 also differs from diode 200 shown in FIG. 2 in that FET 720 is a vertical channel trench FET and not a lateral channel FET like FET 220. The gate structure 724 of the FET 720 includes a gate electrode 728 and a dielectric 726 within a trench. Lateral sides of each second p-type anode region 706, which represents one electrode of source and drain, the n-type region 721 comprising a channel 722, and the p-type region 730 representing the other element of source and drain, adjoin the gate structure 724. The conductivity of the channel 722 is controllable by the voltage applied to the gate electrode 728.FIG. 7B shows a cross-section of a portion of a diode 700' according to another embodiment, wherein the diode 700' is similar to the diode 700 shown in FIG. 7A.The diode 700' of FIG. 7B differs from the diode 700 in FIG. 7A in that the gate electrode 728' extends deeper into the n-type drift zone 702 than the second p-type anode region 706, i.e. a bottom side of the gate electrode 728' is arranged below the bottom side of the second p-type anode region 706. In other words, a depth d 5 of a bottom side of the gate electrode 728' to the first side 708 is greater than the depth d 6 of the bottom side of the second p-type anode region 706 to the first side 708.Similar to the gate electrode 628 of the planar FET 620 shown in FIG. 6, the gate electrode 728' enables the technical effect of a further reduction of the charge carrier concentration in the n-type drift zone 702 when the diode 700' is operated in a unipolar mode without reverse voltage blocking capability. In this unipolar mode, a positive voltage is applied to the gate electrode 728' to allow electron current along a vertical channel between the n-type drift zone 702 and the n-type region 721 at a sidewall of the trench. It is thus possible to reduce the carrier concentration within the n-type drift zone 702 and to operate the diode 700' at very high speed. However, before operation continues with the reverse recovery, diode 700' must return to a voltage blocking capability mode of operation, e.g., by changing the voltage applied to gate electrode 728'.FIG. 8A shows a cross-section of a portion of a diode 800 according to another embodiment, wherein the diode 800 is similar to the diode 700 shown in FIG. 7A.Diode 800 differs from diode 700 in FIG. 7A in that its trench isolations adjacent to first p-type anode region 804 are absent. Instead, the p-type anode region 804 is surrounded by the n-type drift zone 802, similar to the embodiments shown in FIGS. 2, 4 and 6.FIG. 8B shows a cross-section of a portion of a diode 800' according to another embodiment, wherein the diode 800' is similar to the diode 800 shown in FIG. 8A.The diode 800' in FIG. 8B differs from the diode 800 shown in FIG. 8A in that the gate electrode 828' extends deeper into the n-type drift zone 802 than the second p-type anode region 806, i.e. a bottom side of the gate electrode 828' is deeper than the bottom side of the second p-type anode region 806. In other words, a depth d 5 at the bottom of the gate electrode 828' to the first side 808 is greater than the depth d 6 of the bottom of the second p-type anode region 806 to the first side 808. With regard to the technical effect associated with the arrangement of the gate electrode 828, reference is made to the gate electrode 728' shown in FIG. 7B and the associated description further above.According to further embodiments, the diode may comprise a lateral channel FET and a p-type anode region laterally adjacent to a trench isolation.The arrangement of trench isolation adjacent to the first p-type anode region enables a reduction of the emitter efficiency in this region. If the switch is formed as a trench FET, the channel conductivity can be improved.FIG. 9 shows a cross section of a portion of a diode 900 according to another embodiment, wherein the diode 900 comprises a cathode contact 916, an n-type cathode region 912, an n-type drift zone 902 and a second p-type anode region 906 similar to the diodes 200, 400 and 600 in FIGS. 2, 4 and 6. The first p-type anode regions 904, 904' are part of a merged PIN Schottky diode. The merged PIN Schottky diode also has a Schottky junction between a metal contact 942 on the first side 908 and the n-type drift zone 902 adjoining the latter. The metal contact 942 may be part of or electrically connected to a first anode contact 918 of the diode 900. The metal contact 942 also electrically connects to the first p-type anode regions 904, 904'. Thus, the first p-type anode regions 904, 904' and the metal contact 942 in the merged PIN Schottky diode constitute the anode.A switch S establishes an electrical connection or electrical separation between the second p-type anode region 906 and the anode contact 918. According to an embodiment, the switch S may be at least partially formed in an active region of the diode 900. According to another embodiment, the switch S may be formed in an active region different from the active region of the diode. Unlike the second anode region 906, the anode of the merged PIN Schottky diode may be turned on and off via the switch S. Since the merged PIN Schottky diode allows a reduction in emitter efficiency, the difference in efficiency of the diode 900 between the switch S open and switch S closed operating mode can be further increased, i.e., the difference in carrier concentration between the switch S open and switch S closed operating mode can be further increased.According to further embodiments, the conductivity types of the described semiconductor regions may be interchanged. Thus, an anode described above would correspond to a cathode and a cathode described above would correspond to an anode. This case is shown schematically in Fig. 10. In the embodiment shown in FIG. 10, a diode 100' includes an anode A and a cathode C. The cathode C includes a first cathode C1 and a second cathode C2. The first cathode C 1 is electrically