RADIATION-EMITTING SEMICONDUCTOR COMPONENT AND METHOD FOR PRODUCING A RADIATION-EMITTING SEMICONDUCTOR COMPONENT

Abstract

The invention relates to a radiation-emitting semiconductor component comprising a semiconductor body which has an active zone for generating radiation and a radiation exit surface, a contact element which is arranged on the radiation exit surface at a first lateral distance from a first edge piece of the radiation exit surface and at a second lateral distance from a second edge piece of the radiation exit surface, and a decoupling structure for improving the decoupling of the radiation generated by the active zone, which decoupling structure is arranged on the radiation exit surface and has structural elements, wherein the structural elements vary in such a way that the radiation decoupling increases from the contact element to the first and/or second edge piece. Furthermore, a method is specified for producing a such a radiation-emitting semiconductor element.

Claims

1. A radiation-emitting semiconductor component comprising a semiconductor body comprising a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type, and an active zone which is intended for emission of radiation and is disposed between the first and second semiconductor regions, and a radiation exit face, a contact element which is disposed at a first lateral distance from a first edge piece of the radiation exit face and at a second lateral distance from a second edge piece of the radiation exit face, on said face, and a decoupling structure for improving the decoupling of the radiation emitted from the active zone, where the decoupling structure is a structured layer which is disposed at or on the radiation exit face and comprises a radiation-transmissive material, and has structural elements, wherein the structural elements vary in such a way that the radiative decoupling increases starting from the contact element up to the first and/or second edge piece.

2. The radiation-emitting semiconductor component as claimed in claim 1, wherein the structural elements vary in their size and/or shape and/or their reciprocal distance.

3. The radiation-emitting semiconductor component as claimed in claim 1, wherein size and/or reciprocal distance of the structural elements increase starting from the contact element up to the first and/or second edge piece.

4. The radiation-emitting semiconductor component as claimed in claim 1, comprising a cover element, where the cover element is disposed on an edge side of the radiation exit face.

5. The radiation-emitting semiconductor component as claimed in claim 4, wherein the cover element is of frame-like design.

6. The radiation-emitting semiconductor component as claimed in claim 1, wherein the contact element is disposed in central position on the radiation exit face.

7. The radiation-emitting semiconductor component as claimed in claim 1, wherein the decoupling structure is designed symmetrically in respect of the contact element.

8. The radiation-emitting semiconductor component as claimed in claim 1, having a first lateral extent which is at least 10 μm and at most 50 μm.

9. The radiation-emitting semiconductor component as claimed in claim 1, being of rectangular design in plan view onto the radiation exit face and having a second lateral extent which is at least 1 mm and at most 5 mm.

10. The radiation-emitting semiconductor component as claimed in claim 9, wherein the contact element is of rectangular design and the decoupling structure is of at least largely axisymmetrical design in respect of the contact element.

11. The radiation-emitting semiconductor component as claimed in claim 1, being of circular or square design in plan view onto the radiation exit face and having a second lateral extent which is at least 10 μm and at most 50 μm.

12. The radiation-emitting semiconductor component as claimed in claim 11, wherein the contact element is of circular or square design and the decoupling structure is of at least largely rotationally symmetrical design in respect of the contact element.

13. The radiation-emitting semiconductor component as claimed in claim 1, wherein the semiconductor body comprises Al.sub.nGa.sub.mIn.sub.1-n-mAs.sub.yP.sub.1-y, where 0≤n≤1, 0≤m≤1, n+m≤1 and 0≤y≤1.

14. The radiation-emitting semiconductor component as claimed in claim 1, wherein the semiconductor body has a passivation formed on an edge side.

