Wafer, light emitting device, method for producing wafer, and method for characterizing system for producing wafer

Abstract

The present application relates to a wafer (10), comprising: a substrate (11); at least one intermediate layer, the at least one intermediate layer being formed on the surface of the substrate (11), wherein the at least one intermediate layer at least partially covers the surface of the substrate (11), and wherein an outer surface (15) of the at least one intermediate layer points toward a surface (11a) facing away from the substrate (11); and a nanostructure (16), the nanostructure being grown on the outer surface (15) of the at least one intermediate layer, wherein the at least one intermediate layer is formed in such a way that a growth position (15a) of the nanostructure (16) is predetermined on the outer surface (15) of the at least one intermediate layer, and wherein at least one nanostructure material of the nanostructure (16) is assembled at the growth position (15a) of the nanostructure (16).

Description

Technical Field

[0001] The present invention relates to a wafer and a light emitting device. The present invention also relates to a method of producing a wafer and a method of characterizing a system for producing a wafer. Background Art

[0002] CN104538524A describes a growth method for growing an epitaxial structure containing InGaN quantum dots on a substrate, which method requires a step surface of the substrate with a chamfer of 0.05 to 0.1 to form InGaN quantum dots at a position close to the step surface of the substrate.

[0003] It is an object of the invention to provide an improved wafer, an improved growth method and / or an improved method of characterizing a system for producing wafers. Summary of the invention

[0004] The above mentioned objects are solved by a wafer having the features of claim 1, a wafer having the features of claim 2, a light emitting device having the features of claim 8, a method for producing a wafer having the features of claim 9, a method for producing a wafer having the features of claim 11 and a method characterizing a system for producing a wafer having the features of claim 16. Accordingly, the following is provided:

[0005] - A wafer, comprising: a substrate; at least one intermediate layer, the at least one intermediate layer being formed on a surface of the substrate, wherein the at least one intermediate layer at least partially covers the surface of the substrate, and wherein an outer surface of the at least one intermediate layer is directed toward a surface away from the substrate; and a nanostructure, the nanostructure being grown on the outer surface of the at least one intermediate layer, wherein the at least one intermediate layer is formed in such a way that a growth position of the nanostructure is predetermined on the outer surface of the at least one intermediate layer, and wherein at least one nanostructure material of the nanostructure is assembled at the growth position of the nanostructure.

[0006] - A wafer, comprising: a substrate; at least one intermediate layer, which is formed on a surface of the substrate, wherein the at least one intermediate layer at least partially covers the surface of the substrate, and wherein an outer surface of the at least one intermediate layer points to a surface facing away from the substrate; and a wetting layer, which at least partially covers an outer surface of the at least one intermediate layer, wherein the at least one intermediate layer is formed in such a way that a modified position of a modified subregion of the wetting layer is predetermined on the outer surface of the at least one intermediate layer, and wherein the modified subregion of the wetting layer covering the modified position has a different wetting layer thickness and / or a different wetting layer composition than a remaining subregion of the wetting layer covering the outer surface of the at least one intermediate layer around the modified position, so that the light emission characteristics and / or electron transport characteristics of the modified subregion of the wetting layer are different from those of the remaining subregion of the wetting layer.

[0007] - A method for producing a wafer, comprising the following steps:

[0008] At least one intermediate layer is formed on a surface of the substrate, wherein the surface of the substrate is at least partially covered by the at least one intermediate layer, and wherein an outer surface of the at least one intermediate layer is formed pointing away from the surface of the substrate, and

[0009] A nanostructure is grown on the outer surface of at least one intermediate layer, wherein the at least one intermediate layer is formed in such a way that a growth position of the nanostructure is predetermined on the outer surface of the at least one intermediate layer, and wherein the nanostructure is grown on the outer surface of the at least one intermediate layer by depositing at least one nanostructure material of a subsequent nanostructure on the outer surface of the at least one intermediate layer in such a way that the at least one nanostructure material is assembled at the growth position of the nanostructure.

[0010] - A method for producing a wafer, comprising the following steps:

[0011] At least one intermediate layer is formed on the surface of a substrate, wherein the surface of the substrate is at least partially covered by the at least one intermediate layer, and wherein an outer surface of the at least one intermediate layer is formed that points away from the surface of the substrate; and a wetting layer is formed that at least partially covers the outer surface of the at least one intermediate layer, wherein the at least one intermediate layer is formed in such a way that a modification position of a modified subregion of the wetting layer is predetermined on the outer surface of the at least one intermediate layer, and wherein the modified subregion of the wetting layer covering the modified position is formed with a different wetting layer thickness and / or a different wetting layer composition than a remaining subregion of the wetting layer covering the outer surface of the at least one intermediate layer around the modified position, so that the light emission characteristics and / or electron transport characteristics of the modified subregion of the wetting layer are changed compared to the remaining subregion of the wetting layer.

[0012] The present invention is based on the concept of forming at least one intermediate layer in such a way that the growth position of the nanostructure or the modified position of the modified sub-region of the wetting layer is determined / generated. Therefore, using the present invention, it is not necessary to have a substrate with a stepped surface for growing the nanostructure or modifying the modified sub-region of the wetting layer. In contrast to the prior art mentioned above, the present invention can be performed using a substrate with a flat surface (e.g. without miscuts). Therefore, it is possible to have a chamfered form or a uniform average wafer height. Therefore, the present invention reduces the cost of wafers for growing modified sub-regions of nanostructures and / or their wetting layers. In addition, compared to the prior art, the present invention reduces the requirements for the substrate of the wafer for growing the modified sub-region of the nanostructure or its wetting layer.

[0013] Furthermore, the invention also enables the nanostructures of the wafer to be arranged arbitrarily and independently of the surface of the substrate on which the nanostructures are grown. Thus, the invention provides a wafer with an arbitrary distribution of its nanostructures, with a preferred "pattern" of its nanostructures. Accordingly, the invention also provides a wafer with an arbitrary distribution of modified sub-areas of its wetting layer, or with a preferred "pattern" of modified sub-areas of its wetting layer.

