Optoelectronic Semiconductor Component

Abstract

In an embodiment, an optoelectronic semiconductor component includes a semiconductor layer sequence with a doped first layer, a doped second layer, an active zone configured to generate radiation by electroluminescence between the first layer and the second layer, and a side surface extending transversely to the active zone and delimiting the semiconductor layer sequence in a lateral direction, two electrodes for electrical contact between the first and second layers and a cover layer located on the side surface in a region of the first layer, wherein the cover layer is in direct contact with the first layer, wherein a material of the cover layer alone and its direct contact with the first layer are configured to cause a formation of a depletion zone in the first layer, wherein the depletion zone comprises a lower concentration of majority charge carriers compared to a rest of the first layer, wherein the cover layer comprises a metal or a metal compound, and wherein the cover layer forms a Schottky contact with the first layer.

Claims

1.-16. (canceled)

17. An optoelectronic semiconductor component comprising: a semiconductor layer sequence with a doped first layer, a doped second layer, an active zone configured to generate radiation by electroluminescence between the first layer and the second layer, and a side surface extending transversely to the active zone and delimiting the semiconductor layer sequence in a lateral direction; two electrodes for electrical contact between the first and second layers; and a cover layer located on the side surface in a region of the first layer, wherein the cover layer is in direct contact with the first layer, wherein a material of the cover layer alone and its direct contact with the first layer are configured to cause a formation of a depletion zone in the first layer, wherein the depletion zone comprises a lower concentration of majority charge carriers in comparison with a rest of the first layer, wherein the cover layer comprises a metal or a metal compound, and wherein the cover layer forms a Schottky contact with the first layer.

18. The optoelectronic semiconductor component according to claim 17, wherein the first layer is n-doped and the second layer is p-doped, and wherein a work function for electrons in the cover layer is greater than a work function for electrons in the first layer.

19. The optoelectronic semiconductor component according to claim 17, wherein the cover layer is electrically conductive.

20. The optoelectronic semiconductor component according to claim 17, wherein the cover layer is located on the side surface at a level of the active zone, and wherein the depletion zone extends up to the active zone.

21. The optoelectronic semiconductor component according to claim 17, further comprising: a doped, third layer which comprises the same type of doping as the first layer, wherein a doping concentration in the first layer is lower than a doping concentration in the third layer, and wherein the first layer is arranged between the active zone and the third layer.

22. The optoelectronic semiconductor component according to claim 17, wherein the second layer comprises a lower effective doping at the side surface than in a rest of the second layer.

23. The optoelectronic semiconductor component according to claim 17, wherein the cover layer is located in the region of the second layer on the side surface, and wherein a contact resistance of at least 100Ω is present between the second layer and the cover layer.

24. The optoelectronic semiconductor component according to claim 17, wherein the cover layer is electrically insulated from all electrodes of the optoelectronic semiconductor component.

25. The optoelectronic semiconductor component according to claim 17, wherein at least one recess is located in the semiconductor layer sequence, the recess extending through the active zone and being delimited by the side surface in the lateral direction, and wherein the cover layer located in a region of the recess on the side surface.

26. The optoelectronic semiconductor component according to claim 25, further comprising: a plurality of individually and independently drivable pixels, wherein each pixel is associated with a section of the semiconductor layer sequence, wherein each section is surrounded and delimited in the lateral direction by one or more side surfaces, wherein the sections of the semiconductor layer sequence are separated by recesses and are spaced apart from one another, and wherein the cover layer is located around each section of the semiconductor layer sequence at the side surfaces.

27. The optoelectronic semiconductor component according to claim 25, wherein the recess is filled with an electrically conductive material, and wherein the first layer or the second layer is electrically connected to one of the electrodes via the electrically conductive material.

28. An optoelectronic semiconductor component comprising: a semiconductor layer sequence with a doped first layer, a doped second layer, an active zone configured to generate radiation by electroluminescence between the first layer and the second layer, and a side surface extending transversely to the active zone and delimiting the semiconductor layer sequence in a lateral direction; two electrodes for electrical contact between the first and second layers; and a cover layer on the side surface in a region of the first layer, wherein the cover layer is in direct contact with the first layer, wherein a material of the cover layer alone and its direct contact with the first layer are configured to cause a formation of a depletion zone in the first layer, wherein the depletion zone comprises a lower concentration of majority charge carriers compared to a rest of the first layer, wherein the first layer is n-doped and the second layer is p-doped, and wherein a work function for electrons in the cover layer is greater than a work function for electrons in the first layer.

