EP2248192A1

EP2248192A1 - Optoelectronic semiconductor body with a tunnel junction and method for producing such a semiconductor body

Info

Publication number: EP2248192A1
Application number: EP09715687A
Authority: EP
Inventors: Martin Strassburg; Lutz Höppel; Matthias Sabathil
Original assignee: Osram Opto Semiconductors GmbH
Current assignee: Ams Osram International GmbH
Priority date: 2008-02-29
Filing date: 2009-02-26
Publication date: 2010-11-10
Also published as: DE102008028036A1; US20110012088A1; CN101960622B; CN101960622A; KR20100126458A; TWI404232B; WO2009106070A1; JP2011513960A; TW200945637A

Abstract

The invention specifies an optoelectronic semiconductor body having an epitaxial semiconductor layer sequence which has a tunnel junction (2) and an active layer (4) which is intended to emit electromagnetic radiation. The tunnel junction has an intermediate layer (23) between an n-type tunnel junction layer (21) and a p-type tunnel junction layer (22). In one embodiment, the intermediate layer has an n-type barrier layer (231) facing the n-type tunnel junction layer, a p-type barrier layer (233) facing the p-type tunnel junction layer and a middle layer (232). The material composition of the middle layer differs from the material composition of the n-type barrier layer and the p-type barrier layer. In another embodiment, the intermediate layer (23) is alternatively or additionally deliberately provided with defects (6). A method for producing such an optoelectronic semiconductor body is also specified.

Description

Confession

Optoelectronic semiconductor body with tunnel junction and method for producing such

The present application relates to an optoelectronic semiconductor body with tunnel junction and a method for producing such.

This patent application claims the priorities of German patent application 10 2008 011 849.4 and German patent application 10 2008 028 036.4, the disclosure of which is hereby incorporated by reference.

An optoelectronic semiconductor body with tunnel junction is known, for example, from the publication WO2007 / 012327 A1.

It is an object of the present application to specify an optoelectronic semiconductor body with an improved tunnel junction.

This object is achieved by an optoelectronic semiconductor body and a method for producing an optoelectronic semiconductor body according to the independent patent claims. Advantageous embodiments and further developments of the semiconductor body and the method are specified in the respective dependent claims. The disclosure of the claims is hereby expressly incorporated by reference to the description. An optoelectronic semiconductor body with an epitaxial semiconductor layer sequence is specified. The epitaxial semiconductor layer sequence has a tunnel junction and an active layer provided for the emission of electromagnetic radiation. The tunnel junction includes an intermediate layer between an n-type tunnel junction layer and a p-type tunnel junction layer.

The term "tunnel junction layer" is used to distinguish it from the remaining semiconductor layers of the semiconductor body and means that the n-conductive or p-conductive layer is contained in the region of the semiconductor layer sequence called the tunnel junction , Thus, at least by means of the n-type tunnel junction layer, the p-type tunnel junction layer and in the present case also by means of the intermediate layer, a suitable for the tunneling of charge carriers electrical potential profile caused.

In one embodiment, the intermediate layer has an n-type barrier layer facing the n-type tunnel junction layer, a p-type barrier layer facing the p-type tunnel junction layer, and a middle layer. The material composition of the middle layer differs from the material composition of the n-barrier layer and the material composition of the p-barrier layer.

In one embodiment, the intermediate layer, that is to say in particular the n-barrier layer, the middle layer and the p-barrier layer, has a semiconductor material which contains a first and a second component. Preferably, the Proportion of the first component in the middle layer smaller than in the n-barrier layer and / or in the p-barrier layer. In a further development, the first component contains aluminum or the first component consists of aluminum. In another development, the second component contains at least one of the following elements: In, Ga, N, P. For example, the intermediate layer has the

Semiconductor material AlInGaN on, and the first component is aluminum and the second component InGaN.

"If the semiconductor material AlInGaN has this" means in the present context that the intermediate layer, preferably also the active layer, has or consists of a nitride compound semiconductor material, preferably Al _n In _ra Ga _n - _m N, where O ≦ _n ≦ l, 0 ≤ m ≤ 1 and n + m ≤ 1. However, this material does not necessarily have to have a mathematically exact composition according to the above formula. Rather, it may, for example, have one or more dopants and additional constituents. For the sake of simplicity, however, the above formula contains only the essential constituents of the crystal lattice (Al, In, Ga, N), even if these can be partially replaced and / or supplemented by small amounts of further substances.

