CN111261756A - Semiconductor light emitting device - Google Patents
Semiconductor light emitting device Download PDFInfo
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- CN111261756A CN111261756A CN202010219291.9A CN202010219291A CN111261756A CN 111261756 A CN111261756 A CN 111261756A CN 202010219291 A CN202010219291 A CN 202010219291A CN 111261756 A CN111261756 A CN 111261756A
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- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/0004—Devices characterised by their operation
- H01L33/0045—Devices characterised by their operation the devices being superluminescent diodes
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- H01L33/002—Devices characterised by their operation having heterojunctions or graded gap
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/10—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
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Abstract
The embodiment of the invention discloses a semiconductor light-emitting device, which comprises an active layer, a light-emitting layer and a light-reflecting layer, wherein the active layer is provided with a light-emitting end and a reflecting end which are opposite to each other along a waveguide direction; the end face of the reflecting end is not perpendicular to the waveguide direction, and the end face of the reflecting end is not parallel to the end face of the light-emitting end.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a semiconductor light-emitting device.
Background
The semiconductor light emitting device is a kind of optical device made of semiconductor material, including semiconductor laser, semiconductor optical amplifier, semiconductor super-radiation light emitting diode, and semiconductor gain chip. Among them, a semiconductor Super-radiation light emitting Diode (SLD) is used as a spontaneous emission single-pass light amplifier, and its optical performance is between that of a laser and a light emitting Diode. Because the super-radiation light-emitting diode has the characteristics of wide spectrum, short coherence length and the like, the super-radiation light-emitting diode is widely applied to the fields of optical fiber gyroscopes, optical time domain reflectometers, medium-short distance optical fiber communication and the like.
Spectral ripple is an important parameter of such semiconductor light emitting devices, and is caused by chip end face reflection and fiber end face reflection. In the optical fiber gyro system, the spectral ripple can generate a secondary coherent peak to influence the precision of the optical fiber gyro, so how to reduce the spectral ripple of the semiconductor light-emitting device has a very important meaning for the application of the semiconductor light-emitting device.
Disclosure of Invention
In view of the above, embodiments of the present invention provide a semiconductor light emitting device to solve at least one of the problems in the related art.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
an embodiment of the present invention provides a semiconductor light emitting device including an active layer having a light emitting end and a reflecting end opposite to each other in a waveguide direction; wherein the content of the first and second substances,
the end face of the reflecting end is not perpendicular to the waveguide direction, and the end face of the reflecting end is not parallel to the end face of the light-emitting end.
In the above scheme, an angle between the end face of the reflection end and the waveguide direction is 75 ° to 85 °.
In the above scheme, the end face of the light emitting end is perpendicular to the waveguide direction.
In the above scheme, the method further comprises: an upper confinement layer and a lower confinement layer respectively located above and below the active layer;
the upper confinement layer and the lower confinement layer each have an end face coplanar with the reflective end of the active layer in a waveguide direction.
In the above scheme, the method further comprises: the ridge waveguide is positioned on the active layer, and the waveguide direction is the extending direction of the ridge waveguide;
the ridge waveguide has an end face coplanar with the reflection end of the active layer in a waveguide direction.
In the above scheme, the method specifically comprises the following steps: an upper cladding layer and an ohmic contact layer on the active layer;
the upper cladding layer and the ohmic contact layer are provided with a first groove and a second groove along the waveguide direction, and the ridge waveguide is positioned between the first groove and the second groove.
In the above solution, the active layer has a first end and a second end opposite to each other along the waveguide direction, a part of the first end corresponding to the ridge waveguide is the light emitting end, and a part of the second end corresponding to the ridge waveguide is the reflecting end;
the portion of the second end other than the reflective end is perpendicular to the waveguide direction.
In the above scheme, the waveguide direction is perpendicular to a natural cleavage plane of the semiconductor light emitting device.
In the above scheme, the device further comprises a substrate; the active layer is formed on the substrate; the light emitting end and the reflecting end of the active layer are both perpendicular to the surface of the substrate.
In the above scheme, the semiconductor light emitting device is a super-radiation light emitting diode.