[0014] In a particularly preferred embodiment of the wafer, at least one intermediate layer is formed in such a way that compositional or morphological inhomogeneities are formed on the outer surface of at least one intermediate layer as growth locations of nanostructures or as modified locations of the changed sub-regions of the wetting layer. These compositional or morphological inhomogeneities provide reliable pre-determination of the growth locations of the nanostructures or the modified locations of the changed sub-regions of the wetting layer. Therefore, the compositional inhomogeneities of the growth locations may be associated with changes in chemical compounds (such as atomic elements and molecules). The application of the same or different materials may also result in morphological inhomogeneities, which may be associated with local changes in, for example, the crystal structure. Such modification generally results in a local reduction in the critical minimum thickness at the growth location or the modified location, which increases the possibility of nanostructure formation or modification of the changed sub-region of the wetting layer.

[0015] In a preferred embodiment of the wafer, at least one intermediate layer comprises a stack of at least two layers, wherein at least two layers of the stack each have a varying layer thickness perpendicular to the surface of the substrate, and wherein the thickness of the stack perpendicular to the surface of the substrate is constant. This embodiment of the wafer typically has a flat outer surface of its stack pointing away from its substrate surface. The flat outer surface can have areas of different roughness. The different roughness of the flat outer surface can be used for the growth position of a predetermined nanostructure or the modification position of a changed sub-area of ​​a wetting layer.

[0016] In another preferred embodiment of the wafer, at least one intermediate layer comprises a layer with a periodically or arbitrarily varying layer thickness perpendicular to the surface of the substrate. The determination of the growth position of the nanostructures or the modified position of the modified subregion can thus be caused by the change in the outer surface roughness caused by the periodically or arbitrarily varying layer thickness of the at least one intermediate layer. The periodically or arbitrarily varying layer thickness of the at least one intermediate layer represents a simple way of determining the growth position of the nanostructures and / or the modified position of the modified subregion of the wetting layer.

[0017] In a preferred embodiment of the wafer, the nanostructure comprises nano-islands, droplets, nano-lines, nano-rings, nano-pillars, nano-wires, nano-belts, nano-rods, nano-piles, quantum dots, biological cells and / or biomolecules. Since the process applied is not limited to any special form of nanostructure, other nanostructures are also conceivable. Moreover, biological cells (e.g., bacterial cells) and biomolecules (e.g., viruses, antibodies, DNA chains or RNA chains) may also be applied to this process. In this way, the present invention provides a standard recipe for lateral arrangement of such nanostructures. Since the growth position and the modified position may have hydrophobic or hydrophilic properties, the water droplets containing biological cells and / or biomolecules may be accumulated on the growth position and the modified position of the changed sub-region.

[0018] In a preferred embodiment, the wafer comprises: at least a first intermediate layer as at least one intermediate layer thereof; a first plurality of nanostructures; at least a second intermediate layer, the at least second intermediate layer covering the first plurality of nanostructures; and a second plurality of nanostructures, the second plurality of nanostructures grown on an outer surface of the at least one second intermediate layer. Moreover, at least one or more nanostructures may be grown on the second plurality of nanostructures, wherein at least one additional intermediate layer is arranged between the at least one or more nanostructures and at least one adjacent plurality of nanostructures thereof.

[0019] In an advantageous embodiment of the wafer, for each of the first plurality of nanostructures, one of the second plurality of nanostructures is arranged in a direction perpendicular to the surface of the substrate. This advantageous embodiment thus represents an example of a three-dimensional structure of a repeating "pattern" of nanostructures. Such an embodiment of the wafer can be used as a quantum repeater. However, the first plurality of nanostructures and the second plurality of nanostructures can also have a different spatial distribution.

[0020] The above-mentioned advantages can also be used for light emitting devices having such a chip, wherein the light emitting device is a laser, an LED, a super radiant LED or a single photon source. For example, a laser locked with a desired spatial mode and a desired wavelength can be produced using such a chip. An LED or a super radiant LED with a desired spectral distribution can also include such a chip. In addition, a single photon source emitting with a desired emission frequency and a desired wavelength can also include such a chip. Such a light emitting device has great applicability in scientific and industrial processes, life science applications and / or optical communication networks or quantum communication networks.

[0021] In a preferred embodiment of the method for producing a wafer, a nanostructure is grown on the outer surface of at least one intermediate layer by depositing at least one nanostructured material of a subsequent nanostructure on the outer surface of at least one intermediate layer in such a manner that the nanostructure is formed by self-aggregation, self-assembly, crystallization and / or nucleation of at least one nanostructured material assembled at the growth position of the nanostructure. Therefore, the formation process of the nanostructure does not require any "controlled" deposition of materials. On the contrary, certain physical effects (such as self-aggregation, self-assembly, crystallization and / or nucleation) can be used for the self-formation of the nanostructure while performing a simple deposition step. The nanostructure can be grown by, for example, Stranski-Krastanov type growth (layer-island growth). Although statistical in nature, due to the predetermination of the growth position, the nanostructure is "automatically" formed at a predetermined position while performing a simple deposition step.

[0022] In a preferred embodiment of the method for producing a wafer, at least one intermediate layer is formed in such a way that compositional or morphological inhomogeneities are formed on the outer surface of the at least one intermediate layer as growth sites of nanostructures or as modification sites of altered sub-regions of the wetting layer. As will be explained below, the compositional or morphological inhomogeneities can be formed by easily performed process steps.

[0023] For example, forming at least one intermediate layer with compositional or morphological inhomogeneities on the outer surface of at least one intermediate layer comprises the following steps: forming a layer with a periodic or arbitrarily varying layer thickness perpendicular to the surface of the substrate by depositing at least one material of the layer with a periodic or arbitrarily varying layer thickness on the surface of the substrate or on another intermediate layer through the openings of a shielding mask. For example, the use of a shielding mask for the intermediate layer enables the formation of a spatial periodicity or an arbitrary thickness variation of the intermediate layer. In addition, the location of the material deposition and its spacing can be controlled in a direct manner. Thus, the versatility of the distribution of the subsequently formed nanostructure distribution or the modification of the modified sub-regions of the subsequently formed wetting layer can be further increased.