In a further embodiment, the proportion of the first component, that is, for example, the aluminum content, in the middle layer is less than or equal to 20 percent. In the n-barrier layer and / or the p-barrier layer, the proportion of the first component is in particular greater than or equal to 20 percent. For instance, applies to this embodiment, and the material of Al _n In _m Gai_ _n - _m N or Al _n Ga _m In _1-n -MP for the aluminum content in the center layer n: n ≤ 0.2 and in particular in the n-barrier layer and / or the p-barrier layer: n ≥ 0.2.

A layer thickness of the n-barrier layer and / or a layer thickness of the p-barrier layer is in an advantageous embodiment less than or equal to 2 nm. For example, it is between 0.3 nm and 2nm, in particular between 0.5 nm and 1 nm, wherein the Borders are included. In one advantageous embodiment, a layer thickness of the middle layer has a value between 1 nm and 8 nm, preferably between 2 nm and 4 nm, the limits being included in each case.

By means of the intermediate layer, which has an n-barrier layer, a p-barrier layer and a middle layer whose material composition differs from the material composition of the n-barrier layer and / or the p-barrier layer, improved electronic properties of the tunnel junction can be achieved.

For example, a diffusion of an n-type dopant from the n-type tunnel junction layer in the direction of the p-type tunnel junction layer and / or a diffusion of a p-type dopant from the p-type through the n-type barrier layer and / or through the p-type barrier layer Tunnel junction layer towards the n-type tunnel junction layer reduced. By means of the n-barrier layer and / or the p-barrier layer, the risk of a compensation of acceptors and donors is thus reduced, which negatively influences the tunnel properties. In particular, the middle layer has a smaller bandgap than the n-barrier layer and / or the p-barrier layer, for example because of the smaller proportion of the first component of the semiconductor material. On In this way, a particularly high probability of tunneling of the charge carriers through the intermediate layer is advantageously achieved.

Calculations by the inventors have shown that in the case of an intermediate layer with an n-barrier layer and / or a p-barrier layer whose layer thickness is in particular less than or equal to 2 nm, and with a middle layer deviating material composition, strong polarization charges can be generated, resulting in a particularly high Carrier density in the n-type tunnel junction layer and / or the p-type tunnel junction layer can be caused.

In this way, a high concentration of electrons in the n-type tunnel junction layer and / or holes in the p-type tunnel junction layer can advantageously be achieved. Advantageously, the n-type tunnel junction layer and / or the p-type tunnel junction layer in particular thus a particularly large transverse conductivity, so that a particularly good lateral StromaufWeitung can be achieved. In this way, a laterally particularly homogeneous distribution of the charge carriers can advantageously be achieved. The area which is available to the charge carriers for tunnel junctions is therefore particularly large. Thus, a tunnel junction with a particularly low electrical resistance and an optoelectronic semiconductor body with a particularly low forward voltage can be achieved.

In a further embodiment, the intermediate layer between the n-type tunnel junction layer and the p-type tunnel junction layer of the tunnel junction is specifically provided with impurities. Does the intermediate layer have a p- Barrier layer, a middle layer and an n-barrier layer, the intermediate layer is specifically provided with the impurity in an embodiment in the region of the middle layer.

By means of the impurities, energetic states are generated within the band gap in the region of the intermediate layer, which is provided with the impurities. By means of these additional states, the tunneling probability for carriers can be increased through the tunnel junction, so that an increased transition rate of electrons and / or holes through the intermediate layer can be achieved. The additional states act in particular as so-called tunnel centers.

The impurities are for example at least partially formed by defects of a semiconductor material of the intermediate layer. In particular, a defect density, that is to say the number of defects per volume, in the area of the intermediate layer specifically provided with impurities, is opposite a region of the intermediate layer which follows the area specifically provided with impurities, and / or with respect to a region of the intermediate layer which is specifically intended Accident provided area precedes, increases. For example, the defect density in the region provided with impurities is at least twice as large, preferably at least five times as large and in particular at least ten times as large as in the preceding and / or subsequent region of the intermediate layer. In one embodiment, the defect density in the region provided with impurities has a value of greater than or equal to 10 ¹⁵ cm ^-3 , preferably of greater than or equal to 10 ¹⁶ cm ^-3 . For example, it has a value of 10 ¹⁷ cm ^"3 or more. The specifically provided with an impurity region and the this subsequent and / or preceding region of the intermediate layer in this case have in an embodiment of the same material composition. In one embodiment, also this in addition to the specifically provided with an impurity region preceding and / or the subsequent region of the intermediate layer, which has a lower defect density, in the middle layer between the n-barrier layer and the p-barrier layer.