29. The optoelectronic semiconductor component according to claim 28, wherein the cover layer is electrically insulated from all electrodes of the optoelectronic semiconductor component.

30. The optoelectronic semiconductor component according to claim 28, wherein the cover layer is formed of a doped semiconductor.

31. An optoelectronic semiconductor component comprising: a semiconductor layer sequence with a doped first layer, a doped second layer, an active zone configured to generate radiation by electroluminescence between the first layer and the second layer, and a side surface extending transversely to the active zone and delimiting the semiconductor layer sequence in a lateral direction; two electrodes for electrical contact between the first and second layers; and a cover layer on the side surface in a region of the first layer, wherein the cover layer is in direct contact with the first layer, wherein a material of the cover layer alone and its direct contact with the first layer are configured to cause a formation of a depletion zone in the first layer, wherein the depletion zone comprises a lower concentration of majority charge carriers compared to a rest of the first layer, and wherein the second layer comprises a lower effective doping at the side surface than in a rest of the second layer.

32. The optoelectronic semiconductor component according to claim 31, wherein the cover layer is formed of a doped semiconductor.

33. The optoelectronic semiconductor component according to claim 32, wherein a bandgap in the cover layer is larger than a bandgap in the first layer.

34. The optoelectronic semiconductor component according to claim 31, wherein a bandgap in the cover layer is larger than a bandgap in the first layer.

35. The optoelectronic semiconductor component according to claim 30, wherein the cover layer is electrically insulated from all electrodes of the optoelectronic semiconductor component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Further advantageous embodiments and further designs of the optoelectronic semiconductor component result from the exemplary embodiments described below in connection with the figures. Elements that are identical, of the same kind or have the same effect are provided with the same reference signs in the figures. The figures and the proportions of the elements shown in the figures are not to be regarded as to scale. Rather, individual elements, in particular layer thicknesses, may be shown exaggeratedly large for better illustration and/or understanding.

[0063] FIGS. 1, 2 and 4-20 show various exemplary embodiments of the optoelectronic semiconductor component in cross-sectional views and plan views; and

[0064] FIGS. 3 and 4 show schematic band structures.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0065] FIG. 1 shows a first exemplary embodiment of an optoelectronic semiconductor component 1. A section of the semiconductor component 1 is shown here. The semiconductor component 1 is, for example, a thin-film semiconductor chip. The semiconductor component 1 comprises a semiconductor layer sequence 2 with a first layer 20, a second layer 21, and an active zone 22 between the first layer 20 and the second layer 21. The semiconductor layer sequence 2 is based, for example, on a III-V compound semiconductor material, such as AlInGaN.

[0066] The first layer 20 of the semiconductor layer sequence 2 is n-doped, for example, and the second layer 21 is correspondingly p-doped. But a reverse doping would also be conceivable. The active zone 22 is, for example, a pn junction.

[0067] The semiconductor component 1 further comprises electrodes 30, 31 for electrical contact of the semiconductor layer sequence 2. A first electrode 30 (n-electrode) is applied directly to the first layer 20 and is electrically conductively connected with the first layer 20. A second electrode 31 (p-electrode) is directly applied to the second layer 21 and is electrically conductively connected with the second layer 21. The electrodes 30, 31 comprise or consist, for example, of metal or a transparent conductive oxide, TCO for short.

[0068] A cover layer 4 is applied to a side surface 25 of the semiconductor layer sequence 2, which in the present case is an outer surface and laterally delimits the semiconductor layer sequence 2 and which extends transversely or perpendicularly to the active zone 22. The cover layer 4 is applied directly to the first layer 20, the active zone 22 and the second layer 21 at the side surface 25.

[0069] The cover layer 4 is formed of a material selected such that a depletion zone 24 is formed in the first layer 20 at the side surface 25 solely by the cover layer 4 and the direct contact with the first layer 20. In the depletion zone 24, the concentration of the majority charge carriers, in this case electrons, is lower than in the rest of the first layer 20.

