DE102010029916A1 - Light-emitting semiconductor structure e.g. LED, for semiconductor device for creating electromagnetic radiation in different polarization directions, has two clad layer structures arranged on active zone - Google Patents

Abstract

The invention relates to a light-emitting semiconductor structure (100) with a cladding layer structure (110a, 110b) and at least one active zone (112) which is arranged in the cladding layer structure (110a, 110b) and has at least one quantum structure (112a, 112b) for generating electromagnetic radiation. According to the invention, the at least one quantum structure (112a, 112b) is formed from different compound semiconductors.

Description

State of the art

The invention relates to a light-emitting semiconductor structure having a cladding layer structure and at least one active zone arranged in the cladding layer structure, which has at least one quantum structure for generating electromagnetic radiation.

The invention further relates to a semiconductor device having a layer structure of a plurality of light-emitting semiconductor structures.

It is an object of the present invention to improve a semiconductor light-emitting structure and a semiconductor device having a plurality of semiconductor light-emitting structures in such a way that a more flexible use and an increased utility are provided.

Disclosure of the invention

This object is achieved in the light-emitting semiconductor structure of the aforementioned type according to the invention that the at least one quantum structure of different compound semiconductors is formed, which are advantageously given further degrees of freedom with respect to the generation of electromagnetic radiation. According to the invention, it has been recognized that an active zone with such a configured quantum structure combines advantageous properties of different compound semiconductors with one another.

According to a preferred embodiment, in which the quantum structure is formed as quantum dot and / or as quantum wire and / or as quantum well, a first volume region of the quantum structure is formed of a first compound semiconductor material second volume region of the quantum structure is formed of a second compound semiconductor material.

As a quantum film, d. H. essentially planar, formed quantum structures of small layer thickness, for example, a first surface portion of the first compound semiconductor material may be formed, while a second surface portion of the second compound semiconductor material is formed. It is also possible, as it were, to realize the quantum film according to the invention as a "double layer", wherein the quantum film has a layer structure with a first layer of the first compound semiconductor material and a second layer of the second compound semiconductor material arranged thereon. Combinations of both variants are also possible, as well as the provision of a plurality of surface sections and / or layers.

It is also conceivable to combine more than two different compound semiconductors (eg GaAs, InAlGaAs, GaAsP, InGaAsP) in order to produce the quantum structure according to the invention.

The provision of two or more quantum structures to form an active zone is also possible, as well as the provision of multiple active zones in a semiconductor structure.

According to a further embodiment, at least one quantum structure of an active zone of indium aluminum gallium arsenide, InAlGaAs, or of gallium arsenide phosphide, GaAsP, is particularly preferably formed. A mixture of the various compound semiconductors and further compound semiconductors for producing the quantum structures is likewise conceivable.

It is also possible to provide a semiconductor structure with a plurality of active zones, of which at least one is conventionally formed, while at least one further, using the principle according to the invention, ie. H. is formed using a plurality of different compound semiconductors for realizing a quantum structure.

In a further advantageous embodiment, it is provided that the semiconductor structure is arranged on an n-type substrate, that two quantum wells each formed as a quantum well are provided, wherein the first quantum well formed of Galliumarsenidphosphid and in a layer structure of the semiconductor structure closer to the n-type substrate is arranged as the second quantum film formed of indium aluminum gallium arsenide. This configuration is particularly advantageous for the production of the layer structure in the case of the growth of relatively large structures (SLOCs), since stresses occurring in the growth, which can cause defects in the material, are advantageously reduced before they can reach critical values. In addition, it can be assumed that electrons can more easily overcome a normally thicker quantum structure of gallium arsenide phosphide than holes.

An inverse layer structure, in turn, in which two quantum wells each formed in turn quantum wells are provided, wherein the first quantum well of Galliumarsenidphosphid formed and arranged in a layer structure of the semiconductor structure farther away to the n-type substrate than the second quantum well formed of Indiumaluminiumgalliumarsenid is, can In contrast, have a better thermal behavior, since the emission of electrons is braked on a p-side of the layer assembly.

In a further advantageous embodiment, it is provided that the semiconductor structure is designed as an edge emitter and / or as a vertically emitting surface emitter, VCSEL. Depending on the configuration corresponding end or surfaces of the light emitting semiconductor structure with corresponding further layer such. B. antireflection layers to provide or possibly existing current contacts for impressing an operating current in such a way that the generated radiation can escape at the desired locations of the semiconductor structure.

