Buried structure semiconductor laser and method of manufacturing the same

Abstract

The disclosure provides a buried structure semiconductor laser, comprising a substrate, a buffer layer, an active layer, a cap layer, a contact layer and a buried layer; the substrate is arranged at the bottom, the contact layer is arranged at the top, the buffer layer, the active layer and the cap layer are arranged between the substrate and the contact layer from bottom to top, and both sides are buried by the buried layer; the buffer layer, the active layer and the cap layer are all divided into a laser region and a mode spot converter region; the laser region is a rectangular region, and the mode spot converter region is a trapezoidal region which gradually narrows in the direction away from the laser region with one side of the laser region as the starting width; the contact region of the substrate and the buffer layer is etched to be the same shape as the buffer layer. The disclosure also provides a preparation method of the buried structure semiconductor laser.

Description

Technical Field

[0001] The present disclosure relates to the technical field of optoelectronic devices, and in particular to a buried structure semiconductor laser and a preparation method thereof. Background Art

[0002] Semiconductor lasers are important light source devices in fiber-optic communication systems. When conventional ridge waveguide semiconductor laser devices are directly coupled to optical fibers, coupling losses can reach as high as 10dB due to the mode field mismatch between the optical fiber and the semiconductor waveguide. Furthermore, alignment tolerance is limited, which undoubtedly increases packaging difficulty and cost. A spot converter can almost adiabatically convert the waveguide's asymmetric near-field distribution into a symmetrical input or output near-field, thereby improving both the coupling efficiency and coupling tolerance between the active device and the optical fiber. However, the small size of the waveguide tip of a high-quality spot converter makes it difficult to manufacture using conventional photolithography techniques, resulting in high manufacturing costs for devices integrated with the spot converter. Summary of the Invention

[0003] In view of the above problems, the present invention provides a buried structure semiconductor laser and a preparation method thereof to solve the above problems.

[0004] One aspect of the present disclosure provides a buried structure semiconductor laser, comprising:

[0005] Substrate, buffer layer, active layer, cap layer, contact layer and buried layer;

[0006] The substrate is arranged at the bottom, the contact layer is arranged at the top, the buffer layer, the active layer and the cap layer are arranged from bottom to top between the substrate and the contact layer, and are buried on both sides by the buried layer;

[0007] The buffer layer, active layer, and cap layer are divided into a laser region and a spot converter region. The laser region is a rectangular region, and the spot converter region is a trapezoidal region with a starting width at one side of the laser region and gradually narrowing away from the laser region.

[0008] The contact area between the substrate and the buffer layer is etched into the same shape as the buffer layer.

[0009] Optionally, the laser region and the spot converter region of the buffer layer and the cap layer are of the same size, and the laser region and the spot converter region of the active layer are smaller in width than those of the buffer layer and the cap layer.

[0010] Optionally, the width differences between the laser region and the spot converter region of the active layer and the corresponding regions of the buffer layer and the cap layer are the same.

[0011] Optionally, the buried layer is a current blocking structure composed of an inverted PN structure, or the material of the buried layer is a semi-insulating buried material.

[0012] Optionally, the substrate material is InP, the buffer layer material is InP, the active layer material is InGaAsP or InGaAlAs, the cap layer material is InP, and the buried layer material is a current blocking structure material composed of an InP inverted PN structure or a semi-insulating InP material.

[0013] One aspect of the present disclosure further provides a method for preparing a buried structure semiconductor laser, the method comprising:

[0014] sequentially growing a buffer layer, an active layer and a cap layer on the substrate;

[0015] fabricating a dielectric mask on the cover layer;

[0016] According to the pattern of the dielectric mask, the cap layer, the active layer, and the buffer layer in the area outside the mask pattern are etched to the substrate, so that the buffer layer, the active layer, and the cap layer form a laser area and a spot converter area, wherein the laser area is a rectangular area, and the spot converter area is a trapezoidal area with a starting width at one side of the laser area and gradually narrowing away from the laser area;

[0017] Growing a buried layer on both sides of the buffer layer, the active layer and the cap layer;

[0018] The dielectric mask is removed, and a contact layer is grown on the cap layer.

[0019] Optionally, etching the cap layer, the active layer, and the buffer layer in areas outside the mask pattern to the substrate according to the pattern on the dielectric mask includes:

[0020] According to the pattern of the dielectric mask, etching the cap layer, active layer, and buffer layer in the area outside the mask pattern to the substrate to form the laser region and the pattern spot converter region of the cap layer and buffer layer;

[0021] Then, the active layer is etched according to the pattern of the dielectric mask so that the width difference between the laser region and the spot converter region of the active layer and the corresponding regions of the buffer layer and the cover layer is the same.