[0024] In another preferred embodiment of the method for producing a wafer, forming at least one intermediate layer having a compositional or morphological inhomogeneity on an outer surface of at least one intermediate layer comprises the following steps: forming a layer having a periodically or arbitrarily varying layer thickness perpendicular to the substrate surface by depositing at least one material of the layer having a periodically or arbitrarily varying layer thickness, wherein during the deposition of at least one material of the layer having a periodically or arbitrarily varying layer thickness, the position of the shutter device relative to the substrate is changed stepwise or continuously from an initial position of the shutter device to an end position of the shutter device, and wherein a first amount of a material flow of at least one deposited material of the layer having a periodically or arbitrarily varying layer thickness blocked by the shutter device at its initial position is different from a second amount of a material flow of at least one deposited material of the layer having a periodically or arbitrarily varying layer thickness blocked by the shutter device at its end position. The first amount of a material flow blocked by the shutter device at its initial position may be greater than or less than the second amount of a material flow blocked by the shutter device at its end position. Using a shutter device to block the material flow is a simple and inexpensive method for forming an intermediate layer having a periodically or arbitrarily varying thickness perpendicular to the surface of the substrate. The shutter device may be a conventional shutter or any other suitable device that can at least partially block the molecular flow from a material source, such as an effusion unit. For example, periodic or randomly varying thickness variations, such as a "sawtooth" structure, can be easily formed in this way. In addition, during the process, the position or angle of the wafer can be varied to form an inhomogeneous portion in the intermediate layer with a periodic or randomly varying layer thickness in two dimensions. For example, in order to form a two-dimensional array / grid / lattice structure, rotation of the wafer can be applied during the process.

[0025] Furthermore, a layer having a periodically or randomly varying layer thickness may be covered by the second intermediate layer to form a compositional or morphological inhomogeneity of the second intermediate layer.Therefore, a compositional or morphological inhomogeneity may be provided on a flat outer surface of the second intermediate layer.

[0026] The method of the present invention for characterizing a system for producing wafers comprises the following steps: producing a wafer using the above-mentioned embodiment of the method for producing a wafer, wherein at least one intermediate layer of the wafer and / or at least one material of the nanostructure of the wafer is deposited by at least one material source of the system; and performing at least one measurement of the nanostructure of the produced wafer to determine the flow density distribution of at least one material source of the system.

[0027] In a preferred embodiment of the method for characterizing a system for producing wafers, the layer thickness distribution of at least one intermediate layer is studied by at least one measurement, and the flow density distribution of at least one material source of the system is determined based on the detected layer thickness distribution of the at least one intermediate layer. Since a material source (such as an effusion unit) usually emits material with an inhomogeneous flow density (e.g. radial emission inhomogeneities and / or inhomogeneous flow density caused by the angle of the material source relative to the substrate), the layer deposited by such a material source has a layer thickness that varies according to the flow density variation. By the subsequent formation of the nanostructures, the layer thickness can be determined. Therefore, the layer thickness provides information about the flow of the material source. Knowing the flow density of the material source helps to produce perfectly flat layers or, if desired, to produce layers with arbitrary thickness profiles from scratches.

[0028] In another preferred embodiment of the method of characterizing a system for producing a wafer, the wafer is formed with at least a first intermediate layer as at least one intermediate layer thereof, a first plurality of nanostructures having a first physical and / or chemical property as nanostructures thereof, at least a second intermediate layer covering the first plurality of nanostructures and a second plurality of nanostructures having a second physical and / or chemical property different from the first physical and / or chemical property grown on the outer surface of at least one second intermediate layer, wherein at least a first material source of the system is used to deposit the first intermediate layer, and at least a second material source is used to deposit the second intermediate layer, and wherein at least one measurement comprises a first measurement of the first plurality of nanostructures to determine the flow density distribution of the first material source, and a second measurement of the second plurality of nanostructures to determine the flow density distribution of the second material source. In such a way, the characterization of different material sources can be performed very efficiently on the same wafer with subsequent measurements. The physical property of the nanostructures can be the size, volume, shape, crystal structure, temperature or any other physical property parallel or perpendicular to the surface of the substrate. The chemical property of the nanostructures can be the composition of the applied material, alloy or isotope, their molecular structure or any other chemical property. The measurement can be performed by, but not limited to, photoluminescence measurement. Moreover, the first measurement and the second measurement can be performed simultaneously. In case at least one third measurement is also performed, the at least one third measurement may be formed simultaneously with the first measurement and / or the second measurement.

[0029] Where appropriate, the configurations and developments mentioned above may be combined in any manner. Other possible configurations, developments and embodiments of the present invention also include combinations of features of the present invention that have been described above or described below with reference to the embodiments that have not been explicitly mentioned. In particular, in this case, those skilled in the art will also add various aspects as improvements or supplements to the basic form of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention is described in more detail below based on an embodiment shown in the schematic diagram of the accompanying drawings, in which:

[0031] Figures 1A to 1F shows a cross section for illustrating the layer composition of a first embodiment of a method for producing a wafer;

[0032] FIG. 2A to FIG. 2D A cross section and a top view of another layer composition for illustrating a second embodiment of a method for producing a wafer are shown;

[0033] FIG. 3A to FIG. 3D A cross section and a top view are shown for illustrating another layer composition of a third embodiment of a method for producing a wafer;

[0034] 4A to 4D shows a cross section for illustrating the layer composition of a fourth embodiment of a method for producing a wafer;

[0035] FIG. 5A to FIG. 5D shows a cross section for illustrating the layer composition of a fifth embodiment of a method for producing a wafer;

[0036] FIG. 6A to FIG. 6B shows a cross section for illustrating the layer composition of a sixth embodiment of a method for producing a wafer;

[0037] Figure 7 An embodiment during light emission is shown;

[0038] Fig. 8A and Figure 8B A schematic diagram and simulation results for illustrating another embodiment of a method of characterizing a system for producing wafers are shown; and

[0039] Fig. 9 A wafer is shown which can be used to perform the method described above.

