Optoelectronic semiconductor component with high al-content alinp layer

Abstract

The invention relates to an optoelectronic semiconductor component (10) comprising a first semiconductor layer (110) of the n-type with composition Alx1Gay1In1-x1-y1P, where 0<x1<1, 0≤y1<1, an active zone (115) and a second semiconductor layer (120) of the p-type with composition Alx2Gay2In1-x2-y2P, where 0.51<x2<1, 0≤y2<0.1. The semiconductor layers (110, 120) and the active zone (115) form a semiconductor layer stack (125) and are arranged above a substrate (100).

Description

[0001] OPTOELECTRONIC SEMICONDUCTOR COMPONENT WITH HIGH-Al CONTENT AlInP LAYER DESCRIPTION A light-emitting diode (LED) is a light-emitting device based on semiconductor materials. Typically, an LED comprises differently doped semiconductor layers and an active zone. When electrons and holes recombine with each other in the region of the active zone, for example, because a corresponding voltage is applied, electromagnetic radiation is generated. The present invention is based on the object of providing an improved optoelectronic semiconductor component. According to embodiments, the object is achieved by the subject matter of the independent patent claims. Further developments are defined in the dependent patent claims. An optoelectronic semiconductor component has a first semiconductor layer of the composition Al x1 Ga y1 In 1-x1-y1P of n-type, with 0 <x1<1, 0≤y1<1, eine aktive Zone und eine zweite Halbleiterschicht der Zusammensetzung Al x2 Ga y2 In 1-x2-y2P of p-type, with 0.51 <x2<1, 0≤y2<0,1 auf. Die Halbleiterschichten bil- den einen Halbleiterschichtstapel aus und sind über einem Sub- strat angeordnet. Beispielsweise kann y2 kleiner als 0,05 sein. Beispielsweise kann x2 größer als 0,55 sein. Gemäß Ausführungsformen enthält die aktive Zone GaP-haltige Halbleiterschichten. Das optoelektronische Halbleiterbauelement kann weiterhin eine Übergitterstruktur zwischen der zweiten Halbleiterschicht vom p-Typ und der aktiven Zone enthalten, wobei die Übergit- terstruktur abwechselnd tensil und kompressiv verspannte Schichten aufweist. Beispielsweise kann die Übergitterstruktur an die zweite Halb- leiterschicht vom p-Typ angrenzen. Gemäß Ausführungsformen ist die zweite Halbleiterschicht vom p-Typ als Übergitterstruktur ausgebildet, wobei die Übergit- terstruktur abwechselnd tensil und kompressiv verspannte Schichten aufweist. Beispielsweise haben die tensil verspannten Schichten eine Zu- sammensetzung Al x In 1-xP, with x > 0.51. According to embodiments, the compressively strained layers have a composition (AlGa) y In 1-yP with y < 0.51. For example, in the compressively strained layers, a ratio of Al to Ga is greater than 30%. According to embodiments, a distance of the second p-type semiconductor layer to the substrate is greater than the distance of the first n-type semiconductor layer to the substrate. The accompanying drawings serve to understand embodiments of the invention. The drawings illustrate embodiments and, together with the description, serve to explain the same. Further embodiments and many of the intended advantages will become apparent from the following detailed description. The elements and structures shown in the drawings are not necessarily drawn to scale. Like reference numerals refer to like or corresponding elements and structures. Fig. 1 shows a schematic cross-sectional view of an optoelectronic semiconductor component according to embodiments. Fig.2A shows a cross-sectional view of an optoelectronic semiconductor device according to further embodiments. FIG. 2B shows an enlarged section of the cross-sectional view shown in FIG. 2A. FIG. 3A shows a schematic cross-sectional view of an optoelectronic semiconductor device according to further embodiments. FIG. 3B shows an enlarged view of a section of the cross-sectional view shown in FIG. 3A. In the following detailed description, reference is made to the accompanying drawings, which form a part of the disclosure and in which specific embodiments are shown for illustrative purposes. In this context, directional terminology such as "top", "bottom", "front", "back", "over", "on", "in front of", "behind", "front", "rear", etc., refers to the orientation of the figures just described.Since the components of the embodiments can be positioned in different orientations, the directional terminology is for illustrative purposes only and is not limiting in any way. The description of the embodiments is not limiting, since other embodiments exist and structural or logical changes can be made without departing from the scope defined by the patent claims. In particular, elements of embodiments described below can be combined with elements of other described embodiments, unless the context indicates otherwise. Semiconductor materials described within the scope of the present disclosure include, in particular, phosphide semiconductor compounds, by means of which, for example, green or longer wavelength light can be generated, such as, for example, GaAsP, AlGaInP, GaP, AlGaP.The stoichiometric ratio of the compound semiconductor materials can vary. These semiconductor materials are typically grown epitaxially over a suitable growth substrate, for example, a GaAs substrate. The terms "lateral" and "horizontal," as used in this description, are intended to describe an orientation or alignment that is substantially parallel to a first