In another embodiment, the impurities are at least partially formed by foreign atoms. In the present case, atoms and / or ions which in the semiconductor material of the intermediate layer are usually neither referred to as the main constituent (for example Al, Ga, In or N ions in the semiconductor material AlInGaN) nor as the p-type dopant or n, are referred to as "foreign atoms" Dopant are used.

It is advantageous if the energetic position of the additional states caused by the impurities is located approximately in the middle of the band gap. Such states are also called deep impurities or "midgap states." In the case of impurities formed by impurities, especially metals, transition metals, and / or rare earths are suitable as foreign atoms, for example chromium, iron and / or manganese atoms can be used as impurities Pt atoms, for example, are suitable as impurity atoms, whereas n-dopants such as silicon or p-type dopants such as magnesium generally generate states that are not in the middle of the band gap but close to a band edge. The foreign atoms may be incorporated in the crystal lattice of the semiconductor material of the intermediate layer, for example as substitution atoms and / or as interstitial atoms. Alternatively or additionally, the foreign atoms may also be contained as a layer in the intermediate layer. The layer of foreign atoms is preferably not closed. Rather, it has in particular openings, which are penetrated by the semiconductor material of the intermediate layer. In other words, the semiconductor material of the intermediate layer passes through the openings of the layer of impurity atoms from the n-side of the tunnel junction to the p-side of the tunnel junction.

The foreign atoms contained in the area of the intermediate layer specifically provided with impurities are present there in a configuration in a concentration of between 10 ¹⁵ l / cm ³ and 10 ¹⁹ l / cm ³ , the limits being included. With a higher concentration of impurities there is a risk that the quality of the semiconductor material is reduced. In particular, the tunneling current increases disproportionately with concentrations of the foreign atoms.

One of the n-type tunnel junction layer and / or an edge region of the intermediate layer adjacent to the p-type tunnel junction layer is free of the deliberately introduced impurities in one embodiment. In the case of a semiconductor body whose intermediate layer contains an n-barrier layer, a middle layer and a p-barrier layer, in particular an edge region of the middle layer adjacent to the n-barrier layer and / or an edge region of the middle layer adjacent to the p-barrier layer are free of the targeted introduction Impurities. In a further embodiment, the intermediate layer is provided with the impurities approximately in the middle between the n-type tunnel junction layer and the p-type tunnel junction layer. Such an extent and location of the impurities is advantageous for the crystal quality of the intermediate layer.

In one embodiment of the semiconductor body, the intermediate layer is nominally undoped. In another embodiment, the intermediate layer is p-doped at least in places. In a further development, the middle class is p-doped. By "nominally undoped" herein is meant that the concentration of an n-type dopant and a p-type dopant is at most 0.1 times, preferably at most 0.05 times as large and in particular at most 0.01 times as large as the concentration For example, the concentration of the n-type dopant or p-type dopant in the nominally undoped layer is less than or equal to 1 × 10 ¹⁸ atoms / cm ³ , preferably less than or equal to 5 x 10 ¹⁷ atoms / cm ³ , in particular it is less than or equal to 1 x 10 ¹⁷ atoms / cm ³ .

The n-type tunnel junction layer and / or the p-type tunnel junction layer are designed as superlattices of alternating layers in one embodiment. For example, it is an InGaN / GaN superlattice. With such a superlattice, a further increase in the charge carrier concentration in the n-type tunnel junction layer or the p-type tunnel junction layer can be achieved. So can the lateral Current expansion and the tunneling rate through the tunnel junction are further increased.

In an expedient refinement, the epitaxial semiconductor layer sequence of the optoelectronic semiconductor body has an n-type layer, the tunnel junction, a p-type layer, the active layer and a further n-type layer in this order.

In another embodiment, the epitaxial semiconductor layer sequence is based on a III / V compound semiconductor material, for example on the semiconductor material AlInGaN. An Ill / V compound semiconductor material comprises at least one element of the third main group such as B, Al, Ga, In, and a fifth main group element such as N, P, As. In particular, the term "III / V compound semiconductor material" includes the group of binary, ternary or quaternary compounds containing at least one element from the third main group and at least one element from the fifth main group, for example AlInGaN or AlInGaP. Ternary or quaternary compound may also have, for example, one or more dopants and additional ingredients.

