OPTOELECTRONIC COMPONENT AND METHOD FOR PRODUCING THE SAME

Abstract

An optoelectronic component (10) is specified, comprising a semiconductor body (6) with an active region (4) suitable for emission of radiation and comprising a quantum well structure, wherein the quantum well structure comprises at least one quantum well layer (41) and barrier layers (42), a first electrical contact (1) and a second electrical contact (2), wherein the active region (4) comprises at least one intermixed region (44) and at least one non-intermixed region (43).

The at least one quantum well layer (41) and the barrier layers (42) are at least partially intermixed in the intermixed region (44), such that the intermixed region (44) comprises a larger electronic bandgap than the at least one quantum well layer (41) in the non-intermixed region (43). The first electrical contact (1) is a metal contact arranged on a radiation exit surface of the semiconductor body (6), wherein the intermixed region (44) is arranged below the first contact (1) in the vertical direction. Further, a method for producing the optoelectronic component (10) is specified.

Claims

1. An optoelectronic component, comprising a semiconductor body with an active layer suitable for emitting radiation and comprising a quantum well structure, wherein the quantum well structure comprises at least a quantum well layer and barrier layers. a first electrical contact and a second electrical contact, wherein the active region comprises at least one intermixed region and at least one non-intermixed region the at least one quantum well layer and the barrier layers in the intermixed region are at least partially intermixed, so that the intermixed region comprises a larger electronic bandgap than the at least one quantum well layer in the non-intermixed region, the first electrical contact is a metal contact arranged on a radiation exit surface of said semiconductor body, and the intermixed region is arranged below the first contact (1) in the vertical direction, and the intermixed region comprises a width of less than 10 μm.

2. The optoelectronic component according to claim 1, wherein the first contact comprises a width of less than 10 μm.

3. The optoelectronic component according to claim 1, wherein the electronic bandgap in the intermixed region is larger by at least 0.05 eV than in the non-intermixed region.

4. The optoelectronic component according to claim 1, wherein the first contact is an n-contact and the second contact is a p-contact of the semiconductor body.

5. The optoelectronic component according to claim 1, wherein the second contact is arranged on a main surface of the semiconductor body opposite the radiation exit surface.

6. The optoelectronic component according to claim 1, wherein the semiconductor body is based on an arsenide compound semiconductor material, a phosphide compound semiconductor material or a nitride compound semiconductor material.

7. The optoelectronic component according to claim 1, wherein the intermixed region and the non-intermixed region comprise the same dopant concentration.

8. The optoelectronic component according to claim 1, wherein the optoelectronic component is an LED.

9. A method for producing an optoelectronic component, comprising: producing a semiconductor body with an active layer suitable for emitting radiation and comprising a quantum well structure, wherein the quantum well structure comprises at least one quantum well layer and barrier layers, applying a dielectric layer to a contact region of the semiconductor body, wherein the dielectric layer comprises a coefficient of thermal expansion different from that of the semiconductor body, perform a thermal treatment wherein atoms diffuse from the semiconductor body into the dielectric layer and create vacancies in the semiconductor body, wherein a diffusion of the vacancies in the semiconductor body creates a intermixed region in the active layer and wherein the at least one quantum well layer and the barrier layers are at least partially intermixed in the intermixed region such that the intermixed region comprises a larger electronic bandgap than the at least one quantum well layer in the non-intermixed region and the intermixed region comprises a width of less than 10 μm, removing the dielectric layer from the contact region of the semiconductor body, and applying a metal layer to the contact region of the semiconductor body to form a first electrical contact in the contact region.

10. The method according to claim 9, wherein the dielectric layer is a SiO.sub.2 layer.

11. The method according to claim 9, wherein the semiconductor body comprises a Ga-containing semiconductor material, and wherein Ga atoms diffuse from the semiconductor body into the dielectric layer during the temperature treatment.

12. The method according to claim 9, wherein the temperature treatment is performed at a temperature of at least 700° C.

13. The method according to claim 9, wherein, next to the dielectric layer, a further dielectric layer is applied to the semiconductor body, which comprises a larger coefficient of thermal expansion than the semiconductor body.

14. The method according to claim 13, wherein the further dielectric layer is a SrF.sub.2 layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention is explained in more detail below by means of exemplary embodiments in connection with FIGS. 1 and 2.