15. A method for producing a radiation-emitting semiconductor component as claimed in claim 1, comprising: providing a semiconductor body comprising a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type, and an active zone which is intended for emission of radiation and is disposed between the first and second semiconductor regions, and a radiation exit face, forming a contact element which is disposed at a first lateral distance from a first edge piece of the radiation exit face and at a second lateral distance from a second edge piece of the radiation exit face, on said face, and forming a decoupling structure at or on the radiation exit face for improving the decoupling of the radiation emitted from the active zone, where the decoupling structure is a structured layer which comprises a radiation-transmissive material, and comprises structural elements, where the structural elements are varied in such a way that the radiative decoupling increases starting from the contact element up to the first and/or second edge piece.

16. The method as claimed in claim 15, wherein the decoupling structure is formed by an application to the radiation exit face of a contact layer which comprises TCO and is structured in such a way that it has structural elements whose size and/or reciprocal distance increase from inside to outside.

17. The method as claimed in claim 15, wherein the decoupling structure is formed by an application to the radiation exit face of an insulating layer which comprises a dielectric material and is structured in such a way that it has structural elements whose size and/or reciprocal distance increase from inside to outside.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Further advantages, preferred embodiments and developments of the semiconductor component and also of the method are apparent from the exemplary embodiments elucidated below in connection with FIGS. 1 to 5.

[0045] In the figures:

[0046] FIG. 1 shows a schematic cross-sectional view of a radiation-emitting semiconductor component according to a first exemplary embodiment,

[0047] FIG. 2D shows a schematic cross-sectional view of a radiation-emitting semiconductor component according to a comparative example, FIG. 2A shows a diagram representing a radiation density profile to be achieved over a width of the radiation-emitting semiconductor component, FIG. 2B shows a diagram representing a profile of radiative recombination over the width of the radiation-emitting semiconductor component, FIG. 2C shows a diagram representing different variants of a decoupling efficiency to be achieved over the width of the radiation-emitting semiconductor component, and FIG. 2E shows a schematic plan view of the radiation-emitting semiconductor component represented in FIG. 2D, according to the comparative example,

[0048] FIG. 3 shows a diagram representing profiles of radiative recombination of different variants of radiation-emitting semiconductor components according to the comparative example,

[0049] FIGS. 4A and 4B show various steps of a method for producing—and FIG. 4B a schematic cross-sectional view of—a radiation-emitting semiconductor component according to a second exemplary embodiment,

[0050] FIGS. 5A and 5B show various steps of a method for producing—and FIG. 5B a schematic cross-sectional view of—a radiation-emitting semiconductor component according to a third exemplary embodiment.

DETAILED DESCRIPTION

[0051] In the exemplary embodiments and figures, elements which are the same, of the same kind or have the same effect may each be given the same reference symbols. The elements represented and their proportions among one another should not necessarily be regarded as being true to scale; instead, individual elements may be represented with exaggerated magnitude for the purpose of greater ease of representation and/or of better comprehension.

[0052] FIG. 1 represents a first exemplary embodiment of a radiation-emitting semiconductor component 1. The radiation-emitting semiconductor component 1 has a semiconductor body 2, which comprises a first semiconductor region 3 of a first conductivity type, a second semiconductor region 5 of a second conductivity type, and an active zone 4 for the emission of radiation, disposed between the first and second semiconductor regions 3, 5. The semiconductor component 1 is intended preferably for emission of radiation at the longwave edge of the visible spectrum, more preferably in the red to infrared spectral range. The wavelength here may be between 600 nm inclusive and 1500 nm inclusive.

[0053] In particular, the first semiconductor region 3 is an n-conducting or n-doped semiconductor region and the second semiconductor region 5 is a p-conducting or p-doped semiconductor region. It is, however, also possible for the reverse situation to apply, and for the first semiconductor region 3 to be a p-conducting or p-doped semiconductor region and the second semiconductor region 5 to be an n-conducting or n-doped semiconductor region. This is the case, for example, if the semiconductor body 2 is flipped twice in the course of production.

[0054] For the regions 3, 4, 5 of the semiconductor body 2, or for layers contained in the semiconductor body 2 or the regions 3, 4, 5, suitable materials are preferably III/V semiconductor materials, more preferably materials from the material system Al.sub.nGa.sub.mIn.sub.1-n-mAs.sub.yP.sub.1-y, where 0≤n≤1, 0≤m≤1, n+m≤1, and 0≤y≤1.

