DE102023101018A1 - OPTOELECTRONIC SEMICONDUCTOR CHIP AND METHOD FOR PRODUCING AN OPTOELECTRONIC SEMICONDUCTOR CHIP - Google Patents

Abstract

The invention relates to an optoelectronic semiconductor chip, having an active zone with a pn junction for generating electromagnetic radiation, a photonic crystal, a contacting layer adjacent to the photonic crystal, a first contact structure and a second contact structure. The photonic crystal is arranged between the active zone and the contacting layer. The first contact structure is electrically conductively connected to a first side of the active zone via the contacting layer. The second contact structure is electrically conductively connected to a second side of the active zone. The photonic crystal has a periodic structure consisting of at least a first material with a first refractive index and a second material with a second refractive index. The first material has periodically arranged recesses that are at least partially filled with the second material. The first refractive index is greater than the second refractive index.

Description

The present invention relates to an optoelectronic semiconductor chip and a method for producing an optoelectronic semiconductor chip.

Optoelectronic semiconductor chips are known in the prior art in which light generated in an active zone is coupled out via a photonic crystal. These can be laser diodes, for example. Such optoelectronic semiconductor chips can be referred to as PCSELs (Photonic Crystal Surface-emitting Lasers). In the photonic crystal, a first material with air-filled recesses is used to guide laser radiation and thus specify an emission direction of the optoelectronic semiconductor chip. The problem with these optoelectronic semiconductor chips is that the photonic crystal must be electrically conductively contacted so that an electrical voltage can be applied to the active zone. This contact partially fills the recesses, so that the photonic crystal may not work properly.

One object of the present invention is to provide an improved optoelectronic semiconductor chip. Another object of the present invention is to specify a method for producing the optoelectronic semiconductor chip. These objects are achieved by an optoelectronic semiconductor chip and by a method for producing an optoelectronic semiconductor chip with the features of the independent claims. Advantageous further developments are specified in the dependent claims.

A first aspect of the invention relates to an optoelectronic semiconductor chip, having an active zone with a pn junction for generating electromagnetic radiation, a photonic crystal, a contacting layer adjacent to the photonic crystal, a first contact structure and a second contact structure. The optoelectronic semiconductor chip can be a laser diode. In this case, laser radiation can be generated in the active zone. The photonic crystal is arranged between the active zone and the contacting layer. The first contact structure is electrically conductively connected to a first side of the active zone via the contacting layer. The second contact structure is electrically conductively connected to a second side of the active zone. An electrical voltage can thus be applied to the active zone via the first contact structure and the second contact structure, which is necessary for generating the electromagnetic radiation emitted by the optoelectronic semiconductor chip, in particular laser radiation. The photonic crystal has a periodic structure consisting of at least a first material with a first refractive index and a second material with a second refractive index. The first material has periodically arranged recesses which are at least partially filled with the second material. The first refractive index is greater than the second refractive index.

The first material and/or the second material can comprise a dielectric. It can be provided that the first material and/or the contact layer comprise a doped semiconductor material. Both the first material and the second material can have a solid state of aggregation. The second material can also be arranged exclusively in the recesses. It can also be provided that the recesses are completely filled with the second material.

Because the photonic crystal has the second material, which is at least partially arranged in the recesses of the first material, the optoelectronic semiconductor chip is easier to manufacture, since the second material can close the recesses and thus applying the contact layer is easier. In particular, when applying the contact layer, it can be prevented that a material of the contact layer gets into the recesses. The greater the difference between the first refractive index and the second refractive index, the better suited the photonic crystal is for the optoelectronic semiconductor chip.

Such an optoelectronic semiconductor chip can be designed as a PCSEL (photonic crystal surface-emitting laser). In particular, a single laser mode can then be excited and thus the emission power of this individual laser mode can be maximized.