In a method for producing an optoelectronic semiconductor body with an epitaxial

A semiconductor layer sequence comprising a tunnel junction and an active layer provided for emission of electromagnetic radiation, wherein the tunnel junction comprises an n-type tunnel junction layer, an intermediate layer and a p-type layer. Tunneling layer has, for producing the intermediate layer, a semiconductor material - epitaxially deposited - in particular in an epitaxial reactor. The semiconductor material of the intermediate layer is at least selectively provided with impurities.

In one embodiment, the provision of defects includes introducing defects into the semiconductor material. For example, to introduce the defects during the deposition of the semiconductor material in the epitaxial reactor at least temporarily hydrogen gas is passed into the epitaxial reactor.

The amount of hydrogen gas introduced, in one embodiment, is from 0.1% to 50% inclusive of that amount of hydrogen gas intended to grow silicon-doped gallium nitride (GaN: Si) with trimethylgallium (TMGa) as a precursor in the epitaxial reactor is. The amount of hydrogen which is provided for the growth of GaN: Si with TMGa as precursor is generally specified by the manufacturer of the epitaxy reactor and thus known in principle to the person skilled in the art. In a further embodiment, the hydrogen gas is passed into the epitaxy reactor in an amount of between 0.1 standard liter per minute (slpm) and 20 slpm, preferably between 1 slpm and 10 slpm, in particular between 2 slpm and 5 slpm, the limits being respectively are included. In another embodiment, the hydrogen gas is passed into the epitaxy reactor in an amount of six standard cubic centimeters per minute (6 sccm) or more. The introduction of the hydrogen gas is preferably carried out only over a short period of time, for example, ten minutes or less, preferably two minutes or less, more preferably one minute or less.

In another embodiment of the method, during the deposition of the semiconductor material in the epitaxy reactor for introducing the defects, a process temperature and / or a pressure in the epitaxy reactor is changed. For example, the temperature is changed at a rate greater than or equal to 60 ^° C. per minute and / or the pressure is changed at a rate greater than or equal to 100 mbar per minute. The change can be gradual or continuous, as so-called temperature and / or pressure ramp. The time duration of the temperature and / or pressure change is 120 seconds or less in a further development.

In another embodiment, the intermediate layer is alternatively or additionally provided with impurities by foreign atoms are introduced into the intermediate layer. For example, the impurities and the semiconductor material are deposited at the same times, such as by the fact that the sources which provide the semiconductor material and the foreign atoms are temporarily operated simultaneously. In this way, in one embodiment, incorporation of the foreign atoms into the crystal lattice of the semiconductor material takes place.

Alternatively, first the semiconductor material is deposited to form a first part of the intermediate layer, then the impurities are deposited as a layer on the first part and finally the semiconductor material is deposited again to form a second part of the intermediate layer. The second part of the In particular, the intermediate layer is deposited in such a way that it substantially completely covers the layer of the foreign atoms and the first part of the intermediate layer.

The deposition of the layer of foreign atoms is in particular such that it has openings. For example, the deposition of the foreign atoms is stopped before a closed layer is deposited. Alternatively, first of all a closed layer of foreign atoms can be produced and then subsequently removed in places, for example by means of an etching process such as reactive ion etching (RIE). The layer of foreign atoms, which in particular has openings, in one embodiment has a layer thickness between 0.1 nm and 10 nm, preferably between 0.1 nm and 3 nm.

The second part of the intermediate layer is expediently deposited in such a way that it adjoins the first part of the intermediate layer in the region of the openings of the layer of foreign atoms. In particular, the layer thickness of the layer of foreign atoms is selected so that the second part epitaxially overgrows the layer of foreign atoms.

Further advantages and advantageous embodiment of the optoelectronic semiconductor body and the method will become apparent from the following in connection with the figures illustrated embodiments.

Show it:

FIG. 1, a schematic sectional representation of an optoelectronic semiconductor body according to a first exemplary embodiment, FIG. 2 shows a schematic sectional representation of an optoelectronic semiconductor body according to a second exemplary embodiment,

FIG. 3, a schematic sectional illustration of an optoelectronic semiconductor body according to a third exemplary embodiment,

FIG. 4, a schematic representation of the band structure and the carrier density in the semiconductor body according to the first exemplary embodiment,

5A, a schematic representation of the band structure in the semiconductor body according to the second embodiment,

Figure 5B, a schematic representation of

Carrier density in the semiconductor body according to the second embodiment, and

6, a schematic representation of the band structure in the semiconductor body according to the third embodiment.

