Methods and Optoelectronic Devices

Abstract

The present invention relates to an optoelectronic device, comprising a first doped carrier transport [(Al x Ga 1-x ) y In 1-y ] z P 1-z layer (x in the range [0;0.5]) and a second doped carrier transport [(Al x Ga 1-x ) y In 1-y ] z P 1-z (x is in the range of [0; 0, 5]). An active region is disposed between the layers, and the active region is comprised of a plurality of alternating [(Al a Ga 1-a ) b In 1-b ] c P 1-c Quantum well layer and [(Al d Ga 1-d ) e In 1-e ] f P 1-f The barrier layers include a "a" in the range of [0;0.5] and a "d" in the range of [0.45;1], particularly in the range of [0.60;1.0], particularly 0.75 to 1.0. At least one of the quantum well layers and the barrier layers has a concentration of 1e15 cm -3 ~5e17cm -3 In particular, the range of 2e16cm -3 ~7e16cm -3 In the range of intentionally induced dopants, the dopants are selected from at least one of the group: Mg, Zn, Te, and Si.

Description

[Technical Field]

[0001] This application claims priority to WO Patent Application PCT / EP2021 / 072901 (dated 18 August 2021), the disclosure of which is incorporated herein by reference in whole.

[0002] The present invention relates to a method for manufacturing optoelectronic devices. The present invention also relates to optoelectronic devices. [Background technology]

[0003] Optoelectronic devices, also known as lighting diodes or LEDs, require an energy supply for illumination. Charge carriers introduced into the active zone of an optoelectronic device recombine under the emission of light. Recent size reductions have led to the development of μLEDs. The size of a μLED is 1000 μm. 2 It is located in the region less than 10 μm. 2 It can drop to as low as that. At such sizes, avoiding the decrease in quantum efficiency due to surface recombination is crucial for such devices to emit light with both small and large currents. In addition, degradation of device performance has been observed, which also appears to depend on the amount of current flowing through the device.

[0004] Several measures have been proposed to address these and other problems. There is still a need for further means to improve the performance of optoelectronic devices. [Overview of the Initiative]

[0005] This and other objectives are addressed by the subject matter of independent claim 1. Embodiments and further aspects are the subject matter of dependent claims.

[0006] The inventors have found that in optoelectronic devices based on the InGaAlP material system, performance can be increased by intentionally low levels of doping in the active zone of the device. Furthermore, it has been observed that the relationship between the Al content and the low level of doping is such that the efficiency improvement due to the low level of doping increases up to a certain level of the Al content within the quantum barriers of the active zone. This increase in performance can be explained by an improvement in carrier injection into the quantum well stack. Such an increase is independent of the device size, but its effect is more related to reducing the device size and can be combined with other means of improving performance.

[0007] Here, the inventors propose a method for manufacturing an optoelectronic device. After preparing a growth layer, i.e., based on GaAs or any other suitable material, a first doped carrier transport [(Al x Ga 1-x ) y In 1-y z P 1-z layer is deposited on a substrate layer along the growth direction with x in the range of [0.5; 1]. The Al content may be varied according to the needs and requirements and the desired wavelength of the device. Next, an active region is deposited along the growth direction. The active region is configured to generate radiation and includes a plurality of alternating [(Al a Ga 1-a ) b In 1-b c P 1-c quantum well layers and [(Al d Ga 1-d ) e In 1-e f P 1-f barrier layers. The parameter "a" is in the range of [0; 0.5], the parameter "d" is in the range of [0.45; 1], particularly in the range of [0.60; 1.0], particularly 0.75 to 1.0. Next, a second doped carrier transport [(Al x Ga 1-x ) y In 1-y ​​​​z P 1-z The layers are deposited along the growth direction in the range x [0.45;1].

[0008] The parameters y and z may be in the range [0.45;0.55], and b and c are in the range [0.45;0.55].

[0009] According to the proposed principle, the active region is doped with a dopant. For this purpose, a concentration of 1 e15 atoms / cm³ is used. 3 ~5e17 atoms / cm 3 In particular, the range of 1e16 atoms / cm³ 3 ~1e17 atoms / cm 3 In particular, the range of 2e16 atoms / cm³ 3 ~7e16 atoms / cm 3 A dopant within the specified range is added during the deposition of at least one of the quantum well layer and / or barrier layer. The dopant may be selected from the group consisting of Mg, Zn, Te, and Si.

[0010] In some cases, the In content [(Al a Ga 1-a ) b In 1-b ] c P 1-c Quantum well layer and [(Al d Ga 1-d ) e In 1-e ] f P 1-f The barrier layer, parameters 1-b and 1-e are selected so that they differ. For example, parameter 1-b may be in the range of 20%(1-0.8) to 60%(1-0.2), and in particular, 40% to 60%. Similarly, the In content of the barrier layer may be different from or equal to that of the quantum well layer. The In content affects the band gap but also changes the lattice constant. Therefore, changing the In content during the deposition of a multiple quantum well structure may induce some strain within the multiple quantum well structure.

[0011] As a result, in some embodiments, the In content of each barrier layer is equal but differs from that of adjacent quantum well layers. In some embodiments, the difference in In content between adjacent quantum wells and quantum barrier layers induces strain, which may range from -4000 ppm to +4000 ppm. In some embodiments, the In content in the barrier layer is smaller than that in the quantum well layer, inducing overall strain but also increasing the band gap relative to the barrier layer.