In a further advantageous embodiment, it is provided that the semiconductor structure is designed as a light-emitting diode or as a laser diode. In the case of the laser diode, the person skilled in per se known arrangements for the formation of an optical resonator in the semiconductor structure to meet. Furthermore, suitable waveguide structures are to be formed, which can be realized, for example, in the form of a corresponding design of the jacket layer structure with specific refractive index profiles, etc.

Particularly preferably, the quantum structure has a maximum extent of approximately 20 nanometers (nm) in at least one length dimension. For a quantum film, for example, this corresponds to a layer thickness of the quantum film of about 20 nm or less. Accordingly, double or triple quantum films can advantageously have a maximum layer thickness of about 40 nm or about 60 nm.

The light-emitting semiconductor structure according to the invention can advantageously also be used to form a semiconductor device having a plurality of identical or differently configured semiconductor structures. In particular, an edge-emitting semiconductor laser structure having a plurality of radiation sources can be constructed in this way, wherein the individual radiation sources are formed by the light-emitting semiconductor structures according to the invention. The radiation fields of the individual radiation sources can be both coupled and uncoupled, which can be controlled in a manner known to those skilled in the art by the provision of barrier layers between the individual semiconductor structures.

As a further solution to the object of the present invention, a semiconductor device according to claim 9 is proposed. The semiconductor device has a layer structure of a plurality of light-emitting semiconductor structures, wherein each semiconductor structure has a cladding layer structure and at least one active zone arranged in the cladding layer structure with at least one quantum structure for generating electromagnetic radiation.

According to the invention, active zones of at least two different semiconductor structures of the semiconductor device have quantum structures of different compound semiconductors in each case. Alternatively or additionally, at least one semiconductor structure according to one of claims 1 to 7 is formed.

Advantageous embodiments are the subject of the dependent claims.

Further advantages, features and details will become apparent from the following description in which, with reference to the drawings, various embodiments of the invention are shown. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination.

In the drawing shows

1 FIG. 2 shows a partial cross section through an embodiment of a semiconductor light-emitting structure for forming an active zone, FIG.

2 a partial cross section of a multi-edge emitter semiconductor structure according to another embodiment of the invention,

3a - 3c Various embodiments of quantum structures for use in the semiconductor structures according to 1 . 2 , and

4 a side view of a semiconductor device according to another embodiment.

1 shows a plan view of an end face of a semiconductor light-emitting structure 100 , The semiconductor structure 100 is on an n-type substrate 300 arranged and has a jacket layer structure 110a . 110b on and one between the two cladding layers 110a . 110b arranged active zone 112 ,

The active zone 112 In the present case, there are two quantum structures each formed as a quantum film 112a . 112b on. In the quantum structures 112a . 112b the active zone 112 In a manner known per se, a generation of electromagnetic radiation (light) by recombination of charge carriers takes place. According to one aspect of the invention are the quantum films 112a . 112b formed of different compound semiconductors.

Preferably, the first quantum film 112a for example, tensile gallium arsenide phosphide, GaAsP, while the second quantum well 112b made of pressure-strained indium aluminum gallium arsenide, InAlGaAs. A layer thickness of the first quantum film 112a is preferably between about 10 nm and about 20 nm, while a layer thickness of the second quantum film 112b between about 5 nm and about 10 nm. 3a shows a cross section through the active zone 112 in detail with an indication of the layer thickness of the first quantum film 112a through the unspecified double arrow.

In addition to the use of GaAsP and InAlGaAs, other compound semiconductors can also be used to form the quantum structures 112a . 112b be used. 3b shows a partial cross section through an active zone 112 ' according to another embodiment, wherein a first layered quantum structure is defined by two volume regions 112c ' . 112c '' is formed, which consist of different compound semiconductors. In that regard, the layer realized 112c ' . 112c '' as it were a "hybrid quantum film". In addition - in accordance with 3a - another quantum film 113 in the active zone 112 ' be provided, for example, consists entirely of a third semiconductor material or also a hybrid structure as the layer 112c ' . 112c '' having.

3c shows a cross section through an active zone 112 '' according to a further embodiment, wherein a layered quantum structure of a plurality of juxtaposed quantum wires 112d . 112e is formed, which preferably each consist of different compound semiconductors. It is understood that the quantum wires 112d . 112e not necessarily have the same layer thickness d.

In addition to the above-exemplified configurations, the semiconductor light-emitting structure can 100 ( 1 ) also several active zones 112 . 112 ' . 112 '' whose specific training in each case in particular by the examples of 3a . 3b . 3c may differ. Quantum wires and / or quantum dots or combinations thereof may be used instead of quantum films to form one or more active zones.