In the figures, similar or similar components are provided with the same reference numerals. The figures and the proportions of the elements shown in the figures with each other are not to be considered to scale, unless units of measurement are explicitly stated. Rather, individual elements, for example layers, for exaggerated representability and / or better understanding may be exaggerated. The Band structures and carrier densities are highly schematic and simplified.

FIG. 1 shows a schematic sectional representation through an optoelectronic semiconductor body according to a first exemplary embodiment. The semiconductor body is based, for example, on the semiconductor material AlInGaN.

In the present case, the optoelectronic semiconductor body has an n-conducting layer 1, a tunnel junction 2, a p-conducting layer 3, an active layer 4 and a further n-conducting layer 5, which follow one another in this order.

The active layer 4 preferably has a pn junction, a double heterostructure, a single quantum well (SQW) or a multiple quantum well structure (MQW) for generating radiation. The term quantum well structure unfolds no significance with regard to the dimensionality of the quantization. It thus includes u.a. Quantum wells, quantum wires and quantum dots and any combination of these structures. Examples of MQW structures are described in the publications WO 01/39282, US 5,831,277, US 6,172,382 Bl and US 5,684,309, the disclosure content of which is hereby incorporated by reference.

For example, the growth direction of the semiconductor body is directed from the n-type layer 1 to the p-type layer 3. The further n-type layer 5 follows the active layer 4 in this case in the growth direction, while the p-type layer 3 precedes the active layer 4. In this way, the polarity of the optoelectronic semiconductor body in Comparison to a semiconductor body without tunnel junction 2 inverted. In this way, an advantageous alignment of piezoelectric fields in the semiconductor material is achieved.

The tunnel junction has an n-type tunnel junction layer 21 which faces the n-type layer 1. It further has a p-type tunnel junction layer 22 facing the p-type layer 3. Between the n-type tunnel junction layer 21 and the p-Tγp tunnel junction layer 22, an intermediate layer 23 is arranged.

In the course of the n-type tunnel junction layer 21 to the p-type tunnel junction layer 22, the intermediate layer 23 has an n-type barrier layer 231, a middle layer 232 and a p-type barrier layer 233.

By way of example, the n-type layer 1 is a GaN layer which is n-doped with silicon. The silicon is present, for example, in a concentration between 1 × 10 ¹⁹ atoms / cm ³ and 1 × 10 ²⁰ atoms / cm ³ in the n-type layer. The p-type layer, for example, is likewise a GaN layer which is p-doped with magnesium, in particular in a dopant concentration between 1 × 10 ¹⁹ atoms / cm ³ and 2 × 10 ²⁰ atoms / cm ³ in the p-type layer 3 is present. The limits of the specified ranges are included here.

In the present case, the n-type tunnel junction layer 21 is an InGaN layer which, for example, has an indium content between 0 and 15 percent (0 <m ≦ 0.15 in the formula Al _n In _m Ga _{n n} _m ) , It is also n-doped with silicon, again with a concentration, for example between and including 1 x 10 ¹⁹ atoms / cm ³ and including 1 x 10 ²⁰ atoms / cm ³ . The p-type tunnel junction layer 22 is presently also an InGaN layer containing, for example, between 0 percent inclusive and 30 percent inclusive indium. In the present case it is p-doped with magnesium, for example in a concentration of from 1 × 10 ¹⁹ atoms / cm ³ up to and including 3 × 10 ²⁰ atoms / cm ³ .

In the present case, the intermediate layer 23 is an Al InGaN layer, in particular an AlGaN layer. The aluminum content in the n-type barrier layer 231 and in the p-type barrier layer 233 is, for example, between 20 percent and 100 percent, with the limits included. In the present case, it is 80 percent. The aluminum content in the middle layer 232 is less than the aluminum content in the n-type barrier layer 231 and the aluminum content in the p-type barrier layer 233. In particular, the aluminum content is between 0 percent and 20 percent with the limits included.

In one embodiment, the intermediate layer 23 is nominally undoped. Alternatively, the intermediate layer 23 may also be p-doped. For example, the n-type barrier layer 231 and the p-type barrier layer 233 each have magnesium as the p-type dopant, in particular at a concentration of between 1 × 10 ¹⁹ atoms / cm ³ and 5 × 10 ¹⁹ atoms / cm ³ inclusive. The middle layer 232 is p-doped in one embodiment with magnesium in a concentration between 0 and 2 x 10 ¹⁹ atoms / cm ³ , the boundaries being included. The n-barrier layer 231 and the p-barrier layer 233 have, for example, a layer thickness of less than or equal to 1 nm. The middle layer 232 has, for example, a layer thickness between 1 nm and 8 nm, where the limits are included. In the present case, the n- and p-barrier layers each have an aluminum content of about 80 percent. The percentages in each case relate to the proportion n in the material composition Al _n In _m Gai- _nm N.