The semiconductor light-emitting device provided by the embodiment of the invention comprises an active layer, a light-emitting layer and a reflecting layer, wherein the active layer is provided with a light-emitting end and a reflecting end which are opposite to each other along a waveguide direction; the end face of the reflecting end is not perpendicular to the waveguide direction, and the end face of the reflecting end is not parallel to the end face of the light-emitting end. Thus, in the semiconductor light emitting device provided by the embodiment of the invention, the light transmitted to the reflection end is reflected to the side surface of the waveguide by the end surface of the reflection end, so that the light is absorbed by the side surface of the waveguide through repeated oscillation, the light reflected to the light emitting end is reduced, and finally the spectral ripple is reduced.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
Fig. 1 is a schematic cross-sectional view of a semiconductor light emitting device according to an embodiment of the present invention;
fig. 2 is a schematic cross-sectional view of a semiconductor light emitting device according to another embodiment of the present invention;
fig. 3 is a schematic top view of a semiconductor light emitting device according to an embodiment of the present invention.
Description of reference numerals:
100. 200-a substrate;
201-lower cladding;
102. 202-a lower confinement layer;
103. 203-an active layer;
104. 204-upper limiting layer;
205 — upper cladding layer;
206-ohmic contact layer;
t1 — first groove; t2 — second groove;
a-a light emitting end; a' -reflective end.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present invention; that is, not all features of an actual embodiment are described herein, and well-known functions and structures are not described in detail.
In the drawings, the size of layers, regions, elements, and relative sizes may be exaggerated for clarity. Like reference numerals refer to like elements throughout.
It will be understood that when an element or layer is referred to as being "on" … …, "adjacent to … …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on … …," "directly adjacent to … …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. And the discussion of a second element, component, region, layer or section does not necessarily imply that a first element, component, region, layer or section is present in the invention.
Spatial relationship terms such as "under … …", "under … …", "below", "under … …", "above … …", "above", and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below … …" and "below … …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.
To reduce the spectral ripple of the semiconductor light emitting device, the following scheme may be employed in some embodiments: one solution is to plate an anti-reflection dielectric film on the end face of the light emitting end of the device, and the residual reflectivity of the end face after plating can reach 0.1%, but for high-quality devices, the reflectivity of the dielectric film is required to be lower than 0.01%, and the difficulty in manufacturing the dielectric film with the ultralow reflectivity is very high, and the process repeatability is difficult to guarantee, so that the method is usually implemented in combination with other methods. The other scheme is that a section of absorption area is added in the area close to the end face of the light-emitting end, namely the absorption area is arranged on one side of the light-emitting area, when the device works, current is injected into the light-emitting area only, and the absorption area is not electrified, so that light transmitted in the reverse direction is slowly consumed in the absorption area, and the purposes of suppressing light feedback and reducing spectrum ripple are achieved; however, the absorption region and the light emitting region are generally formed by the same material, and the absorption region and the light emitting region are grown together in the process, and both have the same band gap, so that the absorption region material is substantially transparent to the light transmitted in the reverse direction, which results in that the light transmitted in the reverse direction needs to be absorbed over a longer distance, and thus a longer absorption region length needs to be designed and manufactured, which undoubtedly reduces the chip yield of the epitaxial wafer and increases the product cost. In addition, there is another proposal of adopting an inclined waveguide structure, and making the waveguide structure inclined at a certain angle with respect to the natural cleavage plane of the chip, thereby reducing light reflection at the end face and suppressing oscillation of light in the waveguide, but this proposal has disadvantages of large power loss, low coupling efficiency, and the like.
As mentioned above, the above-mentioned technical solutions for reducing the spectral ripple of the semiconductor light emitting device have certain limitations, and there is still a need in the art to search for new means for reducing the spectral ripple.
Based on this, embodiments of the present invention provide a semiconductor light emitting device. The semiconductor light emitting device includes an active layer having a light emitting end and a reflecting end opposite to each other in a waveguide direction; the end face of the reflecting end is not perpendicular to the waveguide direction, and the end face of the reflecting end is not parallel to the end face of the light-emitting end.
The technical solution of the present invention will be described in further detail with reference to the cross-sectional schematic views of the semiconductor light emitting device in fig. 1 to 2.
First, please refer to fig. 1. Fig. 1 schematically illustrates a constituent structure of a semiconductor light emitting device, and it is to be understood that the semiconductor light emitting device provided by the embodiment of the present invention includes, but is not limited to, a super luminescent diode.
The semiconductor light emitting device includes at least one active layer 103. Here, the active layer 103 may include a bulk material active layer or a multiple quantum well active layer; specifically, the active layer may be an InGaAsP active layer or an InGaAsP/InGaAsP multiple quantum well active layer.