[0070] FIG. 2 shows a second exemplary embodiment of the semiconductor component 1. In contrast to the semiconductor component of FIG. 1, here the cover layer 4 is selected in such a way that solely through the cover layer 4 and the direct contact to the second layer 21, a depletion zone 24 is also formed in the second layer 21 at the side surface 25. The depletion zone 24 in the second layer 21 has a lower concentration of majority charge carriers, in this case holes, than the rest of the second layer 21.

[0071] In FIG. 3, the band structures for the first layer 20, the cover layer 4, and the second layer 21 are shown in a diagram. For example, the band structures for the exemplary embodiment of FIG. 2 are shown. In the present case, the cover layer 4 is a layer made of a metal, for example Pt, Pd, Ti, Ni or NiAu.

[0072] The cover layer 4 comprises a work function q.Math.φm for electrons, which is higher than an electron affinity q.Math.χ in the first layer 20. Due to the direct contact of the cover layer 4 and the first layer 20, the Fermi energies Ef in the first layer 20 and the cover layer 4 equalize and a Schottky contact is formed. Both the conduction band El and the valence band Ev of the first layer 20 are bent. As a result, a potential barrier is formed for the electrons in the n-doped first layer 20, which blocks the electrons from entering the cover layer 4. Due to the bending of the conduction band El, the electrons in the first layer 20 are forced from the side surface 25 into the interior of the first layer 20. Thus, a depletion zone 24 is formed at the side surface 25 in the first layer 20.

[0073] It can also be seen that the direct contact of the cover layer 4 with the second layer 21 in the region of the side surface 25 creates a depletion zone 24 within the second layer 21, in which the concentration of holes is reduced compared to the rest of the second layer 21. This is again due to a curvature of the conduction band El and the valence band Ev of the second layer 21 at the side surface 25.

[0074] The depletion zones 24 in the layers 20, 21 at the side surface 25 suppress current flow along the side surface 25 and increase the efficiency of the semiconductor component 1.

[0075] In FIG. 4, the band structures in the first layer 20 and the cover layer 4 are shown for the case where the cover layer 4 is formed of a semiconductor material. For example, the material of the cover layer 4 is p-doped silicon oxide, such as alpha-SiO.sub.x:B. The band gap in the cover layer 4 is larger than in the first layer 20.

[0076] FIG. 5 shows an exemplary embodiment of the semiconductor component 1 in which the active zone 22 comprises, for example, a multi-quantum well structure.

[0077] FIG. 6 shows an exemplary embodiment of the semiconductor component 1, in which the semiconductor component 1 comprises, in addition to the first layer 20, a third 23 and a fourth 26 layer, both of which are also n-doped. The first layer 20 is arranged between the third layer 23 and the active zone 22. In the first layer 20, the doping concentration is lower than in the third layer 23. The cover layer 4 is in direct contact with the first layer 20 at the side surface 25 but not with the third 23 and fourth 26 layers.

[0078] In the exemplary embodiment of FIG. 6, advantageously, the dopant concentration of the first layer 20 is lower than in other n-doped regions. As a result, the width of the depletion zone 24 is increased.

[0079] FIG. 7 shows another exemplary embodiment of the optoelectronic semiconductor component 1. Here, the second layer 21 comprises a lower effective doping at the side surface 25 than in the rest of the second layer 21. For example, the second layer is doped with magnesium and the effective doping is reduced at the side surface 25 due to a diffusion of hydrogen (deactivated acceptors). In this way, a contact resistance to the cover layer 4 is increased, which is further beneficial for reducing current flow along the side surface 25.

[0080] FIG. 8 shows an exemplary embodiment of the semiconductor component 1 in which the cover layer 4 is drawn from the side surface 25 to the second electrode 31. In this case, the cover layer 4 is electrically insulated from the second electrode 31 by a dielectric layer 7. The dielectric layer 7 is formed, for example, of silicon oxide or silicon nitride.

[0081] In FIGS. 9 and 10, the exemplary embodiment of the optoelectronic semiconductor component 1 of FIG. 1 is shown, but this time not only as a detail, but in the overall view. FIG. 9 is a cross-sectional view and FIG. 10 is a plan view. It can be seen that the cover layer 4 covers all side surfaces 25 of the semiconductor layer sequence 2. The cover layer 4 extends in lateral direction all around the semiconductor layer sequence 2 and is formed coherently and without interruptions. As a result, a depletion zone 24 is formed on all side surfaces 25 in the region of the first layer 20, which completely surrounds a central region of the first layer 20 laterally.