A second aspect of the invention relates to a method for producing an optoelectronic semiconductor chip, in particular the optoelectronic semiconductor chip according to the first aspect of the invention. In this method, an active zone with a pn junction can first be provided. A photonic crystal is then applied to the active zone. The photonic crystal has a periodic structure consisting of at least a first material with a first refractive index and a second material with a second refractive index. The first material has periodically arranged recesses which are at least partially filled with the second material. The first refractive index is greater than the second refractive index. A contacting layer is then applied to the photonic crystal in such a way that the photonic crystal is arranged between the active zone and the contacting layer. Furthermore, in the method, a first contact structure is applied in such a way that the first contact structure is electrically conductively connected to a first side of the active zone via the contacting layer and a second contact structure is applied in such a way that the second contact structure is electrically conductively connected to a second side of the active zone.

In one embodiment of the optoelectronic semiconductor chip, the recesses on a first crystal side facing away from the active zone are closed by the second material. A closed surface made of first material and second material is therefore arranged on the first crystal side. This enables a defined structure of the photonic crystal.

In one embodiment of the optoelectronic semiconductor chip, the recesses have a cavity on a second crystal side facing the active zone. The cavity can in particular be closed with the second material on the first crystal side.

In one embodiment of the optoelectronic semiconductor chip, the cavity is filled with a gas. The gas can have a third refractive index close to 1, so that a difference between the first refractive index and the third refractive index is as large as possible, so that an efficient photonic crystal can be provided. If this is combined with the closure of the recess with the second material on the first crystal side, it can be achieved in particular that the contacting layer can be applied to the photonic crystal without material of the contacting layer getting into the recesses.

In one embodiment of the optoelectronic semiconductor chip, the recess is rotationally symmetrical. The second material has a cylindrical or frustoconical basic structure, wherein the second material has a conical recess facing the cavity. A second material designed in this way can be produced by applying the second material in a preferred direction, wherein the active zone and the first material are at an angle to the preferred direction, for example at an angle between 30 and 80 degrees. The active zone and the first material are rotated while the second material is being applied. This makes it possible to close the recesses with the second material and to create the largest possible cavity.

In one embodiment of the optoelectronic semiconductor chip, the first material comprises a III-V semiconductor material, for example based on gallium nitride (GaN). Other alloys, for example made from different elements of group III or group V of the periodic table of elements, can also be used.

In one embodiment of the optoelectronic semiconductor chip, the second material comprises silicon dioxide (SiO2) and/or magnesium fluoride (MgF2) and/or calcium fluoride (CaF2). These materials have a low second refractive index compared to typical semiconductor materials that can be used as the first material. This results in an efficient photonic crystal.

In one embodiment of the optoelectronic semiconductor chip, the photonic crystal adjoins the active zone. In particular, the photonic crystal can be grown directly on the active zone. Alternatively, a conductive intermediate layer can also be provided. A distance between the active zone and the photonic crystal can be selected based on an emission wavelength of the optoelectronic semiconductor chip.

In one embodiment of the optoelectronic semiconductor chip, the active zone has a first region with a first doping and a second region with a second doping. The first region and the second region form the pn junction. At least one quantum well is arranged in the first region. In particular, several quantum wells can also be arranged. This enables a simple construction of the optoelectronic semiconductor chip.

In one embodiment of the optoelectronic semiconductor chip, the first region has at least one p-doped GaN quantum well, in particular a plurality of p-doped GaN quantum wells. In this case, the first material can also have p-doped GaN. In one embodiment of the optoelectronic semiconductor chip, the second region has an n-doped GaN substrate. The pn junction of the active zone is formed by the p-doped GaN quantum well or the p-doped GaN quantum wells and the n-doped GaN substrate, wherein a wavelength of the optoelectronic semiconductor chip can be set by the dimensions of the p-doped GaN quantum well or the p-doped GaN quantum wells.

In one embodiment of the optoelectronic semiconductor chip, the contacting layer is transparent to electromagnetic radiation generated by the active zone. This can be particularly useful if the electromagnetic radiation is to leave the optoelectronic semiconductor chip via the contacting layer.

In one embodiment of the optoelectronic semiconductor chip, the first contact structure is ring-shaped. An emission surface of the optoelectronic semiconductor chip is arranged inside the ring-shaped first contact structure. The second contact structure is flat. The flat second contact structure can be arranged on the substrate.