[0031] In the Figures:

[0032] FIG. 1A shows a schematic illustration of a cross-section through an example of the optoelectronic component,

[0033] FIG. 1B shows a schematic detail view of the active layer in the non-intermixed region in the example of the optoelectronic component,

[0034] FIG. 1C shows a schematic illustration of the course of the electronic bandgap of the active layer in the lateral direction in the example of the optoelectronic component, and

[0035] FIGS. 2A to 2D show a schematic illustration of an example of the method for producing the optoelectronic component.

DETAILED DESCRIPTION

[0036] Components that are the same or have the same effect are each provided with the same reference signs in the figures. The components shown and the proportions of the components to one another are not to be regarded as true to scale.

[0037] FIG. 1A illustrates an example of the optoelectronic component 10. The optoelectronic component 10 may in particular be an LED. The optoelectronic component 10 comprises a semiconductor body 6 which comprises a p-type semiconductor region 3, an n-type semiconductor region 5 and an active layer 4 arranged between the p-type semiconductor region 3 and the n-type semiconductor region 5. In particular, the active layer 4 is a radiation-emitting active layer 4. The p-type semiconductor region 3 and the n-type semiconductor region 5 may each include one or more semiconductor layers. The p-type semiconductor region 3 includes one or more p-doped semiconductor layers, and the n-doped semiconductor region 5 includes one or more n-doped semiconductor layers. It is also possible that the p-type semiconductor region 3 and/or the n-type semiconductor region 5 include one or more undoped semiconductor layers.

[0038] The semiconductor body 6 of the optoelectronic component 10 is preferably based on a III-V compound semiconductor material, in particular on an arsenide, phosphide or nitride compound semiconductor material. In this case, the material is selected based on the desired emission wavelength of the optoelectronic component 10.

[0039] For example, with a nitride compound semiconductor material, radiation in the UV, blue, and green spectral ranges can be generated. With a phosphide compound semiconductor material, for example, radiation in the green to red spectral range can be generated. For example, with an arsenide compound semiconductor material, radiation in the red to infrared spectral range can be generated.

[0040] For example, the semiconductor body 6 may include In.sub.xAl.sub.yGa.sub.1-x-yAs, In.sub.xAl.sub.yGa.sub.1-x-yP or In.sub.xAl.sub.yGa.sub.1-x-yN, each with 0≤x≤1, 0≤y≤1, and x+y≤1. In this regard, the III-V compound semiconductor material need not necessarily comprise a mathematically exact composition according to any of the above formulas. Rather, it may comprise one or more dopants as well as additional constituents. For simplicity, however, the above formulas include only the essential constituents of the crystal lattice, even though these may be partially replaced by small amounts of additional substances.

[0041] The active layer 4 of the optoelectronic component 10 is a quantum well structure comprising a non-intermixed region 43 and an intermixed region 44. A detailed view of the active layer 4 in the non-intermixed region 43 is shown in FIG. 1B. The active layer 4 comprises alternating quantum well layers 41 and barrier layers 42. The barrier layers 42 comprise a larger electronic band gap than the quantum well layers 41.

[0042] The quantum well layers 41 and barrier layers 42 of the active layer 4 are at least partially intermixed in an intermixed region 44 in the optoelectronic component 10 shown in FIG. 1A. In the intermixed region 44, in particular, the semiconductor material of the quantum well layers 41 is at least partially intermixed with the semiconductor material of the barrier layers 42, which comprises the larger electronic band gap. As a result, the active layer 4 in the intermixed region 44 comprises a larger electronic band gap than the quantum well layers 41 in the non-intermixed region 43.

[0043] The optoelectronic component 10 comprises a first electrical contact 1 and a second electrical contact 2 for electrical contacting. For example, the first electrical contact is the p-contact and the second electrical contact 2 is the re-contact of the optoelectronic component 10. The first electrical contact 1 is a metal contact arranged at a radiation exit surface 9 of the optoelectronic component 10. The first electrical contact 1 and/or the second electrical contact 2 may in particular each comprise a metal such as, for example, gold, silver, aluminum, titanium or platinum, or an alloy or a layer sequence of these metals.