[0022] At least one of the above technical solutions adopted in the embodiments of the present disclosure can achieve the following beneficial effects:

[0023] The embodiments of the present disclosure provide a buried structure semiconductor laser, in which the laser and the spot-mode converter are integrated into one body, which can improve the coupling efficiency between the active device and the optical fiber. A high-quality spot-mode converter can be obtained using a common photolithography process, which is beneficial to improving the yield of device manufacturing and reducing device costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1 A schematic diagram of device materials of a buried structure semiconductor laser provided by an embodiment of the present disclosure is shown;

[0026] Figure 2 A schematic diagram of a dielectric mask pattern of a buried structure semiconductor laser provided by an embodiment of the present disclosure is shown;

[0027] Figure 3 A schematic diagram of the material structure of the laser region of a buried structure semiconductor laser provided by an embodiment of the present disclosure after removing the material outside the dielectric mask;

[0028] Figure 4A The material structure diagram of the laser region after etching the active layer provided by the embodiment of the present disclosure is schematically shown;

[0029] Figure 4B The material structure diagram of the mold spot converter area after etching the active layer provided by the embodiment of the present disclosure is schematically shown;

[0030] Figure 5A The material structure diagram of the laser region after mask growth provided by an embodiment of the present disclosure is schematically shown;

[0031] Figure 5B Schematically shows the material structure of the mold spot converter area after mask growth provided by an embodiment of the present disclosure;

[0032] Figure 6A The schematic diagram of the material structure of the laser region after the growth of the contact layer material provided by the embodiment of the present disclosure is shown;

[0033] Figure 6B A schematic diagram of the material structure of the mold spot converter area after the growth of the contact layer material provided by an embodiment of the present disclosure is shown;

[0034] Description of reference numerals:

[0035] Substrate-10; buffer layer-20; active layer-30; cap layer-40; dielectric mask-50; buried material-60; contact layer-70. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0037] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0038] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0039] The embodiments of the present disclosure provide a buried structure semiconductor laser, in which a spot converter is integrated. The laser can be obtained by adopting a common photolithography process and has a low manufacturing cost.

[0040] The buried structure semiconductor laser includes a substrate 10, a buffer layer 20, an active layer 30, a cap layer 40, a contact layer 70 and a buried layer 60; wherein the substrate 10 is arranged at the bottom, the contact layer 70 is arranged at the top, the buffer layer 20, the active layer 30, and the cap layer 40 are arranged from bottom to top between the substrate 10 and the contact layer 70, and are buried on both sides by the buried layer 60; the buffer layer 20, the active layer 30, and the cap layer 40 are evenly divided into a laser area and a spot converter area, the laser area is a rectangular area, and the spot converter area is a trapezoidal area with a starting width of one side of the laser area and gradually narrowing away from the laser area; the contact area between the substrate 10 and the buffer layer 20 is etched to have the same shape as the buffer layer 20.

[0041] The width differences between the laser region and the spot converter region of the active layer 30 and the corresponding regions of the buffer layer 20 and the cap layer 40 are the same.

[0042] Optionally, the buried layer 60 is a current blocking structure formed of an inverted PN structure, or the material of the buried layer 60 is a semi-insulating buried material.

[0043] Optionally, the substrate 10 is made of InP, the buffer layer 20 is made of InP, the active layer 30 is made of InGaAsP or InGaAlAs, the cap layer 40 is made of InP, and the buried layer 60 is made of a current blocking structure material composed of an InP inverted PN structure or a semi-insulating InP material.

[0044] Another embodiment of the present disclosure provides a method for preparing the buried structure semiconductor laser, including operations S1 to S5.

[0045] Figures 1 to 3 4A to 6A and 4B to 6B show the structural changes of the buried structure semiconductor laser during the preparation process. Figures 1 to 3 4A to 6A and 4B to 6B illustrate the preparation process of the buried structure semiconductor laser and further illustrate the structure of the buried structure semiconductor laser.

[0046] In operation S1 , a buffer layer 20 , an active layer 30 , and a capping layer 40 are sequentially grown on a substrate 10 .

[0047] In operation S2 , a dielectric mask 50 is formed on the capping layer 40 .

[0048] like Figure 1 As shown, the substrate 10, the buffer layer 20, the active layer 30, the cap layer 40, and the dielectric mask 50 are grown in sequence.

[0049] like Figure 2 As shown, a mask pattern is made on the dielectric mask 50, wherein the solid line represents the retained area of ​​the buffer layer 20 and the cap layer 40 after etching, and the dotted line represents the retained area of ​​the active layer 30 after etching. Figure 2 The left area in the figure is the laser LD area, and its width in the solid line figure is W2; Figure 2 The area on the right is the spot converter SSC, and its width gradually decreases from W2 at the laser end to N2 in the solid line diagram; the laser LD area has a width of W1 in the dotted line diagram, and its width is narrower by a on both sides than the solid line diagram; the spot converter SSC has a width gradually decreasing from W1 at the laser end to N1 in the dotted line diagram, and its width is also narrower by a on both sides than the solid line diagram.