[0012] As an overall result, the In content, thickness, or Al content may vary when comparing the barrier layer and the quantum well layer. Therefore, in some embodiments, at least two parameters differ between the barrier layer and the adjacent quantum well layer, the parameters being selected from thickness, Al content, and In content. In some further embodiments, these parameters also differ for each barrier and / or quantum well layer. For example, some barrier layers may have different In content or different thicknesses compared to other barrier layers. This may induce gradual changes in parameters and, therefore, gradual changes in strain within the active region.

[0013] The proposed method intentionally induces additional dopants in at least one of the barriers and / or quantum well layers within the active region. It has been found that the device efficiency increases with this additional intentional doping. It should be noted that while unintended doping during deposition typically occurs, the concentrations involved in such unintended doping are far lower compared to intentionally induced doping. Furthermore, 1e16 atoms / cm³ 3 ~5e17 atoms / cm 3 Higher levels of doping have been observed to be harmful, leading to decreased efficiency and performance.

[0014] As a result, the possible dopant concentration is 1e16 atoms / cm³. 3 ~about 4e17 atoms / cm 3 In the range of 2e16 atoms / cm³, however, more preferably 2e16 atoms / cm³. 3~2e17 atoms / cm 3 The range, or in particular, 5e16 atoms / cm³ 3 ~1.5e17 atoms / cm 3 This is possible. Other doping concentrations described in this application are equally suitable. It has been found that the dopants can be varied, and that two or more dopants can be induced within the active region at the aforementioned concentrations. The doping level of each dopant is 5e17 atoms / cm³. 3 It can be made smaller. Different dopants can be used to dop the quantum well layer and the barrier layer, respectively. Similarly, the doping concentration can be varied between the barrier layer and the adjacent quantum well layer. For example, the doping concentration for the barrier layer may be lower than that for each quantum well layer. Similarly, different dopant materials may be used when depositing or growing the quantum well layer and the barrier layer, respectively.

[0015] In some cases, doping concentrations can be varied in adjacent layers and between layers of the same type, such as quantum well layers or barrier layers. Typical dopants for such purposes can be Te, Zn, Si, Mg, etc.

[0016] This intentional doping may be approximately 10 to 100 times higher than the unintended, inherent dopant concentration in the material. In this regard, the expression “unintended doping” includes not only doping by material impurities, but also all other impurities and natural defects.

[0017] In some embodiments, dopant deposition is performed while depositing material for at least one quantum barrier layer within the active region. Dopant deposition may be performed on multiple layers or for each second or third layer. In some further embodiments, the concentration of the dopant to be added may be varied during the doping step. As a result, it may be preferable to dope barrier layers and / or quantum well layers closer to carrier transport layers with a different concentration than barrier layers and quantum well layers located in the center of the active region. In some other embodiments, the doping concentration may be increased or decreased toward one of the carrier transport layers, i.e., the dopant concentration during the deposition of quantum well layers and barrier layers may be increased or decreased along the growth direction.

[0018] Depositing the active region may involve depositing 3 to 30 quantum well layers, each of which has a thickness of 2 nm to 15 nm, and each of which has a thickness of 3 nm to 25 nm. This generates approximately 7 (3 quantum well layers and 4 barrier layers) to 61 alternating layers within the active region. The thickness and dopant concentration may be varied when depositing the layers, as described above. Depositing the active region may, in particular, involve annealing the deposited alternating quantum well layers and barrier layers in a temperature range of 450°C to 600°C.

[0019] In some embodiments, at least a portion of the multiple barrier layers have different Al content, and the Al content within each barrier layer is constant. Alternatively, the minimum and maximum Al content within the active region differ by a coefficient in the range of 1.1 to 3.5. For example, the Al content of the quantum well layer is in the range of 0.0 to 0.5 (where x is in the range of [0.0;0.5]), and within the barrier layer, it is in the range of 0.6 to 1. The thickness of at least a portion of the barrier layers may vary, and the minimum and maximum thickness of the barrier layers in the active zone differ by a coefficient in the range of 1.5 to 6.

[0020] In some embodiments, the addition of dopants during the deposition of a quantum well layer or barrier layer is slightly delayed compared to the actual deposition of each layer. For example, doping with dopants is performed after the deposition of material for at least one of the barrier layer and quantum well layer has begun. Thus, some of each layer has already grown before the dopants are added. Similarly, in some embodiments, the addition of dopants may be completed before the deposition of material for at least one of the barrier layer and quantum well layer has stopped.

[0021] While doping may be performed on only a single layer or only on specific layers, it has been found that the dopant diffuses into adjacent layers. As a result, optoelectronic devices fabricated by the aforementioned process may exhibit dopant concentration variations across several layers within the active region, a phenomenon known as dopant modulation. Consequently, in some embodiments, dopant modulation is proposed by altering the dopant concentration in adjacent layers, and / or in some other embodiments, by providing an annealing step. This annealing step is performed during the deposition of the active region or after the active region has been formed. Especially in the temperature range of 450°C to 600°C, This can be done. In some embodiments, multiple such steps can be performed after the respective material deposition steps for the barrier and quantum well layers.

[0022] In some further embodiments, an undoped AlGaInP layer may be deposited adjacent to the active region, between the active region and the doped carrier transport layer. The Al content may vary with respect to the Al content of the adjacent carrier transport layer or the Al content of the first layer adjacent to the active region. In some embodiments, the Al content may be the same as that of the adjacent carrier transport layer.