The active layer 103 has a light emitting end a and a reflecting end a' opposite to each other in a waveguide direction; the end face of the reflecting end A 'is not perpendicular to the waveguide direction, and the end face of the reflecting end A' is not parallel to the end face of the light-emitting end A.
The dotted line in fig. 1 shows the waveguide direction of the semiconductor light emitting device; in the present embodiment, the specific structure of the waveguide is not limited. Here, the planar shape of the active layer 103 is, for example, a quadrangle having two ends opposite to each other in the waveguide direction, respectively, the light emitting end a and the reflecting end a ', end faces of the light emitting end a and the reflecting end a' constituting two opposite sides in the quadrangle; the end faces of the side ends of the active layer 103 connecting the light emitting end a and the reflecting end a' form the other two opposite sides in the quadrangle. End faces of both side ends of the active layer 103 except the light emitting end a and the reflecting end a' are parallel to each other. In some embodiments, the semiconductor light emitting device has a non-slanted waveguide, i.e., the waveguide direction is perpendicular to the natural cleavage plane of the device; at this time, the end surfaces of the both side ends are parallel to each other and coincide with the waveguide direction.
In this embodiment, the end surface of the light-emitting end a is a plane. However, the present invention is not limited thereto, and the end surface of the reflection end a' may be a non-planar surface, such as a curved surface or a bent surface. The end face of the light-emitting end A is a plane.
It should be understood that the light emitting end a and the reflecting end a' of the active layer 103 may also be considered as a light emitting end and a reflecting end of the entire semiconductor light emitting device, respectively. The part close to the light emitting end is a light emitting area of the semiconductor light emitting device, and the part close to the reflecting end is a reflecting area of the semiconductor light emitting device.
In order to effectively reduce the spectral ripple of the semiconductor light emitting device, an embodiment of the invention provides a suitable range of the angle between the end surface of the reflective end a 'and the waveguide direction, please refer to fig. 1 and 3, the angle between the end surface of the reflective end a' and the waveguide direction is, for example, β, in a range of 75 ° to 85 °, in an actual manufacturing process, for example, an etching process is performed, so that the active layer 103 is removed at an angle in a range of α °, and α is in a range of 5 ° to 15 °.
The end surface of the light emitting end a may be perpendicular to the waveguide direction. The end face of the light emitting end a is, for example, a naturally cleaved surface of the semiconductor light emitting device. In a specific embodiment, the end surface of the light emitting end a is a natural cleavage surface of the semiconductor light emitting device, and the end surface of the reflecting end a' is a surface processed by an etching process (a surface formed by the etching process and not perpendicular to the waveguide direction).
In this embodiment, the waveguide direction is perpendicular to the natural cleavage plane of the semiconductor light emitting device. It should be understood that, in the present embodiment, the end surfaces of the light emitting end a and the reflecting end a ' are differently processed, so that the end surface of the reflecting end a ' is not perpendicular to the waveguide direction, and the end surface of the reflecting end a ' is not parallel to the end surface of the light emitting end a, thereby reducing the spectral ripple; compared with a device adopting an inclined waveguide structure, the device has the advantages of smaller power loss, higher coupling efficiency and lower product cost. Of course, the embodiment of the present application does not exclude the case where the semiconductor light emitting device adopts an inclined waveguide structure, that is, the case where the waveguide direction is not perpendicular to the natural cleavage plane of the semiconductor light emitting device, and further combines with the improvement of the arrangement of the light emitting end a and the reflection end a'.
In a specific device, the semiconductor light emitting device further includes a substrate 100; the active layer 103 is formed over the substrate 100. Specifically, the semiconductor light emitting device may include a substrate 100 and a multilayer heterostructure on the substrate 100, the multilayer heterostructure including at least the active layer 103.
Here, the substrate 100 is a semiconductor substrate, and a material thereof includes, for example, InP; in some embodiments, the substrate 100 may also be a semiconductor material such as GaAs.
The substrate 100 has two opposite ends in the waveguide direction, wherein one end is parallel to the end surface of the reflective end a 'of the active layer 103 at the included angle α, in other words, one end of the substrate 100 in the waveguide direction is not parallel to the end surface of the reflective end a' of the active layer 103 at an angle ranging from 5 ° to 15 °.
The light emitting end a and the reflecting end a' of the active layer 103 are perpendicular to the surface of the substrate 100.
In a specific device, the semiconductor light emitting device may further include: an upper confinement layer 104 and a lower confinement layer 102 respectively located above and below the active layer 103; the upper confinement layer 104 and the lower confinement layer 102 each have an end face coplanar with the reflection end a' of the active layer 103 in the waveguide direction.