[0040] The accompanying drawings are intended to provide a further understanding of the embodiments of the present invention. They illustrate embodiments and, in conjunction with the description, help explain the principles and concepts of the present invention. In view of the accompanying drawings, other embodiments and many advantages mentioned will become apparent. The elements in the drawings are not necessarily shown to scale.

[0041] In the figures, similar, functionally equivalent and identical operating elements, features and components are provided in each case with similar reference symbols, unless otherwise indicated. DETAILED DESCRIPTION

[0042] Figures 1A to 1F A cross section is shown for illustrating the layer composition of a first exemplary embodiment of a method for producing a wafer 10 .

[0043] like Figure 1AAs shown, a substrate 11 is provided. By performing the method for producing the wafer 10, the surface 11a of the substrate 11 is at least partially covered by at least one intermediate layer 12 to 14. Preferably, the surface 11a of the substrate 11 on which the at least one intermediate layer 12 to 14 is grown is a flat surface 11a. Therefore, preferably, the thickness of the substrate 11 perpendicular to the surface 11a is constant. Another surface 11b of the substrate 11 pointing away from the surface 11a, on which the at least one intermediate layer 12 to 14 is grown, may also be flat. In addition, the substrate 11 may be formed of a variety of different materials, for example at least one semiconductor material, such as silicon and / or gallium arsenide. Therefore, a variety of different types of substrates may be used as the substrate 11. Therefore, the method for producing the wafer 10 can be performed by using a relatively "cheap" substrate 11.

[0044] The method of producing the wafer 10 may be implemented by using a "smaller" or "larger" substrate 11. Exemplarily, the diameter of the substrate 11 may be at least 50 mm, such as at least 75 mm, or even at least 100 mm.

[0045] like Figure 1B As shown, the basic intermediate layer 12 is formed on the surface 11a of the substrate 11. Exemplarily, the basic intermediate layer 12 is formed to have a varying layer thickness perpendicular to the surface 11a of the substrate 11. Figure 1B In the example of , the layer thickness of the base intermediate layer 12 perpendicular to the surface 11a of the substrate 11 increases constantly from the first side 11c of the substrate 11 to the second side 11d of the substrate 11 pointing away from the first side 11c. Then, the covering intermediate layer 13 may be formed on the surface of the base intermediate layer 12 pointing away from the surface 11a of the substrate 11. The covering intermediate layer 13 may have a constant or varying layer thickness perpendicular to the surface 11a of the substrate 11.

[0046] like Figure 1C As shown, an outer intermediate layer 14 is then formed on the surface of the cover intermediate layer 13 that points away from the surface 11a of the substrate 11. Preferably, the outer intermediate layer 14 is formed with a varying layer thickness perpendicular to the surface 11a of the substrate 11. Figure 1C In the example of , the layer thickness of the outer intermediate layer 14 perpendicular to the surface 11a of the substrate 11 increases constantly from the second side 11d of the substrate 11 to the first side 11c of the substrate 11. Thus, a stack of intermediate layers 12 to 14 is formed, wherein the thickness of the stack perpendicular to the surface 11a of the substrate 11 is (usually) constant. However, the outer surface 15 of the intermediate layers 12 to 14 pointing away from the surface 11a of the substrate 11 is formed with a varying roughness, wherein a region 15a of the outer surface 15 has a higher roughness and a region 15b of the outer surface 15 has a lower roughness.

[0047] Thus, the flat outer surface 15 of the outer intermediate layer 14 has regions 15a and 15b of different surface roughness. The different surface roughness of the flat outer surface 15 of the outer intermediate layer 14 may be caused by different step densities of the atomic monolayer.

[0048] Figure 1D An example of a portion of such an outer intermediate layer 14 is shown, comprising a region 15a of the outer surface 15 having a higher roughness (or "rough" surface) and a remaining region 15b having a lower roughness (or "smooth" surface). Figure 1E Another example of a portion of such an outer mid layer 14 is shown. Figure 1E Indicates unavoidable / intentional wafer miscutting situations.

[0049] like Figure 1F As shown, nanostructures 16 are then grown on the outer surface 15 of at least one of the intermediate layers 12 to 14. Figure 1F It can be seen that at least one intermediate layer 12 to 14 is formed in such a way that the growth positions 15a of the nanostructure 16 (e.g. the regions 15a of the outer surface 15 with higher roughness) are predetermined on the outer surface 15 of the at least one intermediate layer 12 to 14. The nanostructure 16 grows on the outer surface 15 of the at least one intermediate layer 12 to 14 by simply depositing at least one nanostructure material of the latter nanostructure 16 on the outer surface 15 of the at least one intermediate layer 12 to 14 in such a way that the at least one nanostructure material is assembled at the growth positions 15a of the nanostructure 16. Preferably, the nanostructure 16 grows on the outer surface 15 of the at least one intermediate layer 12 to 14 by depositing at least one nanostructure material in such a way that the nanostructure 16 is formed by self-aggregation, self-assembly, crystallization and / or nucleation of at least one nanostructure material assembled at the growth positions 15a of the nanostructure 16. The nanostructure can be grown by, for example, Stranski-Krastanov type growth (layer-island growth). Figure 1E and 1F The comparison of and in particular emphasizes that roughness (compositional or morphological inhomogeneities) is the driving factor for aligning the nanostructures 16. Thus, Figure 1F. The wafer 10 is shown in FIG. The wafer 10 includes a substrate 11, at least one intermediate layer 12 to 14 formed on a surface 11a of the substrate 11, wherein the at least one intermediate layer 12 to 14 at least partially covers the surface 11a of the substrate 11. An outer surface 15 of the at least one intermediate layer 12 to 14 pointing away from the surface 11a of the substrate 11 has a nanostructure 16 grown on the outer surface 15. As explained above, the at least one intermediate layer 12 to 14 is formed in such a way that a growth position 15a of the nanostructure 16 is predetermined on the outer surface 15 of the at least one intermediate layer 12 to 14, wherein at least one nanostructure material of the nanostructure 16 is assembled at the growth position 15a of the nanostructure 16. Therefore, the wafer 10 can be produced by carrying out process steps that can be easily carried out. Therefore, the wafer 10 can have a chamfered form (by omitting Figure 1B method steps) or a uniform average height.