FIG. 4 schematically shows the band structure of the optoelectronic semiconductor body according to FIG. The energy E of the band edges of the conduction band L and the valence band V are shown as a function of the position in the semiconductor body x. To assign the x values to the layers of the optoelectronic semiconductor body, these are shown in the upper area of the diagram.

The bandgap of the semiconductor body is increased in the region of the n-barrier layer 231 and the p-barrier layer 233 in comparison to the respectively adjacent layers. Due to the n-type barrier layer 231 and due to the p-type barrier layer 233, strong polarization charges are formed which lead to particularly high carrier density and steep carrier density profiles in the n-type tunnel junction layer 221 and the p-type tunnel junction layer 22.

The charge carrier density D of the electrons DE and the holes DH is also shown schematically in FIG. Due to the high carrier densities DE, DH, a particularly large lateral current spread in the n-type tunnel junction layer 21 and the p-type tunnel junction layer 22 is achieved. In addition, the bandgap in the region of the middle layer 232 is smaller than in the region of the n-type barrier layer 231 and the p-type barrier layer 232 and the distance between the regions of high carrier density DE and DH is comparatively low. The tunnel junction has one in this way especially low electrical resistance. In other words, by means of the barrier layers 231, 233 and the middle layer 232 at the same time a high carrier density and a high tunneling probability can be achieved.

Figure 2 shows a schematic sectional view of an optoelectronic semiconductor body according to a second embodiment. The semiconductor body according to the second embodiment differs from that of the first embodiment in that both the n-type tunnel junction layer 21 and the p-type tunnel junction layer 22 are implemented as superlattices of alternating layers with different material composition and / or dopant concentration , N-type or p-type tunnel junction layers 21, 22 designed as superlattices are suitable for all configurations of the optoelectronic semiconductor body.

For example, the n-type tunnel junction layer 21 and / or the p-type tunnel junction layer 22 are implemented as superlattices of alternating InGaN and GaN layers. The superlattice contains in a further development in the case of the p-type tunnel junction layer 22 highly p-doped InGaN layers and nominally undoped GaN layers.

The layer thickness of the individual layers of the superlattice is preferably 2 nm or less, more preferably 1 nm or less. For example, the layer thickness is 0.5 nm each. The p-type tunnel junction layer 22 and / or the n-type tunnel junction layer 21 preferably has a thickness of 40 nm or less, more preferably 20 nm or less. For example, the superlattice contains between five and fifteen pairs of layers, with the boundaries For example, the superlattice includes 10 pairs of layers.

Advantageously, a tunnel junction layer 21, 22, which is formed as a superlattice, has a particularly good morphology of the crystal structure. In particular, the morphology is improved compared to a highly doped single layer. The multiplicity of interfaces contained in the superlattice structure reduces the risk of propagation of dislocations in the semiconductor body.

FIG. 5A schematically illustrates the band structure of the semiconductor body according to the exemplary embodiment of FIG. The designations in FIG. 5A correspond to those of FIG. 4. FIG. 5B schematically shows the corresponding charge carrier density D of the electrons DE and holes DH.

The formation of the n-type tunnel junction layer 21 and / or p-type tunnel junction layer 22 as a superlattice leads to a further increase in the charge carrier concentration in the tunnel junction layers and thus to an improvement in the current spread compared to corresponding individual layers.

Another difference between the optoelectronic semiconductor body according to the second exemplary embodiment and the optoelectronic semiconductor body according to the first exemplary embodiment is that the intermediate layer 23 is specifically provided with impurities 6. In the present case, the intermediate layer 23 contains no n-barrier layer and no p-barrier layer, as described in connection with the first embodiment. Such n- and p- However, barrier layers are also suitable for the second embodiment.

In the present case, the intermediate layer 23 is provided with the impurities 6 in a middle region 23b, while the region 23a adjoining the n-type tunnel junction layer 21 or the adjacent region 23a and the region 23c adjacent or adjacent to the p-type tunnel junction layer 22 the intermediate layer 23 is not specifically provided with the impurities 6, that is in particular free of the impurities 6.