connected to a cathode contact (not shown in FIG. 10 ). The second cathode C 2 is electrically coupled to the cathode contact C 2 via a switch S, wherein the switch S is suitable for establishing an electrical connection or an electrical disconnection between the second cathode C 2 and the cathode contact.The embodiments shown above in Figs. 2 to 9 also apply to the diode 100' by exchanging anode and cathode, and n- and p-type.Terms with relative spatial reference such as "under", "below", "lower", "over", "above" and the like serve to simplify the description of the positioning of an element relative to a second element. These terms are intended to encompass different orientations of the device in addition to the orientations shown in the figures. In addition, the terms "first", "second", and the like are used to describe various elements, regions, portions, and are also not limiting. Similar terms are used to describe similar elements in this description.Terms such as "comprise", "contain", "have" and similar terms are open terms, i.e. other elements may be present in addition to the "comprise" elements. Elements identified with certain and indeterminate terms may be in the singular or plural form unless expressly identified otherwise.As used herein, the term "electrically coupled" includes, in addition to directly coupling the elements involved, indirect coupling via intervening elements.The term "active region" refers to a semiconductor region of a device that is separated from semiconductor regions of other regions, such as by an isolation such as trench or pn junction isolation.As used herein, the term "dopant dose" of a particular conductivity type, e.g., n-type p-type, refers to the number of dopants of that conductivity type that are introduced into a semiconductor body such as a drift zone per unit area by a suitable method such as ion implantation.The elements described in the various embodiments may be combined with each other as desired unless they are mutually exclusive. Similar reference numerals are used to designate similar elements.

Claims

A semiconductor device (100) comprising: a cathode (C); and an anode (A) having a first p-type semiconductor anode region (204) and a second p-type semiconductor anode region (206), wherein the first p-type semiconductor anode region (204) is electrically connected to an anode pad (218) and the second p-type semiconductor anode region (206) is electrically coupled to the anode pad (218) via a switch (S), and the switch (S) is adapted to establish an electrical connection or electrical disconnection between the second p-type semiconductor anode region (206) and the anode pad (218), and wherein the switch (S) comprises a field effect transistor and the second p-type semiconductor anode region (206) is an element of the source and drain of the field effect transistor, and the switch (S) has a first n-type auxiliary region (221) and a second p-type auxiliary region (230) laterally spaced apart from the first p-type semiconductor anode region (204), and the second p-type auxiliary region (230) represents the other element of the source and drain of the field effect transistor, and wherein a dose of the p-type doping in the first p-type semiconductor anode region (204) is less than the dose of the p-type doping in the second p-type semiconductor anode region (206), and wherein the second p-type semiconductor anode region (206) can be connected to the first p-type semiconductor anode region (204) in the direction of flow between anode (A) and cathode (C) by switching on the switch (S).The semiconductor device of claim 1, wherein an n-type dopant dose in a first region of the cathode (C) opposite the first p-type semiconductor anode region (404) is less than the n-type dopant dose in a second region of the cathode (C) opposite the second p-type semiconductor anode region (406).The semiconductor device according to claim 2, wherein a ratio of the dose of the n-type doping in the second region of the cathode (C) to the dose of the n-type doping in the first region of the cathode (C) is between 5 and 10 4.The semiconductor device of any preceding claim, wherein a ratio of the doses of the p-type doping in the second p-type semiconductor anode region (206) to the dose of the p-type doping in the first p-type semiconductor anode region (204) is between 5 and 10 4.The semiconductor device of any of the preceding claims, wherein a bottom surface of the second p-type semiconductor anode region (206) is deeper within a semiconductor substrate than a bottom surface of the first p-type semiconductor region (204).The semiconductor device of any preceding claim, further comprising: an n-type drift zone (202) disposed between the first p-type semiconductor anode region (204) and the second p-type semiconductor anode region (206), and between the cathode (C) and the anode (A).The semiconductor device of any preceding claim, wherein the first p-type semiconductor anode region (904) is a part of a merged pin Schottky diode.The semiconductor device according to claim 1, wherein the switch (S) is a planar field effect transistor having a lateral channel or a trench field effect transistor having a vertical channel.The semiconductor device of claim 1, wherein the first n-type auxiliary region (221) and the second p-type auxiliary region (230) are electrically connected to the anode pad (218).The semiconductor device of claim 1 or 9, wherein: the switch (S) is a planar field effect transistor having a lateral channel; the first n-type auxiliary region (221) is disposed in the second p-type semiconductor anode region (206); the second p-type auxiliary region (230) is disposed in the first n-type auxiliary region (221); the second p-type semiconductor anode region (206), the first n-type auxiliary region (221), and the second p-type auxiliary region (230) are each adjacent to a surface (208) of a semiconductor substrate; and a gate (220) arranged above the first n-type auxiliary region (221), the gate being suitable for controlling a conductivity of a channel arranged in the first n-type auxiliary region (221) at the surface (208) between the second p-type auxiliary region (230) and the second p-type semiconductor anode region (206).The semiconductor device of claim 10, wherein an extension of the gate (220) along a channel direction parallel to the surface (208) between the source and the drain of the planar field effect transistor terminates over the second p-type semiconductor anode region (206).The semiconductor device of claim 10, wherein an extension of the gate (620) along a channel direction parallel to the surface (608) between the source and the drain of the planar field effect transistor terminates above an n-type drift zone (602).The semiconductor device according to any one of the preceding claims, wherein a blocking capability between the anode (A) and the cathode (C) is between 0.6 kV and 10 kV.The semiconductor device of claim 9, wherein: the switch (S) is a trench field effect transistor having a vertical channel; the first n-type auxiliary region (721) is disposed in the second p-type semiconductor anode region (706); the second p-type auxiliary region (730) is disposed in the first n-type auxiliary region (721); the first n-type auxiliary region (721) and the second p-type auxiliary region (730) are adjacent to a surface (708) of a semiconductor substrate; and a gate electrode (728) arranged within a trench, wherein the gate electrode (728) is adapted to control the conductivity of a channel arranged in the first n-type auxiliary region (721) at a sidewall of the trench between the second p-type auxiliary region (730) and the second p-type semiconductor anode region (706).The semiconductor device of claim 14, wherein a bottom surface of the gate electrode (728) terminates deeper within the semiconductor substrate than a bottom surface of the second p-type anode region (706).The semiconductor device of claim 14, wherein a bottom surface of the gate electrode (728) terminates within the semiconductor substrate at a same depth or below a bottom surface of the second p-type anode region (706).The semiconductor device of claim 14, wherein the first p-type semiconductor anode region (704) is adjacent to a trench isolation (738).The semiconductor device of any preceding claim, wherein a minority carrier lifetime is greater in the second p-type semiconductor anode region (206) than in the first p-type semiconductor anode region (204).The semiconductor device of claim 18, wherein a ratio of the minority carrier lifetime in the second p-type semiconductor anode region (206) to the minority carrier lifetime in the first p-type semiconductor anode region (204) is between 5 to 10 4.A semiconductor device (100) comprising: an anode (A); and a cathode (C) having a first n-type semiconductor cathode region and a second n-type semiconductor cathode region, wherein the first n-type semiconductor cathode region is electrically connected to a cathode pad and the second n-type semiconductor cathode region is electrically coupled to the cathode pad via a switch (S), wherein the switch (S) is adapted to establish an electrical connection or electrical disconnection between the second n-type semiconductor cathode region and the cathode pad, and wherein the switch (S) comprises a field effect transistor and the second n-type semiconductor cathode region is one of a source and a drain of the field effect transistor, and the switch (S) has a first p-type auxiliary region and a second n-type auxiliary region laterally spaced apart from the first n-type semiconductor cathode region, and the second n-type auxiliary region represents the other element of the source and drain of the field effect transistor, and wherein a dose of the n-type doping in the first n-type semiconductor cathode region is smaller than the dose of the n-type doping in the second n-type semiconductor cathode region, and wherein the second n-type semiconductor cathode region can be added to the first n-type semiconductor cathode region in the direction of flow between anode (A) and cathode (C) by switching on the switch (S).A semiconductor device (100) comprising: a cathode (C); and an anode (A) having a first p-type semiconductor anode region (204) and a second p-type semiconductor anode region (206), wherein the first p-type semiconductor anode region (204) is electrically connected to an anode pad (218) and the second p-type semiconductor anode region (206) is electrically coupled to the anode pad (218) via a switch (S), and the switch (S) is adapted to establish an electrical connection or electrical disconnection between the second p-type semiconductor anode region (206) and the anode pad (218), and wherein an n-type dopant dose in a first region of the cathode (C) opposite the first p-type semiconductor anode region (404) is less than the n-type dopant dose in a second region of the cathode (C) opposite the second p-type semiconductor anode region (406).A semiconductor device (100) comprising: an anode (A); and a cathode (C) comprising a first n-type semiconductor cathode region and a second n-type semiconductor cathode region, wherein the first n-type semiconductor cathode region is electrically connected to a cathode contact pad and the second n-type semiconductor cathode region is electrically coupled to the cathode contact pad via a switch (S), and the switch (S) is suitable for establishing an electrical connection or an electrical separation between the second n-type semiconductor cathode region and the cathode contact pad, and wherein a p-type dopant dose in a first region of the anode (A) opposite the first n-type semiconductor cathode region is smaller than the p-type dopant dose in a second region of the anode (A) opposite the second n-type semiconductor cathode region.

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