[0050] At least one of the intermediate layers 12 to 14 may be formed by a molecular beam epitaxy (MBE) process. At least one material of at least one of the intermediate layers 12 to 14 may be formed by, for example, a material source of an effusion unit (in Figures 1A to 1F As at least one material of at least one intermediate layer 12 to 14, gallium arsenide is preferably applied, but other materials and compositions are also applicable, such as indium gallium arsenide, aluminum gallium arsenide, indium arsenide or any other suitable III-V group composition or other composition of semiconductors (such as silicon and germanium).

[0051] FIG. 2A to FIG. 2D A cross section and a top view are shown for illustrating a further layer composition of a second exemplary embodiment of a method for producing a wafer 20 .

[0052] In this embodiment, the molecular beam 23 of the material source 24 is modulated by the shutter device 25 to form the basic intermediate layer 21 including the inhomogeneous portion 22. Figure 2A In the embodiment shown in FIG. 2 , the shutter device 25 is positioned in such a way that it partially blocks the molecular beam 23. This results in a modulated thickness of the elementary intermediate layer 21 comprising the inhomogeneities 22. The inhomogeneities 22 may be any kind of compositional or morphological inhomogeneities.

[0053] Figure 2Ba The shutter device 25 is shown in its final position. Exemplarily, the final position of the shutter device 25 is an “open” position, wherein the molecular beam 23 is not blocked by the shutter device 25 arranged in its “open” position. For example, a sawtooth-shaped thickness profile of the basic intermediate layer 21 is formed. However, any other periodically or randomly varying layer thickness profile of the basic intermediate layer 21 is also applicable. Figure 2BbIn the top view of FIG. 2 , the linear spatial extension of the uneven portion 22 caused by the modulation using the shutter device 25 is shown.

[0054] like Figure 2C As shown, a covering intermediate layer 26 is then formed on the basic intermediate layer 21. The covering intermediate layer 26 is formed with a plurality of growth locations 27 that are directly "above" the locations of the inhomogeneities 22. "Above" means perpendicular to the surface 11a of the substrate 11 and pointing away from the substrate 11. As will become apparent below, the method of producing a wafer does not require the formation of the covering intermediate layer 26. Alternatively, in some embodiments, the inhomogeneities 22 may also serve as the growth locations 27.

[0055] exist Figure 2D In the next step shown in FIG. 2 , a plurality of nanostructures 28 are formed, for example as quantum dots 28. The nanostructures 28 are preferably formed by another MBE process in which the same or another material is deposited onto the outer surface of the overlying intermediate layer 26. A plurality of nanostructures / quantum dots 28 are formed on the growth sites 27. The nanostructures / quantum dots 28 may be grown on the growth sites 27 by, for example, nucleation, self-aggregation or crystal growth.

[0056] Due to the nature of the inhomogeneities 22 in the thickness profile of the base intermediate layer 21, the statistical uncertainty of the growth position 27 is small / negligible. Hence, a reliable placement of the nanostructures / quantum dots 28 independent of the form of the surface 11a of the substrate 11 is possible.

[0057] FIG. 2A to FIG. 2D The additional characteristics of the method steps of the method and the additional features of the wafer 20 produced by the method are described above with reference to Figures 1A to 1F The embodiments are described.

[0058] FIG. 3A to FIG. 3D A cross section and a top view of a further layer composition for illustrating a third exemplary embodiment of a method for producing a wafer 30 are shown.

[0059] Figure 3A , Figure 3Ba and Figure 3Bb The basic intermediate layer 21 is shown produced on the outer surface of the substrate 11 by means of a modulated molecular beam 23. This process is based on Figure 2A and Figure 2B.

[0060] exist Figure 3C In the production steps shown in Figure 3Ba Compared to the arrangement during the method steps shown in , the wafer 30 is rotated by 90° while a similar material deposition is applied. As a result, a two-dimensional grating-like structure of the inhomogeneities 22 is achieved.

[0061] like Figure 3D As shown, quantum dots 28 are grown on top of the inhomogeneities 22, which act similarly to Figure 2C Of course, the uneven portion 22 may also be covered with a covering intermediate layer 26 to provide the growth position 27 on the outer surface of the covering intermediate layer 26.

[0062] FIG. 3A to FIG. 3D Further characteristics of the method steps of the method and additional features of the wafer 30 produced by the method are described above with reference to the previous embodiments.

[0063] 4A to 4D A cross section is shown for illustrating the layer composition of a fourth exemplary embodiment of a method for producing a wafer 40 .

[0064] Figure 4A A substrate 11 is shown, on which a shadow mask 41 having openings 42 is arranged. Thus, a first material deposition is performed, wherein a material 43 is deposited at the locations of the surface 11a of the substrate 11 determined by the openings 42 of the shadow mask 42. Figure 4B Wafer 40 is shown after a first deposition of material.

[0065] Figure 4C The wafer 40 is shown after the (optional) deposition of additional material for forming an elementary intermediate layer 44. The elementary intermediate layer 44 is formed with inhomogeneities 45 on its outer surface at locations determined by the deposited material 43. Thus, any distribution or pattern of inhomogeneities 45 on the outer surface of the elementary intermediate layer 44 can be selected simply by selecting a suitable shadow mask 41. The inhomogeneities 45 determine the growth locations 45 of the subsequently formed nanostructures 28.

[0066] exist Figure 4D , a wafer 40 is shown after a plurality of nanostructures 28 have been grown, for example as quantum dots 28. The nanostructures / quantum dots 28 are grown on inhomogeneities / growth locations 45 of a base intermediate layer 44. As an alternative to a plurality of quantum dots 28, other nanostructures 28 may be grown using the same process.

[0067] However, it is also possible to omit the essential intermediate layer 44. In this case, the nanostructures / quantum dots 28 are grown directly on the material 43 deposited at the location of the surface 11a of the substrate 11.