In one embodiment of the optoelectronic semiconductor chip, the first contact structure is flat. The second contact structure is ring-shaped. An emission surface of the optoelectronic semiconductor chip is arranged inside the ring-shaped second contact structure. In this case, it can be provided that the first contact structure is reflective for electromagnetic radiation from the optoelectronic semiconductor chip and the electromagnetic radiation leaves the optoelectronic semiconductor chip through the emission surface after being reflected at the first contact structure.

In one embodiment of the optoelectronic semiconductor chip, the contacting layer comprises indium tin oxide. Indium tin oxide can be a mixed oxide, for example consisting of 90 percent indium(III) oxide (In2O3) and 10 percent tin(IV) oxide (SnO2). In one embodiment of the optoelectronic semiconductor chip, the contacting layer comprises the first material. In both cases, the active zone can be contacted via the contacting layer.

In one embodiment of the method, the photonic crystal is applied in such a way that the first material is first applied as a flat layer. The recesses are then created. The second material is then applied in such a way that the recesses are at least partially filled with the second material.

In one embodiment of the method, the second material is applied in a preferred direction. The active zone and the first material are at an angle to the preferred direction, for example at an angle of between 30 and 80 degrees to the preferred direction. The second material can be applied in particular by means of a sputtering process or by means of molecular beam epitaxy.

In one embodiment of the method, the second material is applied by means of spin coating and/or plasma deposition. This enables a simple process, especially if the recesses are to be completely filled with the second material.

In one embodiment of the method, the active zone and the first material are rotated during the application of the second material. This makes it possible to create the recesses with a cavity that are closed with the second material.

In one embodiment of the method, after the second material has been applied, the second material is removed until the first material is exposed again. This can be done, for example, by polishing and/or grinding.

In one embodiment of the method, the recesses are produced using an anisotropic etching process. The anisotropic etching process can be a dry etching process and in particular a plasma etching and/or an ion beam etching.

• 1 einen Querschnitt eines optoelektronischen Halbleiterchips;
• 2 einen weiteren Querschnitt des optoelektronischen Halbleiterchips der 1;
• 3 ein Ablaufdiagramm eines Verfahrens zur Herstellung eines optoelektronischen Halbleiterchips;
• 4 einen Querschnitt eines weiteren optoelektronischen Halbleiterchips;
• 5 Zwischenschritte der Herstellung eines optoelektronischen Halbleiterchips;
• 6 ein weiteres Ablaufdiagramm eines Verfahrens zur Herstellung eines optoelektronischen Halbleiterchips;
• 7 einen Querschnitt eines weiteren optoelektronischen Halbleiterchips;
• 8 einen Querschnitt eines weiteren optoelektronischen Halbleiterchips;
• 9 einen Zwischenschritt bei der Herstellung des optoelektronischen Halbleiterchips der 8;
• 10 einen Querschnitt eines weiteren optoelektronischen Halbleiterchips; und
• 11 einen Zwischenschritt bei der Herstellung des optoelektronischen Halbleiterchips der 10.

The above-described properties, features and advantages of this invention and the manner in which they are achieved will become clearer and more clearly understandable in connection with the following description of the embodiments, which are explained in more detail in connection with the drawings. In each case, in a schematic representation,

• 1 a cross-section of an optoelectronic semiconductor chip;
• 2 another cross-section of the optoelectronic semiconductor chip of the 1 ;
• 3 a flow chart of a method for producing an optoelectronic semiconductor chip;
• 4 a cross-section of another optoelectronic semiconductor chip;
• 5 Intermediate steps in the production of an optoelectronic semiconductor chip;
• 6 another flow chart of a method for producing an optoelectronic semiconductor chip;
• 7 a cross-section of another optoelectronic semiconductor chip;
• 8th a cross-section of another optoelectronic semiconductor chip;
• 9 an intermediate step in the production of the optoelectronic semiconductor chip of the 8th ;
• 10 a cross-section of another optoelectronic semiconductor chip; and
• 11 an intermediate step in the production of the optoelectronic semiconductor chip of the 10 .