[0023] Several other embodiments relate to further improving the efficiency of the device, which is particularly favored when combined with intentional doping of the active region. In some embodiments, a structured mask layer is deposited. In some embodiments, a second transport layer may also be structured to satisfy the purpose of the structured mask layer. Then, other dopants are deposited, and the second doped carrier transport [(Al x Ga 1-x ) y In 1-y ] z P 1-z The dopant is diffused through the layers into the active region. Further doping increases the dopant concentration, causing quantum well mixing within those regions, resulting in a lateral energy barrier for charge carriers injected into the masked region. The location of the mixed regions is selected so that the various semiconductor layers are separated within those regions, resulting in the formation of device edges with adjacent quantum well mixing. The induced energy barrier prevents charge carriers from non-radiatively recombining along the device edges, improving performance. It has been found that combining both methods results in a performance improvement that exceeds the sum of the individual methods.

[0024] This further deposition and diffusion of dopants (particularly Zn) can be achieved by various means. In some embodiments, the dopant is deposited at a first temperature and diffused at a second temperature, where the second temperature is higher than the first. This approach allows for control of the diffusion of the dopant into the material. In some embodiments, AsH3 or any other As-containing gas can be applied during the diffusion process to saturate Ga or other Type III materials with the As being provided.

[0025] Some further embodiments relate to optoelectronic devices based on the proposed principle of intentionally low levels of doping within the active region. Such optoelectronic devices are first doped carrier transport [(Al x Ga 1-x ) y In 1-y ]z P 1-z Layer (x is in the range [0.5;1]) and second doped carrier transport [(Al x Ga 1-x ) y In 1-y ] z P 1-z (x is in the range [0.5;1]) and the parameter x refers to the Al content, which is constant within both layers and different within each transport layer, but can also vary along a specific direction.

[0026] An active region is located between the two layers, and the active region consists of multiple alternating [(Al a Ga 1-a ) b In 1-b ] c P 1-c Quantum well layer and [(Al d Ga 1-d ) e In 1-e ] f P 1-f Including a barrier layer, "a" is in the range [0;0.5] and "d" is in the range [0.55;1], particularly in the range [0.60;0.90], particularly 0.75-0.85. At least one of the multiple quantum well layers and barrier layers has a concentration of 1e16 atoms / cm³. 3 ~1e17 atoms / cm 3 In particular, the range of 2e16 atoms / cm³ 3 ~7e16 atoms / cm 3 The dopants include intentionally induced dopants in the range of Mg, Zn, Te, and Si, selected from at least one of these.

[0027] In some embodiments, the active region comprises 3 to 30 quantum well layers, each of which has a thickness of 2 nm to 15 nm, and each of which has a thickness of 3 nm to 25 nm. Some of the barrier layers are doped, but the doping concentration may vary between the quantum well layers and the barrier layers. This is called modulation of the dopant concentration. For example, the quantum well layers may contain a lower but still intentional doping level than the barrier layers. As a result, the dopants in the active region extend over multiple alternating quantum well and barrier layers. The expression “intentional doping” or “intentional doping level” refers to a dopant concentration that is much higher (i.e., at least 10 times) than the unavoidable impurities in the material of the active region. Thus, the dopant concentration may vary between different layers, but may decrease or increase toward one of the first and second charge transport layers.

[0028] In some embodiments, the dopant concentration may be highest within the central layer stack of the active region. In some further embodiments, the device may further include an undoped layer positioned between a first doped carrier transport layer and an active region, and at least one of the active region and a second doped carrier transport layer. In some further embodiments, the Al content may vary not only between the barrier and the quantum well layer, but also between adjacent barrier layers. For example, in some embodiments, the minimum and maximum Al content in the active region differ by a coefficient in the range of 1.1 to 1.7.

[0029] The performance of the device based on the proposed principle can be further improved by quantum well mixing in a region located near the edge of the device. In some embodiments, the optoelectronic device further includes a quantum well mixing region, where the dopant concentration in the quantum well mixing region is higher than that in the active region, and the dopant contains Zn in particular, but may also contain Mg. The quantum well mixing region is adjacent to the edge interface of the optoelectronic device.

[0030] Further aspects and embodiments of the proposed principle will become apparent in connection with various embodiments and examples described in detail with respect to the accompanying drawings. [Brief explanation of the drawing]

[0031] [Figure 1] This figure shows embodiments of optoelectronic devices according to several aspects of the proposed principle. [Figure 2] This figure illustrates the dopant concentration across the active region in one embodiment of an optoelectronic device based on the proposed principle. [Figure 3A] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3B] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3C] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3D] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3E] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3F] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3G] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3H] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 3I] This figure illustrates various steps of an embodiment for manufacturing an optoelectronic device according to several aspects of the proposed principle. [Figure 4] This figure shows the performance improvement of optoelectronic devices based on the proposed principle compared to optoelectronic devices that experience unintended doping. [Figure 5] This figure illustrates an example of a doping process for an optoelectronic device to illustrate some aspects of the present disclosure. [Figure 6] This figure shows a typical embodiment of an optoelectronic device to illustrate some aspects of the present disclosure. [Modes for carrying out the invention]

[0032] The following embodiments and examples disclose different aspects and combinations thereof based on the proposed principle. The embodiments and examples are not necessarily in constant proportions. Similarly, different elements may be enlarged or reduced in size to highlight individual aspects. Needless to say, individual aspects of the embodiments and examples shown in the figures can be combined with one another without complex explanation, which is consistent with the principles of the present invention. Some aspects exhibit regular structures or forms. It should be noted that in practice, slight differences and deviations from the ideal form or shape may occur, without contradicting the concept of the present invention.