[0068] 4A to 4D Further characteristics of the method steps of the method and additional features of the wafer 40 produced by the method are described above with reference to the previous embodiments.

[0069] FIG. 5A to FIG. 5DA cross section is shown for illustrating the layer composition of a fifth exemplary embodiment of a method for producing a wafer 50 . Figure 5A and Figure 5B The production steps are based on Figures 2A to 2D Alternatively, it is also possible to implement Figure 3C production steps.

[0070] exist Figure 5C In the process, a second covering intermediate layer 51 is applied, which has uneven portions 52 on its outer surface and the like to serve as growth locations 52. In an embodiment, the thickness of the second covering intermediate layer 51 is less than 30 nm, preferably less than 15 nm, and in particular less than 10 nm. Therefore, the second covering intermediate layer 51 is (automatically) formed with favorable uneven portions 52 as growth locations 52. Then, a second plurality of quantum dots 53 are grown on the uneven portions / growth locations 52 on the outer surface of the second covering intermediate layer 51. Therefore, the second plurality of quantum dots 51 are grown at a position directly above the first plurality of quantum dots 28 (i.e., perpendicular to the outer surface of the substrate 11). This preferred arrangement is particularly useful for use as a quantum repeater.

[0071] FIG. 5A to FIG. 5D Further characteristics of the method steps of the method and additional features of the wafer 50 produced by the method are described with reference to the above embodiments.

[0072] The method described above can also be implemented to produce a wafer having a wetting layer, which at least partially covers the outer surface of at least one intermediate layer of the wafer, wherein the at least one intermediate layer is formed in such a way that the modification position of the changed subregion of the wetting layer is predetermined on the outer surface of the at least one intermediate layer, and wherein the changed subregion of the wetting layer covering the modification position is formed with a different wetting layer thickness and / or a different wetting layer composition than the remaining subregion of the wetting layer covering the outer surface of the at least one intermediate layer around the modification position, so that the light emission characteristics and / or electron transport characteristics of the changed subregion of the wetting layer are changed compared to the remaining subregion of the wetting layer.

[0073] Fig. 6A and Figure 6B Another layer composition for illustrating a sixth embodiment of a method for producing a wafer is shown.

[0074] First, execute Figures 1A to 1C The method steps are schematically shown in FIG. Fig. 6A Thus, the flat outer surface 15 of the outer intermediate layer 14 has, for example, regions 15a and 15b of different surface roughness.

[0075] Then, if Figure 6BAs shown, the wetting layer 61 is formed on the outer surface 15 of at least one intermediate layer 12, 13 and 14. Since at least one intermediate layer 12, 13 and 14 is formed in such a manner that the modified position 15a of the modified sub-region 61a of the wetting layer 61 is predetermined on the outer surface 15, the modified sub-region 61a of the wetting layer 61 covering the modified position 15a is formed with a wetting layer thickness different from that of the remaining sub-region 61b of the wetting layer 61 covering the outer surface 15 around the modified position 15a. Therefore, the light emission characteristics and / or the electron transport characteristics of the modified sub-region 61a of the wetting layer 61 are changed compared to the remaining sub-region 61b of the wetting layer 61.

[0076] Therefore, the produced wafer 60 includes a substrate 11, at least one intermediate layer 12, 13 and 14 formed on the surface 11a of the substrate 11, wherein at least one intermediate layer 12, 13 and 14 at least partially covers the surface 11a of the substrate 11, and wherein the outer surface 15 of at least one intermediate layer 12, 13 and 14 points away from the surface 11a of the substrate 11. The produced wafer 60 also has a wetting layer 61 that at least partially covers the outer surface 15 of at least one intermediate layer 12, 13 and 14, wherein the at least one intermediate layer 12, 13 and 14 is formed in the following manner: the modification position 15a of the changed sub-region 61a of the wetting layer 61 is predetermined on the outer surface 15 of the at least one intermediate layer 12, 13 and 14, and wherein the changed sub-region 61a of the wetting layer covering the modification position 15a has a different wetting layer thickness and / or a different wetting layer composition than the remaining sub-region 61b of the wetting layer 61 covering the outer surface 15 of the at least one intermediate layer 12, 13 and 14 around the modification position 15a, so that the light emission characteristics and / or electron transport characteristics of the changed sub-region 61a of the wetting layer 61 are different from those of the remaining sub-region 61b of the wetting layer 61.

[0077] Figure 7 An embodiment of a light emitting device 70 is shown.

[0078] The light emitting device 70 is Figure 7 . A wafer 71 produced according to any of the foregoing embodiments is placed into a housing 72 of a light emitting device 70. Exemplarily, the wafer 71 emits a photon beam 73 that passes through an opening 74 of the housing 72. The light emitting device 70 can be configured as a laser, an LED, a superluminescent LED, a single photon source, or any other optical device that emits photons.

[0079] Fig. 8A and Figure 8B A schematic diagram and simulation results for illustrating another embodiment of a method of characterizing a system for producing wafer 80 are shown.

[0080] like Fig. 8AAs shown, firstly a wafer 80 is produced according to any one of the above-described methods. Thus, the wafer 80 can be formed according to any one of the wafers 10, 20, 30, 40, 50 and 70. At least one material of at least one intermediate layer 83 of the wafer 80 and / or its nanostructures (not shown) is deposited by at least one material source 81 of the system. Due to the (usually) angle-dependent flow density of the molecular beam 82 emitted by the at least one material source 81, the thickness profile of the at least one intermediate layer 83 is not completely flat, but has regions 84 of enhanced roughness, such as regions of enhanced concentration of monolayer steps 84. These regions 84 of enhanced roughness are used as growth sites 84 of nanostructures (not shown), such as quantum dots. Instead of the growth of nanostructures, the above-mentioned wetting layer comprising modified sub-regions can also be formed.

[0081] After the nanostructures / quantum dots are grown at the growth locations 84 (or after the wetting layer comprising the modified sub-regions is grown), at least one measurement is performed on the produced nanostructures (or modified sub-regions) of the wafer 80 to determine the flow density profile of at least one material source 81 of the system. For example, at least one photoluminescence measurement of the wafer 80 may be performed.