[0044] In the optoelectronic component 10, the intermixed region 44 of the active layer 4 is arranged below the first electrical contact 1. Preferably, the intermixed region 44 comprises substantially the same width as the first electrical contact 1. In particular, the intermixed region 44 is arranged centered below the first electrical contact 1. In the perpendicular direction, the intermixed region 44 is not directly adjacent to the first electrical contact 1, but is spaced apart from the first electrical contact 1 by, for example, one or more semiconductor layers of the n-type semiconductor region 5.

[0045] The arrangement of the intermixed region 44 below the first electrical contact 1 has the advantage that the electronic band gap is increased in this region. The course of the electronic band gap in the lateral direction in the example of the optoelectronic component 10 is schematically illustrated in FIG. 1C. In the region below the first electrical contact 1, the distance between the conduction band edge E.sub.L and the valence band edge E.sub.B, and thus the electronic band gap, is increased compared to the neighboring non-intermixed regions of the quantum well structure. Preferably, the electronic band gap in the intermixed region below the first electrical contact is larger than in the non-intermixed region by at least 0.05 eV, for example between 0.05 eV and 0.3 eV and preferably between 0.08 eV and 0.1 eV. The increased electronic band gap in the intermixed region can be detected, for example, by measuring the photoluminescence in this region.

[0046] As can be seen in FIG. 1A, the enlarged electronic band gap in the intermixed region 44 causes electrons e moving from the first electrical contact 1 to the active zone 4 and holes h moving from the second electrical contact 2 toward the active zone 4 to substantially not recombine with each other in the intermixed region 44. Instead, the electrons e and the holes h diffuse, as outlined by arrows in FIG. 1A, into the adjacent non-intermixed regions 43 and recombine only there with the emission of radiation.

[0047] In order to diffuse as many electrons and holes as possible into the non-intermixed regions 43, it is advantageous if the width of the intermixed region 44 is smaller than the diffusion length of the charge carriers e, h in the semiconductor body. Therefore, the semiconductor body 6 is advantageously based on a material system with large carrier diffusion length such as GaAs, InAlGaAs, InGaAlP or InP. However, the intermixed region 44 can also be implemented in nitride semiconductor materials such as InGaN, GaN or AlGaN.

[0048] Preferably, the width of the intermixed region 44 and/or the first contact 1 is less than 10 μm and more preferably less than 2 μm. For example, the width of the intermixed region and/or the first contact is between 100 nm and 10 μm, preferably between 1 μm and 2 μm.

[0049] The reduced recombination of charge carriers in the region below the first electrical contact 1 has the advantage that less radiation is generated below the first electrical contact 1 which could be absorbed at the first electrical contact 1. Rather, the recombination of charge carriers and thus the emission of radiation occurs more in the non-intermixed regions 43 above which no electrical contact is arranged and thus the radiation exit surface 9 is exposed. Light extraction from the optoelectronic component 10 is improved in this way.

[0050] In the following FIGS. 2A to 2D, a method for producing the optoelectronic component 10 by means of intermediate steps is illustrated by way of example.

[0051] In the intermediate step shown in FIG. 2, a semiconductor body 6 has been produced which comprises the p-type semiconductor region 3, the active layer 4 formed as a quantum well structure, and the n-type sub region 5. The active layer 4 comprises alternating quantum well layers and barrier layers as described above in connection with FIG. 1B.

[0052] A dielectric layer 7, which comprises a coefficient of thermal expansion different from that of the semiconductor body 6, has been applied to a contact region of the semiconductor body 6, the contact region being a region of the surface of the semiconductor body 6 to which the first electrical contact is to be applied in a subsequent method step. The dielectric layer 7 is, for example, a SiO.sub.2 layer. The coefficient of thermal expansion of SiO.sub.2 is lower than the coefficient of thermal expansion of III-V semiconductor materials such as arsenide, phosphide or nitride compound semiconductor materials. For example, the coefficient of thermal expansion of SiO.sub.2 is about 0.5*10.sup.−6/K and the coefficient of thermal expansion of GaAs is about 6*10.sup.−6/K. Thus, the thermal expansion of the semiconductor material is much larger than the thermal expansion of the dielectric layer 7.

[0053] On the regions of the surface of the semiconductor body 6, which are arranged adjacent to the dielectric layer 7, a further dielectric layer 8 can be applied, which comprises a larger coefficient of thermal expansion than the dielectric layer and the semiconductor body. The further dielectric layer 8 is, for example, a SrF.sub.2 layer. It is possible that the further dielectric layer 8 is also applied to an opposite surface of the semiconductor body 6.