1 shows a cross section of an optoelectronic semiconductor chip 100, having an active zone 110 with a pn junction 111 for generating electromagnetic radiation 101, a photonic crystal 120, a contacting layer 150 adjacent to the photonic crystal 120, a first contact structure 161 and a second contact structure 162. The photonic crystal 120 is arranged between the active zone 110 and the contacting layer 150. The first contact structure 161 is electrically conductively connected to a first side 112 of the active zone 111 via the contacting layer 150. The second contact structure 162 is electrically conductively connected to a second side 113 of the active zone 110. The photonic crystal 120 has a periodic structure 121 consisting of at least a first material 122 with a first refractive index and a second material 123 with a second refractive index. The first material 122 has periodically arranged recesses 124 which are at least partially filled with the second material 123. The first refractive index is greater than the second refractive index. In the embodiment of the optoelectronic semiconductor chip 100 of the 1 the recesses 124 are completely filled with the second material.

The first material 122 and/or the second material 123 can comprise a dielectric. It can be provided that the first material 122 and/or the contacting layer 150 comprise a doped semiconductor material. Both the first material 122 and the second material 123 can have a solid state of aggregation. The second material 123 can also be arranged exclusively in the recesses 124.

Because the photonic crystal 120 has the second material 123, which is at least partially arranged in the recesses 124 of the first material 122, the optoelectronic semiconductor chip 100 is easier to manufacture, since the second material 123 can close the recesses 124 and thus applying the contact layer 150 is easier. In particular, when applying the contact layer 150, it can be prevented that a material of the contact layer 150 gets into the recesses 124. The greater the difference between the first refractive index and the second refractive index, the better the photonic crystal 120 is suited for the optoelectronic semiconductor chip 100.

Such an optoelectronic semiconductor chip 100 can be designed as a PCSEL (photonic crystal surface-emitting laser). In particular, a single laser mode can then be excited and thus an emission power of this single laser mode can be maximized.

The photonic crystal has a first crystal side 125 which faces away from the active zone 110, i.e. borders on the contacting layer 150. A second crystal side 126 faces the active zone 110. Between the 1 In addition to the layers shown in the active zone 110, the photonic crystal 120, the contacting layer 150 and possibly also the contact structures 161, 162, further layers may be provided which are 1 are not shown. These additional layers may include, for example, cladding layers and/or electron blocking layers.

In 1 an optional substrate 102 is also shown. The substrate 102 is arranged between the active zone 110 and the second contact structure 162. The substrate is electrically conductive and can in particular consist of a doped semiconductor material.

In one embodiment of the optoelectronic semiconductor chip, the first material 122 comprises a III-V semiconductor material, for example based on gallium nitride (GaN). Other alloys, for example made from different elements of group III or group V of the periodic table of elements, can also be used.

In one embodiment of the optoelectronic semiconductor chip, the second material 123 comprises silicon dioxide (SiO2) and/or magnesium fluoride (MgF2) and/or calcium fluoride (CaF2). These materials have a low second refractive index compared to typical semiconductor materials that can be used as the first material. This results in an efficient photonic crystal 120. In particular, silicon dioxide and/or magnesium fluoride and/or calcium fluoride can be combined with gallium nitride as the first material 122 to form the photonic crystal 120.

In one embodiment of the optoelectronic semiconductor chip 100, the photonic crystal 120 adjoins the active zone 110. In particular, the photonic crystal 120 can be directly the active zone 110, as for example in 1 Alternatively, a conductive intermediate layer can be provided (not shown in 1 shown). A distance between the active zone 110 or the pn junction 111 and the photonic crystal 120 can be selected based on an emission wavelength of the optoelectronic semiconductor chip 100 and thus of the emitted electromagnetic radiation 102.

In one embodiment of the optoelectronic semiconductor chip 100, the active zone 110 has a first region 114 with a first doping and a second region 115 with a second doping. The first region 114 and the second region 115 form the pn junction. At least one quantum well, in particular a plurality of quantum wells, is arranged in the first region 114. This enables a simple construction of the optoelectronic semiconductor chip 100.

In one embodiment of the optoelectronic semiconductor chip 100, the first region 114 has at least one p-doped GaN quantum well, in particular a plurality of p-doped GaN quantum wells. In this case, the first material 122 can also have p-doped GaN. In one embodiment of the optoelectronic semiconductor chip 100, the second region 115 has an n-doped GaN substrate. The substrate 102 can then also be n-doped gallium nitride. The pn junction 111 of the active zone 110 is formed by the p-doped quantum well or the p-doped GaN quantum wells and the n-doped GaN substrate, wherein a wavelength of the optoelectronic semiconductor chip 100 can be set by the dimensions of the p-doped GaN quantum well or the p-doped GaN quantum wells.