[0033] Furthermore, individual figures and aspects are not necessarily shown in the correct size, and the proportions between individual elements are not necessarily accurate. Some aspects are emphasized by being shown enlarged. However, terms such as "above," "below," "larger," and "smaller" are correctly expressed in relation to the elements in the figures. Therefore, such relationships between elements can be inferred from the figures.

[0034] FIG. 1 illustrates an embodiment of an optoelectronic device 1 in an AlGaInP material system implementing a low-doped active region according to the present invention. The optoelectronic device 1 includes an n-type contact layer 10a, followed by an n-type carrier distribution and transport layer 20. The contact layer 10a can be made of metal or any other suitable material. The carrier transport layer 20 is based on those having Te or Si as dopants in the AlGaInP material system. An active region 30 is disposed on the n-type carrier transport layer 20 and includes a plurality of quantum well layers 32a, 32b arranged alternately, as well as barrier layers 31a, 31b, and 31c.

[0035] In particular, the first barrier layer 31a of the active region is adjacent to the carrier transport layer 20. Then, a quantum well layer 32a is disposed on the first barrier layer 31a, followed by a second barrier layer 31b. This alternating structure of barrier layers and quantum well layers is repeated up to the last barrier layer 31c.

[0036] On the last barrier layer 31c, a p-type charge carrier transport layer 40 is disposed. On the second charge carrier transport layer 40, a p-type contact layer 50, which also acts as a structured mask in this embodiment, is provided.

[0037] According to the present invention, the aluminum content of the barrier layers 31a, 31b, and 31c within the active region is in the range of [(Al x Ga 1-x ) y In 1-y )] z P 1-z , where x is between [0.60 and 1.00], and in this particular embodiment, x is around 0.8. As a result, the energy bandgap level rises to about 2.4 eV. On the other hand, the aluminum content of the quantum well layers 30a and 30b is [(Al x Ga 1-x ) y In 1-y )] z P 1-z (x is less than 0.5 and corresponds to a bandgap of 1.8 - 1.9 eV).

[0038] According to the proposed principle, the active region 30, particularly the barrier layers 31a, 31b, and 31c, are doped with a low concentration of magnesium (Mg) dopant during the growth of each barrier layer. Other dopants such as Zn, or n-type dopants Te or Si, may also be suitable. Low concentration dopant is referred to as low doping, and is intentional doping compared to unintentional doping or unintentional impurity. Low concentration dopants for low doping are approximately 1e16 to 3e17 atoms / cm³. 3 It may also be within this range. As a result, a significant improvement in quantum efficiency can be obtained with low dopant levels, and therefore, a significant improvement in the device at both low and high current levels. Consequently, an undoped or undoped layer refers to a layer that is intentionally not doped. However, dopants and other impurities may still be present. This is an unavoidable part of the manufacturing process. Furthermore, some diffusion of dopants from doped regions to undoped regions may occur, resulting in a dopant gradient within those regions.

[0039] In addition to this method, quantum well mixing (QWI) may be performed at the outer edge of each device 1, as illustrated in Figure 1. The dotted lines near the edge of the device illustrate the Zn diffusion region, where QWI occurs within its quantum well structure. After structuring the contact layer 50, or after depositing the structured dielectric diffusion mask, quantum well mixing is achieved by depositing a p-type dopant (in particular Zn) and subsequently diffusing it into the various quantum well layers and barrier layers of the p-type transport carrier layer 40 and the active region 30. The induced quantum well mixing results in an increase in the energy band gap in regions located closer to the edge of the device, thus preventing charge carriers in the active region 30 from recombining at the sidewalls due to non-radiative surface recombination. As a result, the ratio between radiative and non-radiative recombination shifts towards radiative recombination.

[0040] Figure 2 shows the changes in dopant concentration across various barrier and quantum well layers within the active region 30 of the device. In contrast to Figure 1, the various layers are rotated 90°. The leftmost layer is layer 20a, located between the doped charge transport layer 20 and the active region 30. The first layer 20a contains AlGaInP material, with an aluminum content close to that of the first barrier layer 31a. An undoped carrier transport layer 20a is not shown in the embodiment of Figure 1, but can be grown on the n-doped charge carrier transport layer 20 and made of the same material.

[0041] A first quantum well layer 32a is located adjacent to the first barrier layer 31a. Following these two layers, multiple barrier and quantum well layers are arranged alternately, overlapping each other. Finally, the last barrier layer 31c is adjacent to the second charge transport layer 40.

[0042] The dopant concentrations are illustrated above the diagrammed structure. During the growth of various barrier layers and quantum layers, dopants (particularly magnesium) are added to the respective barrier layer materials. As a result, the dopant concentrations are relatively high at the location of the barrier layers. In this example, the addition of magnesium or any other dopant is not performed during the growth of the quantum well layers, but only during the deposition of each barrier layer. However, due to the diffusion of each dopant, the dopant concentration inside the quantum well layers is not zero, but decreases to a lower level. This level is diffusion-dependent and can be controlled by the growth process and / or any subsequent annealing step. As a result, the dopant concentrations are modulated across the active regions and decrease only within the adjacent carrier transport layers 20a and 40.