Here, the lower confinement layer 102, the active layer 103, and the upper confinement layer 104 are sequentially formed on the substrate 100.
End faces of the upper confinement layer 104 and the lower confinement layer 102, which are coplanar with the reflective end a' of the active layer 103, constitute a part of a reflective end of the entire semiconductor light emitting device; the other ends of the upper confinement layer 104 and the lower confinement layer 102 in the waveguide direction may be coplanar with the light emitting end a of the active layer 103, which constitutes a part of the light emitting end of the entire semiconductor light emitting device.
The material of the upper confinement layer 104 and/or the lower confinement layer 102 may comprise InGaAsP. The doping concentration of the upper confinement layer 104 and the lower confinement layer 102 may be the same; the thickness may also be the same; but both have a different doping concentration and thickness from those of the active layer 103. The upper confinement layer 104 and the lower confinement layer 102 may also be referred to as an upper waveguide layer and a lower waveguide layer, respectively.
During fabrication, the upper confinement layer 104 and the lower confinement layer 102 may be etched together with the active layer 103 to form the coplanar end faces.
Fig. 2 is a schematic cross-sectional view of a semiconductor light emitting device according to another embodiment of the present invention. The embodiment corresponding to fig. 2 is mainly different from the embodiment corresponding to fig. 1 in that the semiconductor light emitting device shown in fig. 2 has a ridge waveguide structure; still other structural features may be referenced to the corresponding embodiment of fig. 1. The semiconductor light emitting device of fig. 2 may also include: the substrate 200, the lower confinement layer 202, the active layer 203, and the upper confinement layer 204, and the above structure may be the same as the corresponding structure of the semiconductor light emitting device in fig. 1, and will not be described herein again.
In this embodiment, the semiconductor light emitting device may further include: a ridge waveguide on the active layer 203. For the semiconductor light emitting device having the ridge waveguide structure in this embodiment, the waveguide direction is the extending direction of the ridge waveguide. The ridge waveguide has an end surface coplanar with the reflection end a' of the active layer 203 in a waveguide direction.
Specifically, the semiconductor light emitting device includes: an upper cladding layer 205 and an ohmic contact layer 206 on the active layer 203; the upper cladding layer 205 and the ohmic contact layer 206 have a first groove T1 and a second groove T2 in a waveguide direction, and the ridge waveguide is located between the first groove T1 and the second groove T2.
Here, the upper cladding layer 205 is, for example, a P-type layer; the material includes, for example, InP or InGaAsP, etc.
The upper cladding layer 205 and the ohmic contact layer 206 may be sequentially positioned on the active layer 203.
In a specific embodiment, the semiconductor light emitting device may further include: a lower cladding layer 201 underlying the active layer 203. The lower cladding layer 201 is, for example, an N-type layer; the material includes, for example, InP or InGaAsP, etc.
The first groove T1 and the second groove T2 may be obtained by etching the upper cladding layer 205 and the ohmic contact layer 206. When the first groove T1 and the second groove T2 are formed by etching, a sidewall of the first groove T1 facing the ridge waveguide and a sidewall of the second groove T2 facing the ridge waveguide may be made parallel. The extending direction of the first groove T1 and the extending direction of the second groove T2 may be perpendicular to a natural cleavage plane of the semiconductor light emitting device such that the extending direction of the ridge waveguide is perpendicular to the natural cleavage plane.
At least one of the following may be formed after the first and second grooves T1 and T2 are formed: end faces of the reflective end a ' of the active layer 203, the upper confinement layer 204, and the lower confinement layer 202, which are coplanar with the reflective end a ' of the active layer 203, and end faces of the ridge waveguide, which are coplanar with the reflective end a ' of the active layer 203.