In one embodiment of the optoelectronic semiconductor chip 100, the contacting layer 150 is transparent to electromagnetic radiation 101 generated by the active zone 110. This can be particularly useful if the electromagnetic radiation 101 is to leave the optoelectronic semiconductor chip 100 via the contacting layer 150, as in 1 shown. Transparent in this context can mean that at most 25 percent, preferably at most 10 percent and in particular at most 2 percent of the emitted electromagnetic radiation 101 is absorbed by the contacting layer 150.

In one embodiment of the optoelectronic semiconductor chip 100, the first contact structure 161 is ring-shaped. This can mean in particular that the first contact structure 161 is circumferential around the optoelectronic semiconductor chip 100. An emission surface 103 of the optoelectronic semiconductor chip 100 is arranged inside the ring-shaped first contact structure 161. The second contact structure 162 is flat.

In one embodiment of the optoelectronic semiconductor chip 100, the contacting layer 150 comprises an indium tin oxide. Indium tin oxide can be a mixed oxide, for example consisting of 90 percent indium(III) oxide (In2O3) and 10 percent tin(IV) oxide (SnO2). In one embodiment of the optoelectronic semiconductor chip 100, the contacting layer 150 comprises the first material 122. In both cases, the active zone 110 can be contacted via the contacting layer 150.

The optoelectronic semiconductor chip 100 can be soldered onto a carrier by means of the first contact structure 161 and/or the second contact structure 162. This enables the optoelectronic semiconductor chip 100 to be easily installed in a component or device. The contact structures 161, 162 can be metal layers and in particular can comprise copper and/or silver and/or gold.

2 shows a cross section of the optoelectronic semiconductor chip 100 of the 1 at the level of the photonic crystal. The recesses 124 are arranged in a rectangular pattern. Three by five recesses 124 are shown. Of course, the number of recesses 124 can be significantly larger. Furthermore, a different geometry of the recesses 124 can be provided, for example in a hexagonal arrangement.

3 shows a flow chart 200 of a method for producing an optoelectronic semiconductor chip 100, which corresponds to the optoelectronic semiconductor chip 100 of the 1 and 2 can correspond. In a first method step 210, it is provided that an active zone 110 with a pn junction 111 is provided. In a second method step 220, a photonic crystal 120 is applied to the active zone 110. The photonic crystal 120 has a periodic structure 121 consisting of at least a first material 122 with a first refractive index and a second material 123 with a second refractive index. The first material 122 has periodically arranged recesses 124 which are at least partially filled with the second material 123. The first refractive index is greater than the second refractive index. Then, in a third method step 230, a contacting layer 150 is applied to the photonic crystal 120 such that the photonic crystal 120 is arranged between the active zone 110 and the contacting layer 150. In a fourth method step 240, a first contact structure 161 is applied such that the first contact structure 161 is electrically conductively connected to a first side 112 of the active zone 110 via the contacting layer 150. In a fifth method step 250, a second contact structure 162 is applied such that the second contact structure 162 is electrically conductively connected to a second side 113 of the active zone 110. The fourth method step 240 and the fifth method step 250 can be carried out in any order and, if necessary, also simultaneously. It can be provided that the active zone 110 is provided on a substrate 102 in the first method step 210.

4 shows a cross section through another optoelectronic semiconductor chip 100, which corresponds to the optoelectronic semiconductor chip 100 of the 1 and 2 corresponds, unless differences are described below. The recesses 124 are closed on the first crystal side 125 by the second material 123. A closed surface made of first material 122 and second material 123 is therefore arranged on the first crystal side 125. This enables a defined structure of the photonic crystal 120 and easier attachment of the contacting layer 150. Furthermore, the recesses 124 on the second crystal side 126 have a cavity 127. The cavity 127 can be filled with a gas, in particular with air. The gas, in particular the air, can have a third refractive index close to 1, so that a difference between the first refractive index and the third refractive index is as large as possible, so that an efficient photonic crystal 120 can be provided. By combining this with the closure of the recesses 124 with the second material 123 on the first crystal side 125, it can be achieved in particular that the contacting layer 150 can be applied to the photonic crystal 120 without material of the contacting layer 150 being able to get into the recesses 124.