[0055] Furthermore, the semiconductor body 2 has a radiation exit face 2A which is disposed on a side of the first semiconductor region 3 that is facing away from the active zone 4. Preferably a large part of the radiation generated in operation departs the semiconductor body 2 via the radiation exit face 2A. More particularly the radiation-emitting semiconductor component 1 may be a surface emitter. The emission characteristics of a surface emitter, in the case of the semiconductor component 1 represented in FIG. 1, may be achieved inter alia by at least partial removal of a growth substrate used for producing the regions 3, 4, 5.

[0056] The radiation-emitting semiconductor component 1 further comprises a decoupling structure 7, which is disposed on the radiation exit face 2A and is part of the semiconductor body 2. In the case of the first exemplary embodiment, therefore, the decoupling structure 7 is formed of a semiconductor material.

[0057] The decoupling structure 7 has structural elements 7A which vary in such a way that the radiative decoupling increases starting from a contact element 6 up to a first and/or second edge piece 2C, 2D.

[0058] In particular, a first lateral extent d of the structural elements 7A, which is determined parallel to a first lateral direction L1, and hence also the magnitude thereof, increases from inside to outside. Furthermore, a reciprocal distance a3 of the structural elements 7A, which is determined parallel to a principal plane of extent, spanned by the first lateral direction L1 and by a second lateral direction L2 disposed perpendicular to it (cf. FIG. 2E), may also increase from inside to outside.

[0059] The structural elements 7A have a convex, at least approximately hemispherical architecture. The reciprocal distance a3 between the structural elements 7A preferably corresponds, close to the edge 2C, 2D, approximately to the wavelength of the radiation generated in the active zone 4.

[0060] The contact element 6 is disposed at a first lateral distance a1 from the first edge piece 2C of the radiation exit face 2A and at a second lateral distance a2 from the second edge piece 2D of the radiation exit face 2A, on said face, with the first and second distances a1, a2 being determined parallel to the first lateral direction L1. Advantageously the size and reciprocal distance a3 between the structural elements 7A increase starting from the contact element 6 up to the first and second edge pieces 2C, 2D. In other words, the structural elements 7A disposed in the vicinity of the contact element 6 are smaller than the structural elements 7A disposed on the edge pieces 2C, 2D. As a result it is possible to achieve an increase in the radiative decoupling starting from the contact element 6 up to the first and second edge pieces 2C, 2D. The radiative recombination decreasing toward the first and second edge pieces 2C, 2D may therefore be at least partly compensated by the decoupling structure 7.

[0061] The first and second lateral distances a1, a2 are preferably of equal magnitude. In particular the contact element 6 is disposed in central position on the radiation exit face 2A. For example, the radiation-emitting semiconductor component 1 may have a first lateral extent b which is at least 10 μm and at most 50 μm, so that the first and second lateral distances a1, a2 are each between at least 5 μm and at most 25 μm.

[0062] The first semiconductor region 3 can be contacted electrically by means of the contact element 6. The contact element 6 advantageously comprises or consists of a transparent conductive oxide. The transparent design of the contact element 6 has the advantage that radiation generated beneath the contact element 6 can also be decoupled from the semiconductor component 1.

[0063] The contact element 6 may be rectangular, for instance strip-shaped or square, or circular in design, with the geometry of the contact element 6 preferably corresponding to the geometry of the semiconductor component 1 or semiconductor body 2.

[0064] The decoupling structure 7 is of symmetrical design in respect of the contact element 6. For example, the contact element may be of strip-shaped design (cf. FIG. 2E), with the decoupling structure 7 being of at least largely axisymmetrical design in respect of the contact element 6. Moreover, the contact element 6 may be of circular or square design, with the decoupling structure 7 being of at least largely rotationally symmetrical design in respect of the contact element 6.