In the actual manufacturing process, for example, the above structures of the layers are formed on the substrate 200; here, each layer structure includes at least the active layer 203; in addition, at least one of the following may also be included: a lower cladding layer 201, a lower limiting layer 202, an upper limiting layer 204, an upper cladding layer 205, and an ohmic contact layer 206; of course, other suitable functional layers may also be included. The above-described layer structures are deposited on the substrate 200, for example, by an epitaxial growth process, and thus, the preparation of an epitaxial wafer is completed. Etching the epitaxial wafer to form the ridge waveguide; specifically, for example, the first groove T1 and the second groove T2 penetrating the upper cladding layer 205 and the ohmic contact layer 206 are formed, and the portions of the upper cladding layer 205 and the ohmic contact layer 206 between the first groove T1 and the second groove T2 are formed as the ridge waveguide. Then, carrying out the etching process again to form the reflecting end A'; specifically, for example, the ohmic contact layer 206, the upper cladding layer 205, the upper confinement layer 204, the active layer 203, and the lower confinement layer 202 are etched to form the reflective end a 'and an end face coplanar with the reflective end a'; the etching process is stopped above the lower cladding layer 201, specifically at the interface between the lower cladding layer 201 and the lower confinement layer 202, for example, and the etching process is not stopped inside the lower cladding layer 201.
The etching process for forming the reflective end a' may include a dry etching process and a wet etching process. Before the dry etching process is performed, a photolithography process may be used to define the region to be etched. In the dry etching process, a predetermined thickness may be etched away from the epitaxial wafer, for example, the pattern of the mask plate in the photolithography process may be transferred to the epitaxial wafer; and then, etching downwards along the pattern boundary formed by the dry etching process through a wet etching process until a required structure is formed.
The etching process for forming the reflection end a' is performed, for example, in a range corresponding to the ridge waveguide. In this way, the end face of the active layer 203 falling into the perpendicular projection of the ridge waveguide is etched to form the reflection end a' which is not perpendicular to the waveguide direction.
In a specific device, the active layer 203 has a first end and a second end opposite to each other along a waveguide direction, a portion of the first end corresponding to the ridge waveguide is the light emitting end a, and a portion of the second end corresponding to the ridge waveguide is the reflecting end a'; the part of the second end except the reflection end A' is perpendicular to the waveguide direction. In other words, the reflective end a' is a portion of the second end, specifically, a portion corresponding to the ridge waveguide. The second end of the active layer 203 has an outer end surface (e.g., a natural cleavage surface) perpendicular to the waveguide direction, and the end surface of the reflective end a' is connected to the outer end surface on one side and recessed within the outer end surface on the other side in a direction parallel to the plane of the substrate 200.
It should be noted that, in this embodiment, although the case where the semiconductor light emitting device has a ridge waveguide structure is described; it should be understood that the technical solution of the present invention is also applicable to a semiconductor light emitting device having a non-ridge waveguide structure according to the corresponding embodiment of fig. 1. Moreover, even for a semiconductor light emitting device with a ridge waveguide structure, the technical scheme of the invention is not only suitable for the case that the ridge waveguide structure is formed by an upper cladding layer and an ohmic contact layer, or the active layer is not ridge-shaped, but also can be adopted to solve the problem of reducing the spectral ripple for other ridge waveguide structures.
In a specific embodiment, the semiconductor light emitting device may further include: an upper metal electrode and a lower metal electrode. The upper metal electrode is connected with the ohmic contact layer for example; and forming the ohmic contact layer on the substrate by evaporation or sputtering. The lower metal electrode is positioned on the back surface of the substrate for example; after thinning the substrate, forming on the back side of the substrate.
It should be noted that, in order to further reduce the spectral ripple, the technical means for reducing the spectral ripple of the semiconductor light emitting device provided in each embodiment of fig. 1 and 2 of the present invention may be used in combination with the technical means provided in other embodiments; for example, the method is combined with other technical means such as plating an anti-reflection dielectric film on the end face of the light-emitting end, increasing an absorption area in the area close to the end face of the light-emitting end and the like; furthermore, the combination with a slanted waveguide structure is not excluded.
The positive effects of the present invention will be described in further detail with reference to a specific example.
This specific example provides a technical solution for effectively reducing spectral ripples of a superluminescent light emitting diode, and overcomes the defects in the conventional scheme for reducing spectral ripples.
Firstly, a method for preparing a super-radiation light-emitting diode is provided, the method comprises the following steps: epitaxially growing a multilayer heterostructure on a semiconductor substrate in sequence, for example, the multilayer heterostructure sequentially comprises a lower cladding layer, a lower limiting layer, an active layer, an upper limiting layer, an upper cladding layer and an ohmic contact layer; the active region is provided with an inclined surface at one end of the waveguide along the waveguide direction to reduce light reflection, and the other end surface is a planar light emitting end. Then, an upper metal electrode is manufactured on the waveguide, and a lower metal electrode is manufactured after the chip is thinned.