[0082] The results of the step distribution simulation are shown in Figure 8B The light stripes 85 show the locations of the grown quantum dots, which correspond to an area 84 of enhanced roughness of the basic intermediate layer 83 , while the dark areas 86 correspond to flat areas of the basic intermediate layer 83 .

[0083] The information received from the measurements on the produced wafers 80 is then used to determine the flow density of at least one material source 81. Preferably, the at least one material source 81 of the system under consideration is an effusion unit, but may be any other type of suitable material source.

[0084] Knowing the flow density of at least one material source 81 allows for significant improvements in the epitaxial process performed by the system. For example, the amount and spatial distribution of material deposition can be adapted to the known flow density of at least one material source 81 in order to form a completely flat wafer surface. In addition, arbitrary thickness profiles can be formed with an accuracy as low as one monolayer. The device output per wafer can be maximized by the above method.

[0085] Fig. 9 A second example of a wafer 90 that may be used to perform the above-described method is shown. Fig. 9 The wafer 90 shown in FIG. 1 includes a first material source ( Fig. 9The first basic intermediate layer 91a is formed by a first material source (not shown) having a first non-uniform flow density (e.g., radial emission non-uniformity and / or a non-uniform flow density caused by the angle of the material source relative to the substrate). The first basic intermediate layer 91a has a first thickness profile with a first plurality of monolayer steps. The first basic intermediate layer 91a is covered by a first covering layer 92a having such a small thickness that the monolayer scale roughness of the first basic intermediate layer 91a still exists on the outer surface of the first covering intermediate layer 92a, on which a first plurality of quantum dots 93a having a first dielectric height h1 are grown. This structure is covered by a spacing intermediate layer 94a having a flat surface pointing away from the first plurality of quantum dots 93a.

[0086] Then, the second basic intermediate layer 91b is passed through a second material source ( Fig. 9 The second basic intermediate layer 91b has a second thickness profile with a second plurality of monolayer steps. The second covering layer 92b is formed on the second basic intermediate layer 91b, wherein the second covering layer 92b has such a small thickness that the monolayer scale roughness region of the second basic intermediate layer 91b still exists on the outer surface of the second covering intermediate layer 92b. A second plurality of quantum dots 93b having a second dielectric height h2 different from the first dielectric height h1 is formed on the outer surface of the second covering intermediate layer 92b.

[0087] The base interlayers 91a and 91b are formed by using two different material sources whose flow densities are to be determined. The cover interlayer provides a growth location for the first plurality of quantum dots 93a and the second plurality of quantum dots 93b. The spacer interlayers 94a and 94b are preferably thick enough to provide a flat surface without uneven parts or other irregularities.

[0088] An advantage of the wafer 90 is that the flux densities of two different material sources can be measured in two subsequent or parallel photoluminescence measurements using only a single wafer 90. This is due to the two sets of quantum dots 93a and 93b having different dielectric heights h1 and h2, which can emit two different wavelengths of light after excitation, which can be detected separately.

[0089] Although only two groups of multiple quantum dot structures are shown, more than two layers are also conceivable. For this application, other configurations are also conceivable. In addition to the median diameter of quantum dots 93a and 93b, other physical and / or chemical properties of any type of nanostructures 93a and 93b can be used, and any suitable measurement other than photoluminescence for distinguishing between the two groups of nanostructures 93a and 93b can be used as the measurement method.

[0090] Although the present invention has been described above by preferred embodiments, the present invention is not limited thereto but can be modified in many ways. In particular, the present invention can be changed or modified in various ways without departing from the core of the present invention.

[0091] List of reference symbols used

[0092] 10 chips

[0093] 11 Substrate

[0094] 11a, 11b Surface of substrate 11

[0095] 11c, 11d Sides of the substrate 11

[0096] 12 Basic Intermediate Layer

[0097] 13 Covering the middle layer

[0098] 14 Outer middle layer

[0099] 15 The outer surface 15a, 15b of the outer intermediate layer 14 is a region of the outer surface 15