In the production of the optoelectronic semiconductor body, in particular, the intermediate layer 23 is produced by depositing a semiconductor material, in particular AlInGaN or GaN, in an epitaxy reactor. According to a first embodiment, during the deposition of the middle region 23b, hydrogen gas is conducted into the epitaxy reactor. By means of the hydrogen gas, during the epitaxial deposition of the middle region 23b of the intermediate layer 23, defects are selectively generated in the semiconductor material, which constitute the impurities 6.

For example, the hydrogen gas is passed into the epitaxy reactor at a rate of six standard cubic centimeters per minute. The period of time over which the hydrogen gas is passed into the epitaxy reactor is preferably two minutes or less, more preferably one minute or less.

In an alternative embodiment, the defects 6 are generated by, during the deposition of the central region for a period of, for example, 120 seconds or less the process temperature and / or the pressure in the epitaxial reactor are changed greatly. Under a strong change, for example, a change in pressure by 100 millibars per minute or more or the temperature is understood by 60 Kelvin per minute or more. The change can be gradual or continuous, as so-called temperature or pressure ramp.

As a further alternative, the impurities 6 may also be generated by imparting impurities in addition to the semiconductor material during the epitaxial growth of the central region 23b. The foreign atoms are, for example, at least one metal, at least one transition metal and / or at least one element of the rare earths. The deposition of a combination of several metals, transition metals and / or rare earths is also conceivable. For example, bromine, iron and / or manganese are suitable as foreign atoms.

In contrast to customary p-type dopants or n-type dopants such as magnesium or silicon, such foreign atoms have the advantage that they generate electronic states which are arranged energetically approximately in the middle of the band gap of the intermediate layer 23. This is shown schematically in FIG. 5A. The tunnel current of the tunnel junction 2 advantageously increases disproportionately with the concentration of the foreign atoms 6.

The foreign atoms are present, for example, in a concentration of greater than or equal to 10 ¹⁵ atoms / cm ³ . The concentration is particularly preferably less than or equal to 10 ¹⁹ atoms / cm ³ , since above such a concentration there is a risk of impairing the morphology of the intermediate layer 23 increases. Foreign atoms which are deposited during the epitaxial growth of the semiconductor material are incorporated in particular in the crystal lattice of the semiconductor material. Alternatively, the impurities and the semiconductor material may also be sequentially deposited. This is explained below in connection with the third embodiment.

The deep impurities or "midgap states", which are caused by the foreign atoms 6, advantageously facilitate the charge carriers through the tunneling of the intermediate layer 23. In this way, the efficiency of the tunnel junction 2 is improved compared to a tunnel junction without deliberately introduced impurities.

FIG. 3 shows a schematic cross section through an optoelectronic semiconductor body according to a third exemplary embodiment. The optoelectronic semiconductor body according to the third embodiment corresponds to that of the first embodiment. In addition, however, the middle layer 232 of the intermediate layer 23 is specifically provided with impurities 6, as described in connection with the second embodiment. In the present case, the impurities 6 are foreign atoms which are introduced as a layer into the middle layer 232.

In the production of the semiconductor body, a first part 2321 of the middle layer 232 is first deposited on the n-barrier layer 231, in contrast to the production method described in connection with the second embodiment. Subsequently, the layer of impurities 6 is deposited. Finally, a second part of the intermediate layer 2322 on the impurities 6 and the first Part 2321 deposited. Subsequently, the intermediate layer 23 is completed by depositing the p-barrier layer 233.

The layer of foreign atoms 6 is produced in such a way that it has openings. In other words, the first part 2321 of the middle layer 232 is locally covered by the impurity atoms 6 and partially uncovered by the impurity atoms 6. The second part 2322 of the middle layer 232 is then deposited in such a way that it adjoins the latter in the region of the openings of the layer of foreign atoms 6, ie where the first part 2321 of foreign atoms 6 is uncovered. The layer thickness of the layer of foreign atoms 6 is expediently chosen so that the layer of impurity atoms 6 can be epitaxially overgrown. In one embodiment, the layer of foreign atoms 6 is a non-closed monolayer. However, larger layer thicknesses are also conceivable. For example, the layer of impurities 6 has a layer thickness between 0.1 nm and 10 nm, preferably between 0.1 nm and 3 nm, the boundaries being included.