The inclined end surface of the super-radiation light-emitting diode prepared by the method is independently manufactured into an etching area through a photoetching process after a channel (a groove for forming a ridge waveguide) is etched, and the etching area is respectively etched by a dry method and a wet method. The method has the advantages that the front end and the rear end of the epitaxial wafer are made of the same material, the chip structure is simple, and compared with the inclined cavity ridge waveguide chip, the power loss is small, the coupling efficiency is high, and the epitaxial growth cost is low. The spectrum ripple is effectively reduced, the chip yield of the epitaxial wafer is improved, and the chip cost is reduced.
Secondly, the specific example also provides a super-radiation light emitting diode structure, wherein the structure consists of a semiconductor substrate and a multilayer heterostructure which is epitaxially grown on the semiconductor substrate in sequence, and the structure sequentially comprises a lower cladding layer, a lower limiting layer, an active layer, an upper limiting layer, an upper cladding layer and an ohmic contact layer; the front end of the structure is a luminous area and is vertical to the end face, and the rear end of the structure is a reflecting area and has an inclination angle with the end face of the chip. The structure may further include an upper metal electrode located on the waveguide, and a lower metal electrode located under the semiconductor substrate.
The core of the technical scheme is that the active region end face of the super-radiation light-emitting diode is subjected to different treatments along the waveguide direction, the front ridge end face is a light-emitting region and is perpendicular to the chip end face, the rear ridge end face is a reflecting region and forms a certain angle α (5-15 degrees) with the chip end face, the reflecting ridge end face reflects light to the side face of the waveguide for repeated oscillation and absorption, reflected light reflected to the light-emitting end is reduced, and the purpose of reducing spectral ripples is achieved.
The embodiments of the invention are applicable to all semiconductor super-radiation light-emitting diodes with double-heterojunction structures; the material is suitable for various material systems, such as InGaAsP/InP material, AlGaInAs/InP material, AlGaAs/GaAs material and other material systems; the method is suitable for various planar active layer buried heterostructures, such as a corrosion mesa buried structure, a double-groove planar buried structure, a strip buried heterojunction and the like; the method is suitable for various non-planar active layer buried heterostructures, such as a V-groove substrate or channel substrate buried structure, a mesa substrate buried heterostructure, a buried crescent structure and the like.
The technical features described in the embodiments of the present invention may be arbitrarily combined without conflict with each other.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.
Claims (10)
1. A semiconductor light emitting device comprising an active layer having a light emitting end and a reflecting end opposite to each other in a waveguide direction; wherein the content of the first and second substances,
the end face of the reflecting end is not perpendicular to the waveguide direction, and the end face of the reflecting end is not parallel to the end face of the light-emitting end.
2. The semiconductor light emitting device of claim 1, wherein an angle between the end face of the reflective end and the waveguide direction is in a range of 75 ° to 85 °.
3. The semiconductor light emitting device according to claim 1, wherein an end face of the light emitting end is perpendicular to a waveguide direction.
4. The semiconductor light emitting device according to claim 1, further comprising: an upper confinement layer and a lower confinement layer respectively located above and below the active layer;
the upper confinement layer and the lower confinement layer each have an end face coplanar with the reflective end of the active layer in a waveguide direction.
5. The semiconductor light emitting device according to claim 1, further comprising: the ridge waveguide is positioned on the active layer, and the waveguide direction is the extending direction of the ridge waveguide;
the ridge waveguide has an end face coplanar with the reflection end of the active layer in a waveguide direction.
6. The semiconductor light emitting device according to claim 5, specifically comprising: an upper cladding layer and an ohmic contact layer on the active layer;
the upper cladding layer and the ohmic contact layer are provided with a first groove and a second groove along the waveguide direction, and the ridge waveguide is positioned between the first groove and the second groove.
7. The semiconductor light emitting device according to claim 5, wherein the active layer has a first end and a second end opposite to each other in a waveguide direction, a portion of the first end corresponding to the ridge waveguide being the light emitting end, and a portion of the second end corresponding to the ridge waveguide being the reflecting end;
the portion of the second end other than the reflective end is perpendicular to the waveguide direction.
8. The semiconductor light emitting device of claim 1, wherein the waveguide direction is perpendicular to a natural cleavage plane of the semiconductor light emitting device.
9. The semiconductor light emitting device of claim 1, further comprising a substrate; the active layer is formed on the substrate; the light emitting end and the reflecting end of the active layer are both perpendicular to the surface of the substrate.
10. The semiconductor light emitting device of claim 1, wherein the semiconductor light emitting device is a superluminescent light emitting diode.
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