5 shows intermediate products during the production of the optoelectronic semiconductor chip 100. First, the optional substrate 102 with the active zone 110 with the pn junction 111 is provided. This corresponds to the status after the first method step 210. The first material 122 is then applied to the first side 112 of the active zone 110. The first material 122 is applied in particular as a flat layer. The first material 122 can then be structured in order to form the recesses 124, wherein the recesses 124 are guided to the first side 112 of the active zone. The recesses 124 can be produced, for example, using an anisotropic etching process. The anisotropic etching process can be a dry etching process and in particular a plasma etching and/or an ion beam etching.

Due to the anisotropic etching process, the recesses 124 can in particular be cylindrical or frustoconical, wherein in the case of frustoconical recesses 124 it can be provided that a diameter of the recess 124 on the first crystal side 125 is only slightly larger than a diameter of the recess 124 on the second crystal side 126. In particular it can be provided that a diameter of the recess 124 on the first crystal side 125 deviates from a diameter of the recess 124 on the second crystal side 126 by only a maximum of 10 percent, in particular by a maximum of 5 percent.

The second material 123 is then applied in such a way that the recesses 124 are at least partially, here completely, filled with the second material 123. The second material 123 is also arranged above the first material 122. The second material 123 is then removed again until the first material 122 is exposed again. This creates the photonic crystal 120. The contact layer 150 can then be applied and the contact structures. This results in the optoelectronic semiconductor chip 100 of the 1 and 2 .

6 shows a flow chart 200 of the method of 3 , in which the second method step 220 is divided into sub-steps that correspond to the 5 shown intermediate steps. In a first application step 221, the first material 122 is applied to the active zone 110. In a structuring step 222, the first material 122 is structured and the recesses 124 are formed in the process. In a second application step 223, the second material 123 is then applied. In a removal step 224, the second material 123 is removed again to such an extent that the first material 122 is exposed again. The first application step 221, the structuring step 222, the second application step 223 and the removal step 224 form the second method step 220.

It can be provided that the first material 122 is applied in the first application step 221 by means of a sputtering process or by means of molecular beam epitaxy. It can be provided that the second material 123 is applied in the second application step 223 by means of spin coating and/or by means of plasma deposition. This enables a simple process, in particular especially when the recesses 124 are to be completely filled with the second material.

7 shows a cross section through another optoelectronic semiconductor chip 100, which corresponds to the optoelectronic semiconductor chip 100 of the 1 and 2 corresponds, unless differences are described below. The recesses 124 are completely filled with the second material 123, but can also be filled analogously to 4 Cavities 127 are provided. The first contact structure 161 is arranged flat on the contacting layer 150. The second contact structure 162 is arranged in a ring shape on the substrate 102. An emission surface 103 of the optoelectronic semiconductor chip 100 is arranged inside the ring-shaped second contact structure 162. In this case, it can be provided that the first contact structure 161 is reflective for electromagnetic radiation 101 of the optoelectronic semiconductor chip 100 and the electromagnetic radiation 101 leaves the optoelectronic semiconductor chip 100 through the emission surface 103 after being reflected at the first contact structure 161. In this embodiment, it can also be provided that the substrate 102 is transparent for the electromagnetic radiation 101 emitted by the active zone 110. Transparent in this context can mean that at most 25 percent, preferably at most 10 percent and in particular at most 2 percent of the emitted electromagnetic radiation 101 is absorbed by the substrate. The contacting layer 150 can also be transparent to the electromagnetic radiation 101 emitted by the active zone 110. Transparent in this context can mean that at most 25 percent, preferably at most 10 percent and in particular at most 2 percent of the emitted electromagnetic radiation 101 is absorbed by the contacting layer 150.