surface of a substrate or semiconductor body. This can be, for example, the surface of a wafer or a chip (die). The horizontal direction can, for example, lie in a plane perpendicular to a growth direction during layer growth. The term "vertical," as used in this description, is intended to describe an orientation that is substantially perpendicular to the first surface of a substrate or semiconductor body.The vertical direction may, for example, correspond to a growth direction during the growth of layers. The term "semiconductor layer" may encompass a plurality of sub-semiconductor layers, each with different compositions. Fig. 1 shows a schematic cross-sectional view of an optoelectronic semiconductor component according to embodiments. An optoelectronic semiconductor component 10 has a first semiconductor layer 110 of the composition Al. x1 Ga y1 In 1-x1-y1 P of n-type. Where 0 <x1<1,0≤y1<1. Das optoelektronische Halbleiterbauelement 10 weist ferner eine aktive Zone 115 zur Strahlungserzeugung und eine zweite Halbleiterschicht 120 der Zusammensetzung Al x2 Ga y2 In 1-x2-y2P of p-type. 0.51 <x2<1 und 0≤y2<0,1 oder kleiner als 0,05. Die erste Halb- leiterschicht 110, die aktive Zone 115 und die zweite Halb- leiterschicht 120 bilden einen Halbleiterschichtstapel 125 aus. Die aktive Zone 115 ist zwischen der ersten und der zwei- ten Halbleiterschicht 110, 120 angeordnet. Der Halbleiter- schichtstapel 125 ist über einem geeigneten Substrat 100 ange- ordnet. Das Substrat 100 kann beispielsweise ein GaAs-Substrat sein, das für das epitaktische Wachstum von Halbleiterschichten der Zusammensetzung Al x2 In 1-x2 P is particularly suitable. In particular, using a suitable substrate material, it is possible to form the first semiconductor layer 110 of the n-type composition Al x1 Ga y1 In 1-x1-y1P with good crystal quality and a low dislocation density. For example, the lattice constant of the material of the substrate 100 can be similar to the lattice constant of the first n-type semiconductor layer 110. The first semiconductor layer 110 can be formed adjacent to the substrate 100. According to further embodiments, suitable intermediate layers, for example buffer layers, can be arranged between the substrate 100 and the first semiconductor layer 110. The active zone 115 can, for example, have a pn junction, a double heterostructure, a single quantum well structure (SQW), or a multiple quantum well structure (MQW) for generating radiation. The term "quantum well structure" has no significance with regard to the dimensionality of the quantization. It thus includes, among other things, quantum wells, quantum wires, and quantum dots, as well as any combination of these layers.The active zone 115 can contain GaP-containing semiconductor layers. The term “GaP-containing semiconductor layer” refers to a compound semiconductor layer that contains Ga and P as composition elements. For example, the GaP-containing semiconductor layer can additionally contain As. Specific examples include AlGaInP, AlGaInAsP, AlGaP, InGaAsP, and others, each with different stoichiometric ratios. For example, the active zone 115 can have quantum well structures made of AlGaInP material. These can, for example, contain alternating layers, each with a different Al:Ga ratio. The second semiconductor layer 120 of the composition Al. x2 Ga y2 In 1- x2-y2P-type P can be doped with C, Mg, or Zn, for example. A layer thickness of the second semiconductor layer 120 can, for example, be in a range from 20 to 600 nm. The Al content can be ≥0.51, for example >0.55 or 0.57. For example, an upper limit of the Al content of the second semiconductor layer 120 can be less than 0.7 (70%). The Ga content can be very low, for example, less than 0.05 (5%). Furthermore, it is possible for the second semiconductor layer 120 to contain no Ga. Due to the comparatively high Al content, a band gap of the second semiconductor layer is comparatively large. As a result, the second semiconductor layer 120 acts as an electron barrier. More precisely, a confinement or inclusion of the electrons in the active zone 115 takes place in this way.If a voltage is applied to the optoelectronic semiconductor component 10 to generate radiation, electrons within the active zone can migrate to a lesser extent into the p-doped region due to the presence of the second semiconductor layer 120. As a result, the leakage current is reduced, thereby increasing the light output of the LED. Even at higher temperatures, it is more difficult for electrons to overcome the barrier formed by the second semiconductor layer 120. Overall, better light output, improved brightness, and more stable temperature behavior with regard to the light output and brightness of the optoelectronic semiconductor component 10 can thus be achieved. An upper limit for the Al content can be approximately 70%. At a higher Al / In ratio, the lattice constant of the second semiconductor layer differs greatly from that of the underlying layers.As a result, high stresses and dislocations may occur, which may lead to strain and the formation of dislocations in the active zone 115. This may impair the performance of the LED. According to embodiments, one or more further layers may be arranged between the active zone 115 and the second p-type semiconductor layer. The optoelectronic semiconductor component 10 may further comprise a second contact element 106, for example a contact