[0065] The semiconductor body 2 has a passivation 11 formed on the edge side. The passivation 11 advantageously produces a reduction in the nonradiative recombination at the edge.

[0066] The radiation-emitting semiconductor component 1 has a further contact element 8, which is disposed at a first lateral distance a1′ from a first edge piece 2C′ of a bottom face 2B of the semiconductor body 2, lying opposite the radiation exit face 2A, and at a second lateral distance a2′ from a second edge piece 2D′ of the bottom face 2B, on said face. In particular the further contact element 8 is disposed in central position on the bottom face 2B and is intended for the electrical contacting of the second semiconductor region 5.

[0067] The radiation-emitting semiconductor component 1 advantageously has emission behavior of “Top-Head” kind, meaning in particular that the decoupled radiation has a flat beam profile, with the intensity of the radiation remaining substantially the same over the radiation exit face 2A. A beam profile of this kind is represented for example in FIG. 2A.

[0068] The problem on which the invention is based, and the solution to the problem, are elucidated in more detail in connection with FIGS. 2A to 2E and FIG. 3.

[0069] FIG. 2D shows a comparative example of a radiation-emitting semiconductor component 1, which has a semiconductor body 2 having a radiation exit face 2A and a bottom face 2B, a contact element 6 disposed on the radiation exit face 2A, and a cover element 9 disposed on the radiation exit face 2A, for obtaining a clearly delimited luminous area, and a further contact element 8 disposed on the bottom face 2B. Additionally the radiation-emitting semiconductor component 1 has a reflection layer 10 disposed on the bottom face 2B. In contradistinction to the radiation-emitting semiconductor component 1 according to the first exemplary embodiment, the radiation-emitting semiconductor component 1 according to the comparative example does not have a decoupling structure.

[0070] As is apparent from FIG. 2E, the radiation-emitting semiconductor component 1 is of rectangular, more particularly strip-shaped, design in plan view onto the radiation exit face 2A, and has a second lateral extent c which is at least 1 mm and at most 5 mm. This second lateral extent c is determined parallel to the second lateral direction L2.

[0071] The cover element 9 is of frame-like design, with the radiation exit face 2A being covered by the cover element 9 all round at the edge. Suitable materials include reflective materials such as Ag, for instance. Absorbing materials, more particularly blackening materials, are also suitable for the cover element 9.

[0072] The contact element 6 has a geometry which is adapted to the geometry of the semiconductor component 1, likewise in strip form. The first lateral extent b1 of the contact element 6 is preferably between 1 μm and 8 μm, preferably between 1 μm and 2 μm.

[0073] As is apparent from the diagram of FIG. 2B, the radiative recombination R decreases continuously, more particularly linearly, with the distance a from the center of the semiconductor component 1. One reason for this is that the distances a1, a2 are each situated in the range of the diffusion lengths of the charge carriers. The nonradiative recombination also increases owing to surface defects at the edge 2C, 2D of the semiconductor body 2.

[0074] FIG. 2C represents different profiles I, II of advantageous decoupling efficiencies A, which enable compensation of the decreasing radiative recombination R, so that a “Top-Head”-kind distribution of the luminance Jv as represented in FIG. 2A can be achieved. In the ideal case the decoupling efficiency A represents an inverse function (curve I) of the radiative recombination R. Also sufficient in fact, however, is a function approximated to the ideal curve I, and equating to a parabola like the curve II, for example.

[0075] FIG. 3 illustrates the results of various simulations for investigating the radiative recombination R. Parameters changed here were firstly the first lateral extent b1 of the contact element 6 (KI, KIII: b1=2 μm; KII, KIV: b1=8 μm) and secondly the edge passivation (KI, KII: without passivation; KIII, KIV: with passivation).

[0076] In the diagram of FIG. 3, the radiative recombination R [E28 cm-3/s] is plotted against the first lateral distance a [μm] from the center of the semiconductor component 1. The semiconductor component 1 has a first lateral extent b of 10 μm. The x-axis section “0” corresponds to the center of the semiconductor component 1. The x-axis section “5 μm” corresponds to the second edge piece 2D of the semiconductor component 1.