[0043] The diffusion-based concentration modulations illustrated can be adjusted according to the needs and requirements of each device. For example, doping can be performed only during the growth of each barrier layer, as illustrated. However, it is also possible to add dopants during the growth of the quantum well layer. The doping material can be the same but can be varied at different barriers. In some embodiments, doping with magnesium (Mg) or any other suitable dopant can be performed only during the deposition of specific layers within the active region, as illustrated in each barrier layer, and not at all. For example, dopant addition may be performed only in the central layer of the active region, only in the layer adjacent to the carrier transport layer, or only in each third or fourth layer.

[0044] Instead, the dopant concentration can be varied during the dopant addition itself. For example, the doping level can be increased or decreased within each layer, starting from the first barrier layer 31a. 1e16 atoms / cm 3 ~3e17 atoms / cm 3 While dopant concentrations in the range of 1e18 atoms / cm³ can improve the device and increase its performance, 3 Higher doping concentrations within this range were found to be harmful.

[0045] Figures 3A to 3I illustrate the manufacturing of optoelectronic devices using the proposed principle.

[0046] In Figure 3A, a growth substrate 10 is prepared. A first charge carrier transport layer 20 is grown on it. In this embodiment, the charge carrier transport layer 20 is n-type doped AlGaInP-based, and [(Al x Ga 1-x ) y In 1-y ] z P 1-zx has an aluminum content of approximately 0.5 to 1.0. Parameters y and z are in the range of 0.47 to 0.53. Between the first transport layer 20 and the growth substrate 10, two to three sacrificial layers or other layers can be grown to adjust the lattice constant, but this can also provide a smooth surface for the semiconductor layer to be grown thereafter.

[0047] An undoped layer 20a is placed on top of the first n-type doped carrier transport layer 20. Deposition can be easily achieved by reducing or otherwise modifying the dopant concentration when growing the AlGaInP layer 20. Note that the concentration of other dopants in layer 20a can be easily adjusted to reflect the needs of the device.

[0048] In Figure 3C, the first barrier layer 31a of the active region is grown on the undoped layer 20a. This is [(Al x Ga 1-x ) y In 1-y ] z P 1-z The aluminum content x is 0.7 to 0.8. The growth rate for each barrier layer 31a can be reduced so that only a few atoms grow per minute. The overall thickness of the first barrier layer may be in the range of 3 to 20 nm. During the growth of the material for the first barrier layer, a dopant (magnesium in this particular example) is added, thus resulting in a low dopant concentration within the first barrier layer 31a. The dopant concentration is approximately 2 e16 atoms / cm³. 3 Set to this.

[0049] A first quantum well layer 32a is grown on top of the first barrier layer 31a, as illustrated in Figure 3D. The aluminum content of this first quantum well layer 32a is significantly lower than that of the first barrier layer 31a, and may be in the range of x = 0.5. Furthermore, no additional dopants are added during the deposition of the material constituting the first quantum well layer. The thickness of the quantum well layer 32a is selected to be in the same range as the barrier layer, but may be slightly thinner than each of the first barrier layers 31a. The reduction in aluminum content results in a narrower band gap level of approximately 1.9 eV to 2.0 eV compared to the barrier layer, which has a band gap in the range of 2.4 eV.

[0050] In the next step illustrated in Figure 3E, a second barrier layer 31b is grown on the first quantum well layer while dopant elements are added during the deposition phase. The thickness of the second barrier layer 31b is in the same range as the thickness of the first barrier layer in this example, but may be adjusted, for example, to be greater or less than the first barrier layer 31a. In the next step illustrated in Figure 3F, the second quantum well layer 32b is grown again, without adding any further dopants during material deposition.

[0051] The step of stacking alternating barrier and quantum well layers can be repeated until the desired structure of the active region is formed. As shown in this example, magnesium (Mg) is added as a dopant during the deposition stage of the barrier layer material between the growth of each barrier layer. In certain embodiments, the addition of magnesium (Mg) is performed when the growth of the material for each barrier layer has begun and a little after the first atomic layer has grown. In other words, the addition of magnesium as a dopant is slightly delayed during growth and completed a little before the deposition of the material for each barrier layer is finished.

[0052] Figure 3G shows the structure of the active region formed on the carrier transport layer 20, consisting of three typical quantum well layers 32a, 32b, and 32c, and a total of four barrier layers 31a to 31d. A second p-type carrier transport layer 40 is grown on the last barrier layer 31d. A contact layer 50 with a high p-dopant concentration is placed on top of the second carrier transport layer 40.

[0053] The currently existing structure resembles an improved optoelectronic device because the dopant concentration in a specific layer of the active region is low but distinct. As in previous embodiments, modulation of the dopant concentration across the active region is achieved by the diffusion of the dopant material Mg within the adjacent quantum well layer. This diffusion occurs either after the generation of the active region or after a specific step in the growth of the barrier layer and the quantum well layer, respectively. Especially in the temperature range of 450°C to 600°C The process can be controlled to a certain extent by the annealing step.

[0054] Further improvements to optoelectronic devices can be achieved by further introducing quantum well mixing within specific regions of the active area. The region selected for quantum well mixing is closer to the edge of the optoelectronic device to be completed. For this purpose, the contact layer 50 is structured to yield an opening 60, thereby exposing the surface of the p-type doped second carrier transport layer 40. Then, in a subsequent step, the dopant material Zn is deposited on the surface of the second carrier transport layer 40 and on the surface of the structured contact layer 50.