[0082] FIG. 11 shows a further exemplary embodiment of an optoelectronic semiconductor component 1. In particular, this is a semiconductor chip in which, for example, the growth substrate for the semiconductor layer sequence 2 is removed, the semiconductor layer sequence 2 is arranged between the first electrode 30 and the second electrode 31.

[0083] FIG. 12 shows still another exemplary embodiment of the semiconductor component 1 in the form of a semiconductor chip. Here, the third layer 23 widens in the direction away from the active zone 22.

[0084] FIGS. 13 and 14 show an exemplary embodiment of a semiconductor component 1, in which the semiconductor component 1 is a pixelated semiconductor chip. FIG. 13 is a cross-sectional view and FIG. 14 is a plan view. The semiconductor layer sequence 2 is segmented into several island-shaped sections by recesses 5 in the form of trenches which together form a rectangular grid. Each of these sections is uniquely associated with a pixel 6 of the semiconductor component 1. Furthermore, each pixel 6 is uniquely assigned its own first electrode 30 and its own second electrode 31 for contacting the section of the semiconductor layer sequence 2. The pixels 6 can thus be electrically driven individually and independently of one another and emit electromagnetic radiation individually and independently of one another during operation. However, instead of individual first electrodes 30 or second electrodes 31 for each pixel 6, all pixels 6 may share a common first electrode 30 or a common second electrode 31.

[0085] It can be seen that the recesses 5 are delimited in the lateral direction by side surfaces 25 of the sections of the semiconductor layer sequence 2. A cover layer 4 is applied to each of these side surfaces 25 in the region of the recesses 5. As a result, depletion zones 24 are formed in each section of the semiconductor layer sequence 2 in the region of the first layer 20 at the side surfaces 25.

[0086] FIGS. 15 and 16 essentially show the exemplary embodiment of FIGS. 13 and 14. In FIGS. 13 and 14, each pixel 6 is uniquely assigned its own cover layer 4. The cover layer 4 of different pixels 6 are separated and spaced apart from each other. In FIGS. 15 and 16, on the other hand, the cover layers 4 of all pixels 6 are contiguous. In other words, a single, contiguous cover layer 4 is used here, covering all side surfaces 25 of all pixels 6.

[0087] FIGS. 17 (cross-sectional view) and 18 (plan view) show another exemplary embodiment of the semiconductor component 1, in which recesses 5 are again introduced into the semiconductor layer sequence 2. Here, however, the recesses 5 are not trenches but holes in the semiconductor layer sequence 2, each recess 5 being completely surrounded by the semiconductor layer sequence 2 in the lateral direction. In this case, although the recesses 5 penetrate the active zone 22 as in the preceding exemplary embodiments, the active zone 22 is still formed contiguously and is not segmented as in FIGS. 13 to 16.

[0088] Furthermore, the semiconductor component 1 of FIGS. 17 and 18 comprises only a second electrode 31, which is formed contiguously, and is breached by the recesses 5 in regions. The cover layer 4 is again applied to the side surfaces 25 of the semiconductor layer sequence 2 in the recesses 5, where it provides for the formation of the depletion zones 24.

[0089] FIGS. 19 and 20 show an exemplary embodiment of the semiconductor component 1 in which the electrodes 30, 31 are arranged on the same side of the semiconductor layer sequence 2. Here, recesses 5 in the form of holes penetrate the second layer 21 and the active zone 22 and open into the third layer 23. Within the recesses 5, the cover layer 4 is again applied to the side surfaces 25 of the semiconductor layer sequence 2 and provides for the formation of the depletion zones 24. A dielectric layer is applied to the sides of the cover layer 4 facing away from the side surfaces 25. The recesses 5 are further filled with an electrically conductive material 50, for example a metal. The dielectric layers within the recesses 5 provide electrical insulation between the electrically conductive material 50 and the cover layers 4. In the region of bottom surfaces of the recesses 5, the electrically conductive material 50 is in direct contact with the third layer 23. The filled recesses 5 thus form vias for electrical contact of the semiconductor layer sequence 2.

[0090] The invention is not limited to the exemplary embodiments by the description thereof. 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 these features or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.