[0054] In a further step, which is schematically illustrated in FIG. 2B, a temperature treatment of the semiconductor body 6 is performed. The temperature treatment may be carried out in the temperature range of about 700° C. to 1200° C., for example, at a temperature of about 900° C. The temperature treatment lasts, for example, from 10 s to 10 min, preferably from about 1 min to 2 min. Due to the different coefficients of thermal expansion of the semiconductor body 6 and the dielectric layer 7, a stress is generated between the materials of the dielectric layer 7 and the semiconductor body 6 in the region of the dielectric layer 7.

[0055] In particular, in the case of a dielectric layer made of SiO.sub.2, a large compressive stress is created in the semiconductor body due to the thermal treatment. The thermally induced strain causes atoms 11 to move from the semiconductor body 6 into the dielectric layer 7. For example, gallium atoms 11 may diffuse from the semiconductor material of the semiconductor body 6 into the dielectric layer 7 during the thermal treatment. The atoms 11 diffused from the semiconductor body 6 leave vacancies that diffuse in the semiconductor body 6. By the diffusion of the vacancies the quantum well layers and barrier layers are at least partially intermixed in the region below the dielectric layer 7, creating the intermixed region 44 in the active layer 4.

[0056] In the regions of the semiconductor body 6 arranged laterally from the dielectric layer 7, in which a SrF.sub.2 layer is arranged as a further dielectric layer 8, the thermal stress is substantially lower due to the larger coefficient of thermal expansion of the further dielectric layer 8 and therefore causes substantially no diffusion of atoms of the semiconductor body 6 into the further dielectric layer 8. Outside the region of the dielectric layer 7, therefore, substantially no vacancy diffusion takes place, so that the active layer 4 is not intermixed there. After the temperature treatment, therefore, outside the contact region of the semiconductor body 6 to which the dielectric layer 7 is applied, there are regions 43 of the active layer 4 which are not intermixed.

[0057] In the example described here, the production of the intermixed region 44 in the active layer 4 is advantageously carried out by a thermally induced diffusion process in which no foreign atoms are introduced into the intermixed region 44. The doping of the semiconductor body 6 is therefore not deliberately changed during the production of the intermixed region 44. In particular, the non-intermixed regions 43 and the intermixed region 44 of the active layer 4 nominally comprise the same or no doping.

[0058] In a further intermediate step of the method, which is schematically illustrated in FIG. 2C, the dielectric layer 7 and the further dielectric layer 8 have been removed again from the semiconductor body 6. This can be done, for example, with an etching process suitable for this purpose.

[0059] In a next step of the method, which is illustrated in FIG. 2D, the first electrical contact 1 and the second electrical contact 2 have been applied to the semiconductor body 6. The first electrical contact 1 is applied to the contact region of the semiconductor body 6 on which the dielectric layer 7 was previously arranged. In this way, it is achieved that the intermixed region 44 is arranged below the first electrical contact 1.

[0060] Preferably, the first electrical contact 1 is applied in such a way that the shape and/or width of the first electrical contact 1 substantially correspond to the shape and/or width of the intermixed region 44. Particularly preferably, the first electrical contact 1 and the intermixed region 44 are congruent when viewed from above the semiconductor body 6. The first electrical contact 1 is, for example, the n-contact of the optoelectronic component.

[0061] The second electrical contact 2 is applied to a surface of the semiconductor body 6 opposite to the first electrical contact 2. The second electrical contact 2 may, for example, be applied over the entire surface of the main surface of the semiconductor body opposite the radiation exit surface 9. The second electrical contact 2 may, for example, be designed as a mirror contact comprising a material reflective of the radiation emitted by the active layer 4, such as silver or aluminum. It is possible that the second electrical contact 2 is arranged between the semiconductor body 6 and a carrier (not illustrated) of the semiconductor body 6. The second electrical contact 2 is, for example, the p-contact of the optoelectronic component 10.

[0062] The invention is not limited by the description based on the exemplary embodiments. Rather, the invention encompasses any new feature as well as any combination of features, which in particular includes any combination of features in the patent claims, even if that feature or combination itself is not explicitly specified in the claims or exemplary embodiments.