[0077] The curve III with maximum radiative recombination R shows a sharp gradient at the edge. As a result of the edge passivation, however, it is already possible to reduce the nonradiative recombination, as is clear from the comparison with curves I, II. The decrease at the edge can be at least partly compensated by the decoupling structure 7 (cf. FIGS. 1, 4B, 5B).

[0078] FIGS. 4A and 4B represent various steps in a method for producing a radiation-emitting semiconductor component 1 according to a second exemplary embodiment. FIG. 4B shows a radiation-emitting semiconductor component 1 according to the second exemplary embodiment.

[0079] Provided first of all is a semiconductor body 2, which comprises a first semiconductor region 3 of a first conductivity type, a second semiconductor region 5 of a second conductivity type, and an active zone 4 which is intended for emission of radiation and is disposed between the first and second semiconductor regions 3, 5. The semiconductor body 2 further comprises a radiation exit face 2A.

[0080] Applied successively to the radiation exit face 2A are a contact layer 13 and an insulating layer 12. The contact layer 13 preferably comprises or consists of TCO. The insulating layer 12 comprises or consists of a dielectric material, such as SiO or SiN, for example. The materials of the contact and insulating layers 13, 12 are advantageously transmissive for the radiation generated in the active zone 4.

[0081] The insulating layer 12 is structured by means of photolithography to generate a decoupling structure 7 which is disposed at or on the radiation exit face 2A. During the photolithography, a mask 14 is used whose radiation transmissiveness varies in the pattern of the decoupling structure 7 that is to be generated.

[0082] It is possible first to expose, through the mask 14, a photosensitive layer which is disposed on the semiconductor body 2 (not represented). In the course of the exposure, a mask structure resulting from regions with higher and lower radiation transmissiveness is transferred into the photosensitive layer. By means of the photosensitive layer, the mask structure can be transferred further into the insulating layer 12.

[0083] In the case of the first exemplary embodiment represented in FIG. 1, the mask structure is transferred correspondingly into the semiconductor body 2.

[0084] After the structuring of the insulating layer 12, contact elements 6, 8 can be applied on the radiation exit face 2A and the opposite bottom face 2B. In particular the contact element 6 is applied directly to the contact layer 13 in an opening in the insulating layer 12.

[0085] The radiation-emitting semiconductor component 1 produced in this way has the advantages already stated above.

[0086] FIG. 5B shows a third exemplary embodiment of a radiation-emitting semiconductor component 1, and FIGS. 5A and 5B show various steps in a method for producing said component.

[0087] According to the third exemplary embodiment, an insulating layer is omitted, and the decoupling structure 7 is formed by the application to the radiation exit face 2A of a contact layer 13 which comprises TCO and is structured in such a way that it has structural elements 7A whose size or first lateral extent d and reciprocal distance a3 increase from inside to outside.

[0088] The radiation-emitting semiconductor component 1 produced in this way has the advantages already stated earlier on above.

[0089] According to advantageous configurations, the radiation-emitting semiconductor components 1 according to the first to third exemplary embodiments may have a reflection layer 10 disposed on the bottom face 2B corresponding to the comparative example represented in FIG. 2D. Additionally or alternatively, the radiation-emitting semiconductor components 1 according to the first to third exemplary embodiments may have a cover element 9 disposed on the radiation exit face 2A, corresponding to the comparative example represented in FIG. 2D. Furthermore, the radiation-emitting semiconductor components 1 according to the second and third exemplary embodiments may have an edge passivation 11 corresponding to the first exemplary embodiment represented in FIG. 1.

[0090] The invention is not restricted by the description in relation to the exemplary embodiments. The invention instead encompasses each new feature and also each combination of features, including in particular each combination of features in the claims, even if that feature or that combination is not itself explicitly specified in the claims or exemplary embodiments.