layer that is electrically connected to the second semiconductor layer 120. The second contact element 106 may, for example, comprise a suitable conductive material, for example a metal or a transparent conductive oxide. The second contact element 106 may be arranged directly adjacent to the second semiconductor layer 120.According to further embodiments, further suitable layers can be arranged between the second semiconductor layer 120 and the second contact element 106. Furthermore, the optoelectronic semiconductor component 10 can have a first contact element 105, for example a contact layer that is electrically connected to the first semiconductor layer 110. For example, with a corresponding conductivity of the substrate 100, the first contact element 105 can be arranged on a side of the substrate facing away from the first semiconductor layer 110. According to further embodiments, however, a part of the semiconductor layer stack can also be etched back in a suitable manner, so that the first contact element 105 can directly adjoin the first semiconductor layer 110. Fig. 2A shows a schematic cross-sectional view of the optoelectronic semiconductor component 10 according to further embodiments. Fig.2B shows an enlarged view of the second semiconductor layer 120. In addition to elements that have been described with reference to FIG. 1, the optoelectronic semiconductor component 10 further comprises a superlattice structure 133. As illustrated in FIGS. 2A and 2B, this superlattice structure 133 is arranged between the second semiconductor layer 120 and the active zone 115. The superlattice structure 133 comprises alternating tensile strained layers 135 and compressively strained layers 136. For example, the total number of layers 135, 136 may be in a range from 10 to 100. Each of the individual layers may, for example, have a layer thickness of less than 30 nm. A minimum layer thickness may, for example, be 5 nm. A total thickness of the superlattice structure 133 may, for example, be greater than 50 nm. The total thickness of the superlattice structure 133 can be less than 2000 nm.The tensile stressed layers 135 can, for example, each have a composition of Al. x In y P, where x is greater than 0.51. For example, x can be greater than 0.55 or greater than 0.57. A value of exactly 0.51 would indicate a lattice match. The compressively strained layers 136 have a composition of (AlGa) y In 1-yP with y < 0.51. For example, y can be less than 0.49 or less than or equal to 0.47. For example, the ratio of Al to Ga in these layers can vary in a range from 30% to 100% Al. The composition ratio within the tensile or compressively strained layers 135, 136 can change within the superlattice. For example, the Al content in the tensile and / or compressively strained layers 135, 136 can increase with increasing distance from the active zone 115. Due to the presence of the superlattice structure 133, strains and crystal defects that arise in the second semiconductor layer 120 due to the high Al content can be prevented from propagating into the active zone 115. Thus, the superlattice 133 can serve as a defect barrier. Fig. 3A shows a cross-sectional view of an optoelectronic semiconductor component 10 according to further embodiments.3B shows the exact structure of the second semiconductor layer 120. As illustrated in FIG. 3B, according to embodiments, the entire second semiconductor layer 120 with increased Al content is realized as a superlattice structure 133. More precisely, the second semiconductor layer 120 with increased Al content consists of alternately arranged, tensile-strained layers 135 and compressively strained layers 136. For example, the individual layers can be doped with Mg. The structure of the individual layers can be as discussed with reference to FIGS. 2A and 2B. For example, it is possible for the tensile-strained layers 135 to not contain Ga. The compressively strained layers 136 can each contain Ga. The tensile-strained layers 135 can each have a high Al content.Because the second p-type semiconductor layer 120 is implemented as a superlattice structure 133, the tensile strain of the individual tensile strained layers 135 can be compensated by the compressively strained layers 136. As a result, a greater layer thickness of the second p-type semiconductor layer 120 with an increased Al content and thus a wider barrier is possible. For example, the layer thickness of the second p-type semiconductor layer 120 can be greater than 50 nm. According to embodiments, the layer thickness of the second semiconductor layer 120 can be less than 1200 nm. The described optoelectronic semiconductor components 10 can be used, for example, in automotive applications or in the horticulture sector.Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that the specific embodiments shown and described may be replaced by a variety of alternative and / or equivalent configurations without departing from the scope of the invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, the invention is limited only by the claims and their equivalents. LIST OF REFERENCE SYMBOLS 10 Optoelectronic semiconductor component 100 Substrate 105 First contact element 106 Second contact element 110 First semiconductor layer 115 Active zone 120 Second semiconductor layer 125 Semiconductor layer stack 133 Superlattice structure 135 Tensile strain layer 136 Compressive strain layer.