The inventive combination of different compound semiconductors for forming the quantum films 112a . 112b or in general the quantum structure (s) of the active zone 112 has the advantage that the respective properties of the relevant compound semiconductor in the semiconductor structure 100 be combined. Especially when growing relatively large layer thicknesses 112a . 112b For example, according to the SLOC (Super Large Optical Confinement) principle, growth can lead to critical stresses, the defects in the material of the semiconductor structure 100 trigger. By the above-described combination of quantum wells 112a . 112b made of different materials, the tension can be counteracted advantageous.

According to the invention, it has been recognized that a particularly expedient configuration is the use of an n-type substrate 300 It is understood that the closer to the n-type substrate 300 located first quantum film 112a ( 1 ) is formed of GaAsP while the second quantum film 112b is made of InAlGaAs. This combination enables a particularly advantageous reduction of stresses during the production of the layer structure of the semiconductor structure 100 ,

A current contact 210 on a p-type side of the semiconductor structure 100 is also in 1 shown. It serves to impress an operating current in the semiconductor structure 100 , The arrows 220 indicate a current flow from the current contact 210 to the n-type substrate 300 on how he deals with the operation of the semiconductor structure 100 results. The resulting light distribution is also in 1 indicated, compare the ellipse 230 ,

The the active zone 112 ( 1 ) limiting cladding layers 110a . 110b In known manner, waveguide layers for guiding the generated electromagnetic radiation may also be used.

In general, the light-emitting semiconductor structure 100 be used advantageously for the realization of light-emitting diodes (LED) or of laser diodes. For the formation of the light-emitting semiconductor structure 100 For example, suitable mirror layers (not shown) which define a corresponding optical resonator are to be provided as laser diode.

The light-emitting semiconductor structure 100 According to a further embodiment, for example, be formed as so-called. Edge emitter, wherein the generated electromagnetic radiation predominantly by the in 1 imaged end face of the structure, ie in 1 from the plane of the drawing, is delivered, cf. also the light distribution 230 , Alternatively or additionally, the semiconductor structure 100 also be configured such that it emits generated electromagnetic radiation at least partially over a surface other than its front surface, for example, by type of a VCSEL laser by an in 1 upper surface, on which also the current contact 210 is arranged.

The above with reference to 1 described light-emitting semiconductor structure 100 can also be beneficial with other similar structures 100 - or with different structures - are combined, cf. 4 , This leads to a semiconductor device 1000 with, for example, four light emitters 100 in stack configuration, which may preferably be formed as edge emitter. Each semiconductor structure 100 according to 4 is as above with reference to 1 described trained. It is also conceivable that different semiconductor structures 100 the stack configuration 1000 each differently formed active zones 112 ( 1 ), z. B. with different materials and / or types of quantum structures and / or number of active zones. The stack configuration 1000 again preferably has a substrate 300 on. The multiple semiconductor structures 100 the arrangement 1000 can be connected to each other in a conventional manner by means of tunnel diodes.

According to a further advantageous embodiment, more than two quantum structures per active zone may be provided, or even a single quantum structure consisting of a mixture of different compound semiconductors. In the present case, the term "mixture" is understood to mean any combination of different suitable semiconductor materials for forming a quantum structure. In particular, "mixture" also denotes a layer structure of several layers of different materials ( 3a . 3b ), the formation of a single layer of different materials ( 3c ) and other material combinations. For example, a quantum structure according to the invention can also be produced by virtue of the fact that different volume regions of an active zone, which can also be statistically distributed, each with different material, such as e.g. B. the compound semiconductors already mentioned several times, are made.

2 shows a semiconductor device 2000 according to a further embodiment. The semiconductor device 2000 has a layer structure of a plurality of stacked light-emitting semiconductor structures formed by way of example as edge emitters 200 . 200 ' on. The edge emitter 200 . 200 ' are interconnected by a tunnel diode 215 connected.

The arrows 220 give a current flow from the current contact 210 to the n-type substrate 300 on how he is in the operation of the semiconductor device 2000 established. A corresponding light distribution is through the ellipses 230a . 230b indicated.

According to the invention, both edge emitters 200 . 200 ' in each case a first and a second cladding layer for receiving an active zone 212a . 212a ' on. In that regard, the edge emitter correspond 200 . 200 ' in their construction of the structure 100 out 1 , Each of the two edge emitters 200 . 200 ' has an active zone disposed between the cladding layers 212a . 212a ' on. The active zones 212a . 212a ' each have at least one quantum structure, for example a quantum film, which in 2 indicated by horizontal, dashed lines.