[0100] 15a Growth position / modification position

[0101] 16 Nanostructure

[0102] 20 chips

[0103] 21 Basic Middle Layer

[0104] 22 Uneven part

[0105] 23 Molecular beam

[0106] 24 Material Sources

[0107] 25 Opener and closer device

[0108] 26 Covering the middle layer

[0109] 27 Growth Position

[0110] 28 Nanostructure

[0111] 30 chips

[0112] 40 chips

[0113] 41 Masking

[0114] 42 opening of the mask 41

[0115] 43 Material Deposition

[0116] 44 Basic middle layer

[0117] 45 Uneven part

[0118] 45 Growth Position

[0119] 50 chips

[0120] 51 Second covering middle layer

[0121] 52 Growth position 53 Nanostructure

[0122] 60 chips

[0123] 61 Wetting layer

[0124] 61a: modified sub-region of the wetting layer 61

[0125] 61b The remaining sub-area of ​​the wetting layer 61

[0126] 70 Light emitting devices

[0127] 71 chips

[0128] 72 Shell

[0129] 73 beam

[0130] 74 opening of housing 72

[0131] 80 chips

[0132] 81 Material Source

[0133] 82 Molecular Beam

[0134] 83 basic middle layer

[0135] 84 Enhanced Roughness Area

[0136] 84 Growth Position

[0137] 85 Bright Stripes

[0138] 86 Dark Area

[0139] 90 chips

[0140] 91a The first plurality of nanostructures

[0141] 91b Second plurality of nanostructures

[0142] 92a First covering middle layer

[0143] 92b Second covering middle layer

[0144] 93a The first plurality of nanostructures

[0145] 93b Second plurality of nanostructures

[0146] 94a Intermediate layer

[0147] 94b Intermediate layer

[0148] h1 first medium height

[0149] h2 Height of the second medium

Claims

1. A wafer (10, 20, 30, 40, 50, 71, 80, 90), comprising: A substrate (11); at least one intermediate layer, the at least one intermediate layer being formed on the surface (11a) of the substrate (11), wherein the at least one intermediate layer at least partially covers the surface (11a) of the substrate (11), and wherein an outer surface (15) of the at least one intermediate layer is directed away from the surface (11a) of the substrate (11); and a nanostructure (16, 28, 53, 84, 89, 92, 95) grown on an outer surface of the at least one intermediate layer (15); wherein the at least one intermediate layer is formed in such a way that the growth position (15a, 27, 45, 52, 84) of the nanostructure (16, 28, 53, 84, 89, 92, 95) is predetermined on the outer surface (15) of the at least one intermediate layer, and wherein at least one nanostructure material of the nanostructure (16, 28, 53, 84, 89, 92, 95) is assembled at a growth position (15a, 27, 45, 52, 84) of the nanostructure (16, 28, 53, 84, 89, 92, 95), wherein the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) is formed in such a way that the outer surface (15) has a varying roughness, wherein regions (15a, 84) of the outer surface (15) have a higher roughness and regions (15b) of the outer surface have a lower roughness, and Regions (15a, 84) of the outer surface (15) having a higher roughness are predetermined as growth locations (15a, 84) of nanostructures (16, 93a, 93b) on the outer surface (15).

2. A wafer (10) according to claim 1, wherein the at least one intermediate layer (12, 13, 14) comprises a stack of at least two layers (12, 13, 14), wherein at least two layers (12, 14) of the stack (12, 13, 14) each have a varying layer thickness perpendicular to the surface (11a) of the substrate (11), and wherein the thickness of the stack (12, 13, 14) perpendicular to the surface (11a) of the substrate (11) is constant.

3. The wafer (80, 90) according to claim 1, wherein the at least one intermediate layer (83, 91a, 91b, 92a, 92b) comprises a layer (83, 91a, 91b) having a periodically or randomly varying layer thickness perpendicular to the surface (11a) of the substrate (11).

4. The wafer (10, 71, 80, 90) according to claim 1, wherein the nanostructures (16, 93a, 93b) include nanoislands, droplets, nanoscribes, nanorings, nanopillars, nanowires, nanobelts, nanorods, nanopiles, quantum dots (16, 28, 53, 84, 89, 92, 95), biological cells and / or biological molecules.

5. A light emitting device (70) having a wafer (71) according to claim 1, wherein the light emitting device (70) is a laser, an LED, a super luminescent LED or a single photon source.

6. A method for producing a wafer (10, 71, 80, 90), comprising the following steps: At least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) is formed on a surface (11a) of a substrate (11), wherein the surface (11a) of the substrate (11) is at least partially covered by the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b), and wherein an outer surface (15) of the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) is formed pointing away from the surface (11a) of the substrate (11), and Growing a nanostructure (16, 93a, 93b) on an outer surface (15) of the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b); wherein the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) is formed in such a way that the growth position (15a, 84) of the nanostructure (16, 93a, 93b) is predetermined on the outer surface (15) of the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b), and wherein the nanostructure (16, 93a, 93b) is grown on the outer surface (15) of the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) by depositing at least one nanostructure material of a subsequent nanostructure (16, 93a, 93b) on the outer surface (15) of the at least one intermediate layer in such a manner that the at least one nanostructure material is assembled at a growth position (15a, 84) of the nanostructure (16, 93a, 93b), wherein the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) is formed in such a way that the outer surface (15) has a varying roughness, wherein regions (15a, 84) of the outer surface (15) have a higher roughness and regions (15b) of the outer surface have a lower roughness, and Regions (15a, 84) of the outer surface (15) having a higher roughness are predetermined as growth locations (15a, 84) of nanostructures (16, 93a, 93b) on the outer surface (15).

7. A method according to claim 6, wherein the nanostructure (16, 93a, 93b) is grown on the outer surface (15) of the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) by depositing at least one nanostructure material of a subsequent nanostructure (16, 93a, 93b) on the outer surface (15) of the at least one intermediate layer (12, 13, 14, 83, 91a, 91b, 92a, 92b) in the following manner: the nanostructure (16, 93a, 93b) is formed by self-aggregation, self-assembly, crystallization and / or nucleation of the at least one nanostructure material assembled at the growth position (15a, 84) of the nanostructure (16, 93a, 93b).

8. A method of characterizing a system for producing a wafer (80, 90), comprising the steps of: Producing a wafer (80, 90) using the method according to claim 6 or 7, wherein at least one material of at least one intermediate layer (83, 91a, 91b, 92a, 92b) of the wafer (80, 90) and / or a nanostructure (93a, 93b) of the wafer (80, 90) is deposited by at least one material source (81) of the system; and At least one measurement is performed on the nanostructure (93a, 93b) of the produced wafer (80, 90) to determine the flow density distribution of at least one material source (81) of the system.

9. A method according to claim 8, wherein the layer thickness distribution of the at least one intermediate layer (83, 91a, 91b, 92a, 92b) is checked by the at least one measurement, and the flow density distribution of at least one material source (81) of the system is determined based on the detected layer thickness distribution of the at least one intermediate layer (83, 91a, 91b, 92a, 92b).

10. The method according to claim 8, wherein the wafer (90) is formed with at least one first intermediate layer (91a, 92a) as at least one intermediate layer (91a, 91b, 92a, 92b) of the wafer (80, 90), a first plurality of nanostructures (93a) having a first physical and / or chemical property as nanostructures of the wafer (80, 90), at least one second intermediate layer (91b, 92b) covering the first plurality of nanostructures (93a), and a nanostructure having a different physical and / or chemical property grown on an outer surface of the at least one second intermediate layer (91b, 92b). A second plurality of nanostructures (93b) of a second physical and / or chemical property of the first physical and / or chemical property, wherein at least a first material source (81) of the system is used to deposit the first intermediate layer (91a, 92a), and at least a second material source is used to deposit the second intermediate layer (91b, 92b), and wherein the at least one measurement includes a first measurement of the first plurality of nanostructures (93a) to determine a flow density distribution of the first material source, and includes a second measurement of the second plurality of nanostructures (93b) to determine a flow density distribution of the second material source.

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