8th shows a cross section of another optoelectronic semiconductor chip 100, which corresponds to the semiconductor chip 100 of the 4 corresponds, unless differences are described below. In this embodiment, too, the recesses 124 on the first crystal side 125 are closed by the second material 123. Furthermore, the recesses 124 on the second crystal side 126 also have a cavity 127. The cavity 127 can be filled with a gas, in particular with air. In this embodiment, however, the second material 123 is in contrast to the 4 not the same thickness everywhere, but arranged obliquely within the recesses 124. Such an optoelectronic semiconductor chip 100 is easy to manufacture.

9 shows a cross section through an intermediate product during the second application step 223 in the production of the optoelectronic semiconductor chip 100 of the 8th The second material 123 is applied from a material source 170 in a preferred direction 128. The structured first material 122 and the active zone 110 are at an angle to the preferred direction 128, for example at an angle between 30 and 80 degrees to the preferred direction 128. In particular, a recess direction 129 is arranged at an angle between 30 and 80 degrees to the preferred direction 128, wherein the recess direction 129 can correspond to a direction of the anisotropic etching process. As a result, a part of the recesses 124 is covered by the first material 122, so that the oblique arrangement of the second material 123 is created in the recesses 124. The second material 123 can be applied in particular by means of a sputtering process or by means of molecular beam epitaxy and the material source 170 can be designed accordingly.

10 shows a cross section of another optoelectronic semiconductor chip 100, which corresponds to the semiconductor chip 100 of the 8th unless differences are described below. The recesses 124 are rotationally symmetrical. Also in 10 An enlargement of a region of the second material 123 in one of the recesses 124 is shown, whereby the second material can also be arranged in this way in several or all of the recesses 124. The second material 123 has a cylindrical basic structure 131. If the recesses 124 are not cylindrical but frustoconical, the second material 123 can have a frustoconical basic structure instead. The second material 123 has a conical recess 132 facing the cavity 127.

10 shows a cross section through an intermediate product during the second application step 223 in the production of the optoelectronic semiconductor chip 100 of the 10 The second material 123 is applied from a material source 170 in a preferred direction 128. The structured first material 122 and the active zone 110 are at an angle to the preferred direction 128, for example at an angle between 30 and 80 degrees to the preferred direction 128. In particular, a recess direction 129 is arranged at an angle between 30 and 80 degrees to the preferred direction 128, wherein the recess direction 129 can correspond to a direction of the anisotropic etching process. The active zone 110 and the first material 122 are rotated during the application of the second material 123. As a result, a part of the recesses 124 is covered by the first material 122, so that the arrangement of the second material 123 with the cylindrical base structure 131 and the conical recess 132 in the recesses 124. The second material 123 can be applied in particular by means of a sputtering process or by means of molecular beam epitaxy and the material source 170 can be designed accordingly.

In the embodiments of the optoelectronic semiconductor chips 100 of the 4 , 8th and 10 can be analogous to 7 It can also be provided that the first contact structure 161 is flat and the second contact structure 162 is ring-shaped, in which case the electromagnetic radiation 101 can also be reflected at the first contact structure 161 and both the material of the contacting layer 150 and the material of the substrate 102 are transparent to the electromagnetic radiation 101.

The invention has been illustrated and described in more detail using the preferred embodiments. However, the invention is not limited to the disclosed examples. Rather, other variations can be derived by the person skilled in the art from the described embodiments without departing from the scope of the invention.

LIST OF REFERENCE SYMBOLS

100

optoelectronic semiconductor chip

101

electromagnetic radiation

102

Substrat

103

Emission area

110

active zone

111

pn junction

112

first page

113

second page

114

first area

115

second area

120

photonic crystal

121

periodic structure

122

first material

123

second material

124

Recess

125

first crystal page

126

second crystal side

127

cavity

128

Preferred direction

129

Recess direction

131

Basic structure

132

conical recess

150

Contact layer

161

first contact structure

162

second contact structure

170

Material source

200

Flowchart

210

first procedural step

220

second process step

221

first application step

222

Structuring step

223

second application step

224

Removal step

230

third procedural step

240

fourth procedural step

250

fifth procedural step

Claims (20)