A first advantageous embodiment of the semiconductor device 2000 according to the active zones 212a . 212a ' the two different edge emitters 200 . 200 ' Quantum films from each different compound semiconductors. That means the first edge emitter 200 for example, has an active zone 212a with a quantum film consisting of indium aluminum gallium arsenide while the active zone 212a ' of the second edge emitter 200 ' has a quantum well of gallium arsenide phosphide.

It is also conceivable that the semiconductor device 2000 more than two edge emitters 200 . 200 ' or in general light-emitting semiconductor structures, wherein in turn at least two semiconductor structures or edge emitters each have active zones with differently designed quantum structures, for example quantum films.

Another embodiment provides a semiconductor device 2000 with stacked structure, in which at least one semiconductor light-emitting structure according to the above with reference to 1 to 3c described configurations 100 is trained.

In particular, it is possible for an active zone 212a at least one edge emitter 200 ' has a quantum structure consisting of a mixture of different compound semiconductors, such as indium aluminum gallium arsenide or gallium arsenide phosphide.

In a particularly preferred embodiment of the semiconductor device 2000 according to 2 is the active zone 212a ' of in 2 upper edge emitter 200 ' formed from gallium arsenide phosphide, while the active zone 212a of in 2 lower edge emitter 200 is formed of indium aluminum gallium arsenide.

As on the surfaces of semiconductor devices, as for example by the semiconductor device 2000 are formed, preferably defects occur, it is conceivable that at a separation trench 2100 that the semiconductor device 2000 from a neighboring semiconductor device (not shown) separates various defects 2200 . 2300 arise. In the in 2 upper active zone 212a ' is due to the less wide light distribution 230a a relatively large distance between the defect 2300 and the current-carrying region of the edge emitter 200 ' given. In the lower active zone 212a is due to the opposite to the upper active zone 212a ' wider light distribution 230b a relatively small distance between the defect 2200 and the current-carrying area or the light distribution 230b given. This is in the lower active zone 212a an increased risk of that defect 2200 over time into the current-carrying area of the edge emitter 212a spreads and there, for example, a semiconductor laser forming structure 200 destroyed. Because the lower active zone 212a However, according to a preferred embodiment, it has a quantum film of indium aluminum gallium arsenide, the defect migration of the defect 2200 braked advantageous, so that the defect 2200 the current-carrying region of the edge emitter 200 reached only after a very long time. Due to the greater distance between the defect 2300 and the light distribution 230a or the current-carrying area of the in 2 upper edge emitter 200 ' can for the active zone 212a ' of the edge emitter 200 ' Advantageously, another compound semiconductor, namely gallium arsenide phosphide in particular, can also be used to form the quantum film, although GaAsP does not have as good a resistance to defect propagation as InAlGaAs.

According to another embodiment of the invention, it is also possible to form a semiconductor device having a plurality of edge emitters, or generally light emitting semiconductor structures, such that an active region of a first edge emitter consists of a first compound semiconductor, for example gallium arsenide phosphide, and an active region of a second edge emitter a mixture of gallium arsenide phosphide and indium aluminum gallium arsenide. In turn, a third edge emitter of the structure may have an active zone with gallium arsenide phosphide quantum structures.

• 1. Indiumaluminiumgalliumarsenid (1. Kantenemitter),
• 2. einer Mischung aus Galliumarsenidphosphid und Indiumaluminiumgalliumarsenid (2. Kantenemitter) und
• 3. Indiumaluminiumgalliumarsenid (3. Kantenemitter).

It is likewise possible to use a semiconductor arrangement with at least three stacked edge emitters whose active structures or quantum structures are each formed from:

• 1. indium aluminum gallium arsenide (1st edge emitter),
• 2. a mixture of gallium arsenide phosphide and indium aluminum gallium arsenide (2nd edge emitter) and
• 3. Indium aluminum gallium arsenide (3rd edge emitter).

A further advantageous embodiment may, for example, have a first edge emitter with an active zone comprising at least one gallium arsenide phosphide quantum structure. Another edge emitter may comprise an active region having one or more quantum structures consisting of a mixture of gallium arsenide phosphide and indium aluminum gallium arsenide, and a third edge emitter may comprise an active region having at least one indium aluminum gallium arsenide quantum structure. In principle, the sequence of the compound semiconductor materials used for the realization of the quantum structures in the stack construction is arbitrary and can be selected, for example, depending on application-related or manufacturing-technical aspects.