[0055] The deposition of Zn as a dopant is carried out at a first, relatively low temperature. This prevents unintended diffusion into various layers, thus achieving better control of the diffusion depth. Subsequently, the Zn dopant is diffused into the p-type carrier transport layer 40 and the active region 30, and into their respective barriers and quantum well layers, at a second temperature higher than the first temperature.

[0056] Due to the structured contact layer 50, the region where such quantum well mixing occurs does not extend within the quantum well and barrier layer below the structured contact layer 50. In this respect, the contact layer 50 acts as a diffusion mask. As a result, the quantum well mixing region 70 is located at a specific position within the semiconductor material and the active region 30, as illustrated in Figure 3I. The zinc diffusion region extends through the active region 30 near the undoped layer 20a. The region selected for quantum well mixing is located at a position to be used later to isolate various devices, and thus forms the side edges of each device. The band gap within the quantum well mixing region increases so that charge carriers face a repulsive field, preventing charge carriers from reaching the outer edge of the device where surface recombination is highest. Along with intentional low doping of the active region, the performance and efficiency of the quantum device can be further increased.

[0057] Figure 4 illustrates the performance improvement of an optoelectronic device using the proposed principle and the method for manufacturing it, compared to a device manufactured without intentional doping of the active layer. The y-axis of the figure represents the optical output power in arbitrary units, starting at approximately 1200 units and ending at approximately 1800 units.

[0058] Three examples are presented corresponding to multiple optoelectronic devices fabricated using different methods. The first two examples of optoelectronic devices are based on an AlGaInP material system, using an aluminum content of x=0.8 in the barrier layer and 12 unintentionally doped quantum well layers (each layer 3.6 nm wide). The optoelectronic devices measured in these specific examples have a central illumination value of approximately 1400 units, with a 95% confidence interval ranging from approximately 1250 to 1550 units. As a result, without further doping in the active region, approximately 50% of optoelectronic devices fabricated by this conventional method have an illumination of 1400 units.

[0059] In contrast, the rightmost element corresponds to an optoelectronic device having the same aluminum content within the barrier layer and the 12 quantum well layers, each with a thickness of 4 nm. In addition, the active region was doped within the barrier layer using magnesium as a dopant. As shown in this figure, most of the electronic devices fabricated in this way have illumination values ​​approximately 200 units higher and a median value of approximately 1600 units compared to devices without magnesium doping. The 95% confidence interval ranges from 1400 units to approximately 1800 units. This means that further doping can yield a performance improvement of approximately 14%.

[0060] Apart from the additional dopants within the active region, it should also be noted that the quantum well layer thickness is 4 nm, which is about 10% greater than the two previous examples that had 3.6 nm. However, the additional thickness usually results in a decrease in illumination values, and the illumination does not increase significantly, as illustrated. As a result, it can be assumed that performance would be further improved if the quantum well layer thickness were 3.6 nm when intentionally doping the active region with low concentrations. In practice, it was observed that increasing Mg within the active region improved the internal quantum efficiency up to a maximum value, and beyond that, detrimental effects occurred, increasing non-radiative recombination.

[0061] Figure 5 illustrates an example of the doping process in an optoelectronic device based on the proposed principle. This figure also illustrates the doping process for various layer thicknesses, band gaps, and dopant concentration levels. Actual doping levels may vary as the dopant diffuses into adjacent layers. Consequently, the embodiment is a typical one and may vary depending on the different layers, dopant levels, etc.

[0062] The n-type layer has a thickness of approximately 1500 nm and contains an aluminum content x in the material in the range of 0.7 to 1.0. The n-doped layer contains dopant levels due to the n-type dopant DP1, for example, using tellurium or silicon. As shown in the figure, the dopant concentration may change and generally decrease as it approaches the active region, to approximately 2e18 atoms / cm³. 3 It begins at the dopant level. Following the n-type carrier transport layers 20 and 20a on the n side, the active region 30 begins at approximately 2500 nm. The active region 30, which includes multiple quantum barriers and quantum well layers, is located adjacent to the undoped region.

[0063] As shown in the figure, Number 10 16 atoms / cm 3 A second dopant, DP2, at a lower concentration in the range of , is added during the deposition and fabrication of the active region, i.e., during the growth of various barriers and quantum well layers. This additional dopant contains a slightly higher concentration than the unintended existing dopant DP4, which consists mainly of impurities and crystal defects. The unintended doping of DP4 is 1e16 atoms / cm³. 3 It is below that range, and therefore, this is an order of magnitude lower than the intentionally low-doping level of material DP2.

[0064] The material used in DP2 may contain Zn or Mg as the p-type dopant, and silicon (Si) or tellurium (Te) as the n-type dopant. Magnesium as the p-type dopant has been found to be useful in increasing the performance of each device. A p-doped layer structure is grown adjacent to the active region 30. The p-type layer structure has approximately 1e17 atoms / cm². 3 From the initial concentration level, approximately 1e18 atoms / cm³ 3 This includes a second dopant, DP3, which rises to a certain level. As a result, the doping concentrations between n-side 30,30a and p-side 40,40a may differ not only in terms of their minimum and maximum levels, but also in this actual process of doping, as illustrated.

[0065] Figure 6 illustrates a more detailed diagram of an active region having multiple barrier and quantum well layers according to several embodiments of the proposed principle. The thickness of the quantum well layers and barrier layers is approximately 7 nm, and therefore the barrier layers and quantum well layers are at equal distances from each other. However, in some cases and embodiments, the thickness of the quantum well layer can be smaller than the corresponding thickness of the adjacent barrier layer.