Claims

CLAIMS 1. Optoelectronic semiconductor component (10) comprising: a first semiconductor layer (110) of the n-type of the composition Al x1 Ga y1 In 1-x1-y1 P, with 0 <x1<1, 0≤y1<1, einer aktiven Zone (115) und einer zweiten Halbleiterschicht (120) vom p-Typ der Zu- sammensetzung Al x2 Ga y2 In 1-x2-y2P, with 0.51 <x2<1, 0≤y2<0,1, die einen Halbleiterschichtstapel (125) ausbilden und über einem Substrat (100) angeordnet sind, wobei die zweite Halbleiterschicht (120) vom p-Typ aus einer Übergitterstruktur (133) besteht, und die Übergit- terstruktur (133) abwechselnd tensil und kompressiv verspannte Schichten (135, 136) aufweist.

2. Optoelektronisches Halbleiterbauelement (10) nach An- spruch 1, wobei x2 größer als 0,55 ist.

3. Optoelektronisches Halbleiterbauelement (10) nach An- spruch 1 oder 2, wobei die aktive Zone (115) GaP-haltige Halb- leiterschichten enthält.

4. Optoelektronisches Halbleiterbauelement (10) nach einem der vorhergehenden Ansprüche, wobei die tensil verspannten Schichten (135) eine Zusammensetzung Al x In 1-x P, with x > 0.

51.

5. Optoelectronic semiconductor component (10) according to one of the preceding claims, wherein the compressively strained layers (136) have a composition (AlGa) y In 1-y P have with y < 6. The optoelectronic semiconductor component (10) according to claim 5, wherein in the compressively strained layers (136) a ratio of Al to Ga is greater than 30%.

7. The optoelectronic semiconductor component (10) comprising: a first n-type semiconductor layer (110) of composition Al x1 Ga y1 In 1-x1-y1 P, with 0 <x1<1, 0≤y1<1, einer aktiven Zone (115) und einer zweiten Halbleiterschicht (120) vom p-Typ der Zu- sammensetzung Al x2 Ga y2 In 1-x2-y2P, with 0.51 <x2<1, 0≤y2<0,1, die einen Halbleiterschichtstapel (125) ausbilden und über einem Substrat (100) angeordnet sind, ferner mit einer Übergitterstruktur (133) zwischen der zweiten Halbleiter- schicht (120) vom p-Typ und der aktiven Zone (115), wobei die Übergitterstruktur (133) abwechselnd tensil und kompressiv verspannte Schichten (135, 136) aufweist.

8. Optoelektronisches Halbleiterbauelement (10) nach An- spruch 7, wobei die Übergitterstruktur (133) direkt an die zweite Halbleiterschicht (120) vom p-Typ angrenzt.

9. Optoelektronisches Halbleiterbauelement (10) nach An- spruch 7 oder 8, wobei die tensil verspannten Schichten (135) eine Zusammensetzung Al x In 1-x P, with x > 0.

51.

10. Optoelectronic semiconductor component (10) according to one of claims 7 to 9, wherein the compressively strained layers (136) have a composition (AlGa) y In 1-yP with y < 0.

51.

11. Optoelectronic semiconductor component (10) according to claim 10, wherein in the compressively strained layers (136) a ratio of Al to Ga is greater than 30%.

12. Optoelectronic semiconductor component (10) according to one of the preceding claims, wherein a distance of the second p-type semiconductor layer (120) from the substrate (100) is greater than the distance of the first n-type semiconductor layer (110) from the substrate (100).

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