In the present embodiment, the center region 23b provided with impurities 6 of the intermediate layer 23 corresponds to the layer of foreign atoms 6. The barrier layers 231, 233 and in the present case also partial regions of the middle layer 232 which precede or follow the middle region 23b are free of the foreign atoms. For the production of the impurity 6 provided with the central region 23b of the intermediate layer 23 and the manufacturing method mentioned in connection with the second embodiment are also suitable. Conversely, a layer of impurities 6 and the manufacturing process, as in Related to the present embodiment are also suitable for the second embodiment.

The invention is not limited by the description based on the embodiments of these. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims and exemplary embodiments, even if this feature or this combination itself is not explicitly stated in the patent claims or exemplary embodiments.

Claims

claims

1. An optoelectronic semiconductor body with an epitaxial semiconductor layer sequence, which has a tunnel junction (2) and provided for emission of electromagnetic radiation active layer (4), wherein the tunnel junction, an intermediate layer (23) between an n-type tunnel junction layer (21) and a p Type tunnel junction layer (22) and the intermediate layer has an n-type tunnel junction layer facing n-type barrier layer (231), a p-type tunnel junction layer facing p-type barrier layer

(233) and a middle layer (232) whose material composition differs from the

Material composition of the n-barrier layer and the p-barrier layer is different.

2. An optoelectronic semiconductor body according to claim 1, wherein the n-barrier layer (231), the middle layer

(232) and the p-barrier layer (233) comprise a semiconductor material containing a first and a second component and the proportion of the first component in the middle layer is smaller than in the n-barrier layer and the p-barrier layer.

3. The optoelectronic semiconductor body according to claim 2, wherein the first component contains or consists of aluminum and the second component contains at least one element selected from the group consisting of In, Ga, N, and P.

4. The optoelectronic semiconductor body according to claim 2, wherein the proportion of the first component in the middle layer (232) is less than or equal to 20% and greater in the n-barrier layer (231) and the p-barrier layer (233) is equal to 20%.

5. Optoelectronic semiconductor body according to one of the preceding claims, wherein a layer thickness of the n-barrier layer (231) and / or the p-barrier layer

(233) is less than or equal to 2 nm.

6. An optoelectronic semiconductor body with an epitaxial semiconductor layer sequence comprising a tunnel junction (2) and an active layer provided for the emission of electromagnetic radiation

(4), wherein the tunnel junction has an intermediate layer (23) between an n-type tunnel junction layer (21) and a p-type tunnel junction layer (22), and the intermediate layer is specifically provided with impurities (6).

7. Optoelectronic semiconductor body according to one of claims 1 to 5, wherein the intermediate layer (23) in the region of the middle layer (232) targeted with impurities

(6) is provided.

8. Optoelectronic semiconductor body according to one of claims 6 or 7, wherein the impurity (6) are at least partially formed by defects of a semiconductor material of the intermediate layer (23).

9. Optoelectronic semiconductor body according to one of claims 6 to 8, wherein the impurity (6) are at least partially formed of foreign atoms, which are incorporated in the crystal lattice of a semiconductor material of the intermediate layer (23) and / or in which the foreign atoms (6) as Layer in the intermediate layer (23) are included.

10. An optoelectronic semiconductor body according to any one of claims 6 to 8, wherein the impurities (6) are at least partially formed of foreign atoms, which are contained as a layer in the intermediate layer and the layer of foreign atoms (23 b) has openings which passes through the semiconductor material are.

11. An optoelectronic semiconductor body according to one of the preceding claims, wherein the n-type tunnel junction layer (21) and / or the p-type tunnel junction layer (22) is designed as a superlattice of alternating layers.

12. A method for producing an optoelectronic semiconductor body with an epitaxial semiconductor layer sequence which has a tunnel junction (2) and an active layer (4) provided for emission of electromagnetic radiation, the tunnel junction comprising an n-type tunnel junction layer (21), an intermediate layer (23 ) and a p-type tunnel junction layer (22), in which for the production of the intermediate layer, a semiconductor material is epitaxially deposited and at least selectively provided with impurities (6).

13. A method according to claim 12, wherein the impurity imparting comprises introducing defects into the semiconductor material, at least temporarily passing hydrogen gas into the epitaxial reactor during introduction of the defects during deposition of the semiconductor material in an epitaxial reactor.

14. The method of claim 12, wherein the impurity (6) comprises introducing defects into the semiconductor material, wherein during deposition of the semiconductor material in one Epitaxy reactor for introducing the defects (6) a process temperature and / or a pressure in the epitaxy is changed.

A method according to claim 12, wherein the impurity imparting (6) comprises introducing impurities into the intermediate layer (23).