[0066] The aluminum content in the quantum well layer is in the range of x = 0 to 0.5, while the aluminum content in the barrier layer reaches approximately x = 0.8. As a result, the AlGaInP barrier layer with a high Al content yields a band gap of approximately 2.4 eV, while the band gap in the quantum well layer is approximately 1.9 eV.

[0067] The lower part of Figure 6 illustrates doping levels for various barrier and quantum well layers. As in the previous example, doping with Mg, Zn, Te, or Si is performed only during the growth of each barrier layer, with the dopant added immediately after the growth of each layer begins and the dopant stopped just before the growth ends.

[0068] No dopants are added during the growth of the material forming the quantum well layer. As a result, the dopant concentration varies between different layers. Furthermore, different dopant concentrations were selected for the barrier layers. In particular, the first two barrier layers 31b and 31c on the left side (closer to layer 20a) contain the same doping level as the right-side barrier layers 31c and 31b adjacent to the p-type doped carrier layer. The dopant concentration levels for these barrier layers are 2e16 atoms / cm³. 3 This is within the range. The two centrally located barrier layers 31d have a density of approximately 4e16 atoms / cm³. 3 It contains higher concentrations of dopants in the range. It becomes clear that the doping level within the quantum well layer changes due to the diffusion of dopants from the barrier layer into the quantum well layer. As a result, the dopant concentration in quantum well layer 32b is 2e16 atoms / cm³ higher than the dopant concentration of the adjacent dopant. 3 From approximately 1e16 atoms / cm³ 3It decreases to 2e16 atoms / cm³ in the adjacent quantum well layer 32c. 3 From 4e16 atoms / cm³ 3 This includes dopant concentrations that increase substantially linearly up to a certain point. This is due to the different doping levels between barrier layers 31d and 31c, respectively. Outside the outermost quantum well layer 32a, the dopant concentration decreases continuously.

[0069] This example illustrates various implementation possibilities for lower levels of doping within the active region of the optoelectronic device according to the present invention. As can be seen from the example, due to diffusion, the dopant concentration may vary in each individual barrier and quantum well layer, and is non-uniform throughout the barrier. Nevertheless, diffusion can be used to obtain the desired concentration profile, as illustrated in Figures 6 and 2, respectively. [Explanation of symbols]

[0070] 1 Optoelectronic devices 10 Growth substrate 20 Doped charge transport layer 20a Undoped layer 30 active area 31a, 31b, 31c, 31d Barrier layer 32a, 32b, 32c Quantum well layer 40 Doped charge transport layer 50 Contact area, structured mask 60 opening 70 Quantum well mixing region DP1, DP2, DP3, DP4 Dopants Zinc diffusion region with QW and QWI

Claims

1. A method for manufacturing optoelectronic devices, The steps include preparing a growth substrate layer, First doped carrier transport [(Al ｘ Ga １－ｘ ) ｙ In １－ｙ ] ｚ P １－ｚ A step of depositing a layer on the substrate layer along the growth direction, wherein x is in the range of [0.5; 1], y is in the range of [0.45; 0.55], and z = 0.5, A step of depositing an active region along the growth direction, wherein the active region is configured to generate radiation and includes a plurality of alternating [(Al ａ Ga １－ａ ) ｂ In １－ｂ ] ｃ P １－ｃ quantum well layers and [(Al ｄ Ga １－ｄ ) ｅ In １－ｅ ] ｆ P １－ｆ barrier layers, where "a" ranges from [0; 0.5], "b" = y, "c" = 0.5, "d" ranges from [0.45; 1.0], and during deposition of at least one of the barrier layer and / or the quantum well layer, doping with a dopant in the range of 1×10 １５ atoms / cm ３ to 5×10 １７ atoms / cm ３ and the dopant is selected from at least one of the group of Mg, Zn, Te, and Si; said step, Second doped carrier transport [(Al ｘ Ga １－ｘ ) ｙ In １－ｙ ] ｚ P １－ｚ The step of depositing a layer along the growth direction, wherein x is in the range of [0.45; 1], and y is in the range of [0.45; 0.55], and z = 0.5, At least one of the quantum well layers is 2 × 10 １６ atoms / cm ３ ~4 x 10 １６ atoms / cm ３ Includes dopants in concentrations within the range of, The doping level of at least one dopant in the at least one quantum well layer differs from the doping level of the adjacent barrier layer. The method, wherein the step of depositing the first doped carrier transport layer includes depositing an undoped [(Al x Ga 1-x) y In 1-y] z P 1-z layer before depositing the active region.

2. The method according to claim 1, wherein the doping is performed during the deposition of at least one quantum barrier layer.

3. The method according to claim 1 or 2, wherein the concentration of the dopant changes during the doping step.

4. The method according to claim 1, wherein the doping with the dopant is performed after the deposition of material on at least one of the barrier layer and the quantum well layer has started and is completed before the deposition of material on at least one of the barrier layer and the quantum well layer has stopped.

5. The method according to claim 1, wherein depositing the active region includes depositing 3 to 30 quantum well layers, each of which has a thickness of 2 nm to 15 nm, and each of which has a thickness of 3 nm to 25 nm.

6. The method according to claim 1, wherein the step of depositing the active region includes annealing the deposited plurality of alternating quantum well layers and barrier layers in a temperature range of 450°C to 600°C.

7. The method according to claim 1, wherein at least a portion of the plurality of barrier layers contain different Al content, the Al content within each barrier layer is constant, and / or the minimum and maximum Al content of the different layers within the active region differs by a coefficient in the range of 1.1 to 3.