It is also conceivable according to the invention to provide a semiconductor device having a plurality of edge emitters, whose relevant active zones each have one or more quantum structures comprising a mixture of gallium arsenide phosphide and indium aluminum gallium arsenide. The use of further compound semiconductors and mixtures thereof for the formation of the quantum structures is also conceivable.

The application of the principle according to the invention is not limited to edge emitting semiconductor structures, it may also surface emitting elements, for. B. in the sense of a VCSEL architecture provided. By appropriate measures such. B. Provision of waveguides and / or cladding layer structures (eg., By different refractive index profiles) and / or optical resonators, the light-emitting semiconductor structures according to the invention z. B. be designed as an LED type or as a laser diode.

Particularly preferably, the quantum structure of the semiconductor light-emitting structure 100 . 200 . 200 ' in at least one length dimension, a maximum extension of about 20 nanometers (nm). For a quantum film 112a ( 3a ), this corresponds, for example, to a layer thickness of the quantum film of about 20 nm or less. The same applies to quantum wires or quantum dots.

The providence of InGaAsP-based quantum structures, which, depending on the layer structure, can be combined with compressive strain as well as with tensile stress in the semiconductor structure 100 can be integrated in combination with GaAs or other types of quantum structures advantageously allows the generation of electromagnetic radiation of different polarization directions.

Claims (10)

Light-emitting semiconductor structure ( 100 ) having a cladding layer structure ( 110a . 110b ) and at least one in the cladding layer structure ( 110a . 110b ) arranged active zone ( 112 ) containing at least one quantum structure ( 112a . 112b ) for generating electromagnetic radiation, characterized in that the at least one quantum structure ( 112a . 112b ) is formed of various compound semiconductors. Semiconductor structure ( 100 ) according to claim 1, wherein the quantum structure ( 112a . 112b ) is designed as a quantum dot and / or as a quantum wire and / or as a quantum film, characterized in that a first volume region of the quantum structure ( 112a . 112b ) is formed from a first compound semiconductor material and that a second volume region of the quantum structure ( 112a . 112b ) is formed of a second compound semiconductor material. Semiconductor structure ( 100 ) according to one of the preceding claims, characterized in that at least one quantum structure ( 112a ) is formed of indium aluminum gallium arsenide, InAlGaAs, or gallium arsenide phosphide, GaAsP, or a mixture of indium aluminum gallium arsenide and gallium arsenide phosphide and / or at least one other compound semiconductor material. Semiconductor structure ( 100 ) according to one of the preceding claims, characterized in that the semiconductor structure ( 100 ) on an n-type substrate ( 300 ) is arranged such that two quantum structures each formed as a quantum film ( 112a . 112b ), wherein the first quantum film ( 112a ) formed of gallium arsenide phosphide and in a layer structure of the semiconductor structure ( 100 ) closer to the n-type substrate ( 300 ) is arranged as the second quantum film ( 112b ) formed of indium aluminum gallium arsenide. Semiconductor structure ( 100 ) according to one of the preceding claims, characterized in that the semiconductor structure ( 100 ) is designed as an edge emitter and / or as a vertically emitting surface emitter, VCSEL. Semiconductor structure ( 100 ) according to one of the preceding claims, characterized in that the semiconductor structure ( 100 ) is designed as a light emitting diode or as a laser diode. Semiconductor structure ( 100 ) according to one of the preceding claims, characterized in that the quantum structure ( 112a . 112b ) in at least one length dimension has a maximum extension of about 20 nanometers, nm. Semiconductor arrangement ( 1000 ) having a plurality of semiconductor structures ( 100 ) according to any one of the preceding claims. Semiconductor arrangement ( 2000 ) with a layer structure comprising a plurality of light-emitting semiconductor structures ( 200 . 200 ' ), each semiconductor structure ( 200 . 200 ' ) a cladding layer structure and at least one active zone arranged in the cladding layer structure ( 212a . 212a ' ) having at least one quantum structure for generating electromagnetic radiation, characterized in that a) active zones of at least two different semiconductor structures ( 200 . 200 ' ) Have quantum structures of respectively different compound semiconductors and / or that b) at least one semiconductor structure ( 200 ) is designed according to one of claims 1 to 7. Semiconductor arrangement ( 2000 ) according to claim 9, characterized in that at least one quantum structure ( 212a ) is formed of indium aluminum gallium arsenide, InAlGaAs, or gallium arsenide phosphide, GaAsP, or a mixture of indium aluminum gallium arsenide and gallium arsenide phosphide and / or at least one other compound semiconductor material.

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