Optoelectronic semiconductor chip (100), comprising an active zone (110) with a pn junction (111) for generating electromagnetic radiation (101), a photonic crystal (120), a contacting layer (150) adjacent to the photonic crystal (120), a first contact structure (161) and a second contact structure (162), wherein the photonic crystal (120) is arranged between the active zone (110) and the contacting layer (150), wherein the first contact structure (161) is electrically conductively connected to a first side (112) of the active zone (110) via the contacting layer (150), wherein the second contact structure (162) is electrically conductively connected to a second side (112) of the active zone (110), wherein the photonic crystal (120) has a periodic structure (121) consisting of at least a first material (122) with a first refractive index and a second Material (123) having a second refractive index, wherein the first material (122) has periodically arranged recesses (124) which are at least partially filled with the second material (123), wherein the first refractive index is greater than the second refractive index. Optoelectronic semiconductor chip (100) according to Claim 1 , wherein the recesses (124) are closed by the second material (123) on a first crystal side (125) facing away from the active zone (110). Optoelectronic semiconductor chip (100) according to Claim 2 , wherein the recesses (124) on a second crystal side (126) facing the active zone (110) has a cavity (127). Optoelectronic semiconductor chip (100) according to Claim 3 , wherein the cavity (127) is filled with a gas. Optoelectronic semiconductor chip (100) according to Claim 3 or 4 , wherein the recess (124) is rotationally symmetrical, wherein the second material (123) has a cylindrical or frustoconical basic structure (131), wherein the second material (123) has a conical recess (132) facing the cavity. Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 5 , wherein the first material (122) comprises GaN. Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 6 wherein the second material (123) comprises SiO2 and/or MgF2 and/or CaF2. Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 7 , wherein the photonic crystal (120) is adjacent to the active zone (110). Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 8th , wherein the active zone (110) has a first region (114) with a first doping and a second region (115) with a second doping, wherein the first region (114) and the second region (115) form the pn junction (111), wherein at least one quantum well is arranged in the first region (114). Optoelectronic semiconductor chip (100) according to Claim 9 , wherein the first region (114) comprises at least one p-doped GaN quantum well and the second region (115) comprises an n-doped GaN substrate. Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 10 , wherein the contacting layer (150) is transparent to electromagnetic radiation (101) generated by the active zone (110). Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 11 , wherein the first contact structure (161) is annular and an emission surface (103) of the optoelectronic semiconductor chip (100) is arranged in the interior of the annular first contact structure (161), wherein the second contact structure (162) is flat. Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 11 , wherein the first contact structure (161) is planar, wherein the second contact structure (162) is annular and an emission surface (103) of the optoelectronic semiconductor chip (100) is arranged in the interior of the annular second contact structure (162). Optoelectronic semiconductor chip (100) according to one of the Claims 1 until 13 , wherein the contacting layer (150) comprises an indium tin oxide and/or the first material (122). Method for producing an optoelectronic semiconductor chip with the steps: - providing an active zone (110) with a pn junction (111); - applying a photonic crystal (120) to the active zone (110), the photonic crystal (120) having a periodic structure (121) consisting of at least a first material (122) with a first refractive index and a second material (123) with a second refractive index, the first material (122) having periodically arranged recesses (124) which are at least partially filled with the second material (123), the first refractive index being greater than the second refractive index; - applying a contacting layer (150) to the photonic crystal (120) such that the photonic crystal (120) is arranged between the active zone (110) and the contacting layer (150); - Applying a first contact structure (161) such that the first contact structure (161) is electrically conductively connected to a first side (112) of the active zone (110) via the contacting layer (150); - Applying a second contact structure (162) such that the second contact structure (162) is electrically conductively connected to a second side (112) of the active zone (110). Procedure according to Claim 15 , wherein the photonic crystal (120) is applied in such a way that first the first material (122) is applied as a flat layer, then the recesses (124) are created and then the second material (123) is applied in such a way that the recesses (124) are at least partially filled with the second material (123). Procedure according to Claim 16 , wherein the second material (123) is applied in a preferred direction (128), wherein the active zone (110) and the first material (122) are oblique to the preferred direction. Procedure according to Claim 16 or 17 , wherein the active zone (110) and the first material (122) are rotated during the application of the second material (123). Procedure according to one of the Claims 16 until 18 , wherein after the application of the second material (123), the second material (123) is removed again until the first material (122) is exposed again. Procedure according to one of the Claims 16 until 19 , wherein the recesses (124) are produced using an anisotropic etching process.

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