5.

8. The method according to claim 1, wherein at least a portion of the barrier layer comprises different thicknesses, and the minimum and maximum thicknesses of the barrier layer within the active zone differ by a coefficient of 1.5 to 6.

9. A method for manufacturing an optoelectronic device, The steps include preparing a growth substrate layer, A step of depositing a first doped carrier transport [(Al x Ga 1-x) y In 1-y] z P 1-z layer on the substrate layer along the growth direction, wherein x is in the range of [0.5; 1], y is in the range of [0.45; 0.55], and z = 0.5, and the step of the above, A step of depositing an active region along the growth direction, wherein the active region is configured to generate radiation and comprises a plurality of alternating [(Al a Ga 1-a) b In 1-b] c P 1-c quantum well layers and [(Al d Ga 1-d) e In 1-e] f P 1-f barrier layers, where "a" is in the range of [0;0.5], "b" = y, "c" = 0.5, and "d" is in the range of [0.45;1.0], and doping at least one of the barrier layers and / or the quantum well layers with a dopant having a concentration in the range of 1 × 10¹⁵ atoms / cm³ to 5 × 10¹⁷ atoms / cm³, wherein the dopant is selected from at least one of the group Mg, Zn, Te, and Si, A second doped carrier transport [(Al x Ga 1-x) y In 1-y] z P 1-z layer is deposited along the growth direction, where x is in the range of [0.45; 1], where y is in the range of [0.45; 0.55], and z = 0.5, the step of At least one of the quantum well layers contains a dopant with a concentration in the range of 2 × 10¹⁶ atoms / cm³ to 4 × 10¹⁶ atoms / cm³. The doping level of at least one dopant in the at least one quantum well layer differs from the doping level of the adjacent barrier layer. The above method further, Depositing a structured mask layer, The dopant is deposited, and the second doped carrier transport [(Al ｘ Ga １－ｘ ) ｙ In １－ｙ ] ｚ P １－ｚ The method comprising diffusing the active region through the layer to obtain a quantum well mixed region.

10. The method according to claim 9, wherein the dopant is deposited at a first temperature and diffused at a second temperature, the second temperature being higher than the first temperature.

11. The method according to claim 9, wherein the dopant is Zn.

12. The method according to claim 9, wherein diffusing the dopant through the second doped carrier transport layer comprises supplying AsH3 or any other group V-containing gas.

13. Optoelectronic devices, First doped carrier transport [(Al ｘ Ga １－ｘ ) ｙ In １－ｙ ] ｚ P １－ｚ Layers (where x is in the range [0.5; 1], y is in the range [0.45; 0.55], and z = 0.5), An active region disposed on the first doped carrier transport layer, wherein the active region is configured to generate radiation and comprises a plurality of alternating [(Al ａ Ga １－ａ ) ｂ In １－ｂ ] ｃ P １－ｃ Quantum well layer and [(Al ｄ Ga １－ｄ ) ｅ In １－ｅ ] ｆ P １－ｆ The active region includes a barrier layer, where "a" is in the range of [0;0.5], "b" = y, "c" = 0.5, and "d" is in the range of [0.45;1.0]. A second doped carrier transport [(Al ｘ Ga １－ｘ ) ｙ In １－ｙ ] ｚ P １－ｚ A layer (where x is in the range [0.45; 1], y is in the range [0.45; 0.55], and z = 0.5) includes, At least one of the plurality of quantum well layers and / or the barrier layer is 1 × 10 １５ atoms / cm ３ ~5 x 10 １７ atoms / cm ３ The dopant comprises a concentration in the range of, wherein the dopant is selected from at least one of the group Mg, Zn, Te, and Si. At least one of the quantum well layers is 2 × 10 １６ atoms / cm ３ ~4 x 10 １６ atoms / cm ３ Includes dopants in concentrations within the range of, The doping level of at least one dopant in the at least one quantum well layer differs from the doping level of the adjacent barrier layer. The aforementioned optoelectronic device further, The optoelectronic device comprising an undoped [(Al x Ga 1-x) y In 1-y] z P 1-z layer disposed between the first doped carrier transport layer and the active region.

14. The optoelectronic device according to claim 13, wherein the active region comprises 3 to 30 quantum well layers, each of the quantum well layers having a thickness of 2 nm to 15 nm, and each of the quantum barrier layers having a thickness of 3 nm to 25 nm.

15. A layer having a changing dopant concentration, disposed between at least one of the first doped carrier transport layers and the active region, and / or The optoelectronic device according to claim 13 or 14, further comprising a layer having a variable dopant concentration, disposed between the active region and the second doped carrier transport layer.

16. At least a portion of the plurality of barrier layers contain different Al content, and the Al content within each barrier layer is constant, and / or The optoelectronic device according to claim 13, wherein the minimum and maximum Al content between the different layers within the active region differs by a coefficient in the range of 1.1 to 3.

5.

17. The optoelectronic device according to claim 13, wherein the dopant within the active region extends over a plurality of alternating quantum well layers and barrier layers.

18. The optoelectronic device according to claim 13, further comprising a quantum well mixed region, wherein the dopant concentration in the quantum well mixed region is higher than the dopant concentration in the unmixed region, and the dopant comprises Zn.

19. The optoelectronic device according to claim 18, wherein the quantum well mixing region is adjacent to the edge interface of the optoelectronic device.

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