[0050] In operation S3, according to the pattern of the dielectric mask 50, the cap layer 40, the active layer 30, and the buffer layer 20 in the area outside the mask pattern are etched to the substrate 10, so that the buffer layer 20, the active layer 30, and the cap layer 40 form a laser area and a spot converter area. The laser area is a rectangular area, and the spot converter area is a trapezoidal area with a starting width of one side of the laser area and gradually narrowing away from the laser area.

[0051] Since the etching width of the active layer 30 is smaller than that of the buffer layer 20 and the cap layer 40 , the etching step is divided into two steps.

[0052] In step 31 , according to the pattern of the dielectric mask 50 , the cap layer 40 , the active layer 30 , and the buffer layer 20 in the area outside the mask pattern are etched to the substrate 10 to form the laser region and the spot converter region of the cap layer 40 and the buffer layer 20 .

[0053] like Figure 3 As shown, according to Figure 2 As shown in the solid line diagram, the cap layer 40, the active layer 30 and the buffer layer 20 in the area outside the mask pattern are removed to the substrate 10 using dry etching or wet etching technology.

[0054] In step 32 , the active layer 30 is etched according to the pattern of the reference mask 50 so that the width difference between the laser region and the spot converter region of the active layer 30 and the corresponding regions of the buffer layer 20 and the cap layer 40 is the same.

[0055] like Figure 4A 、 4B As shown, the active material 30 is selectively etched by wet etching technology, so that its width on both sides is smaller than the width of the dielectric mask 50 by a. In the laser LD region, its width is uniform W1, and in the spot converter SSC region, its width gradually decreases from W1 to N1.

[0056] 4A and 4B, the laser region and the spot converter region of the buffer layer 20 and the cap layer 40 are of the same size, and the width of the laser region and the spot converter region of the active layer 30 is smaller than that of the buffer layer 20 and the cap layer 40 by a on both sides.

[0057] In operation S4 , a buried layer 60 is grown on both sides of the buffer layer 20 , the active layer 30 , and the capping layer 40 .

[0058] refer to Figure 5A 、 5B The buried material is grown on both sides of the buffer layer 20 , the active layer 30 , and the cap layer 40 to form a buried layer 60 , which can be a current blocking structure composed of an inverted pn structure or a semi-insulating material.

[0059] In operation S5 , the dielectric mask 50 is removed, and a contact layer 70 is grown on the cap layer 40 .

[0060] like Figure 6A 、 6B As shown, the contact layer 70 is grown on the cap layer 40 and covers the upper surface of the buried layer 60 .

[0061] In the buried-structure semiconductor laser fabricated using the aforementioned method, the quantum well active layer 30 in the device's laser LD region has a relatively large width, W1, providing excellent light field confinement and contributing to high-quality luminescence. In the device's spot size converter (SSC) region, the quantum well active layer 30 gradually decreases in width, reaching a width of N1 at the device's light-emitting end facet. This smaller width weakens the light field confinement, increasing the near-field spot size at the device's end facet and thus reducing the far-field divergence angle.

[0062] The quantum well active layer width at the tip of the spot converter is N1, which is 2a smaller than the width N2 of the dielectric mask 50. Because N2 is larger, the dielectric mask 50 can be fabricated using conventional photolithography techniques, reducing the difficulty of spot converter fabrication and chip cost. The device's quantum well active material 30 can also be InGaAlAs. The gradual reduction in the width of the dielectric mask 50 in the spot converter region can be linear or nonlinear.

[0063] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or couplings are intended to fall within the scope of this disclosure.

[0064] Although the present disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-described embodiments, but should be determined not only by the appended claims but also by the equivalents of the appended claims.

Claims

1. A buried structure semiconductor laser, characterized in that: include: A substrate (10), a buffer layer (20), an active layer (30), a cap layer (40), a contact layer (70), and a buried layer (60); The substrate (10) is arranged at the bottom, the contact layer (70) is arranged at the top, and the buffer layer (20), the active layer (30), and the cap layer (40) are arranged from bottom to top between the substrate (10) and the contact layer (70), and are buried on both sides by the buried layer (60); The buffer layer (20), the active layer (30), and the cap layer (40) are divided into a laser region and a spot converter region. The laser region is a rectangular region, and the spot converter region is a trapezoidal region with a starting width at one side of the laser region and gradually narrowing in a direction away from the laser region. The laser region and the spot converter region of the buffer layer (20) and the cover layer (40) are of the same size, the laser region and the spot converter region of the active layer (30) are smaller in width than those of the buffer layer (20) and the cover layer (40), and the difference in width between the laser region and the spot converter region of the active layer (30) and the corresponding regions of the buffer layer (20) and the cover layer (40) is the same; A contact area between the substrate (10) and the buffer layer (20) is etched to have the same shape as the buffer layer (20).

2. The buried structure semiconductor laser according to claim 1, characterized in that The buried layer (60) is a current blocking structure formed by an inverted PN structure, or the material of the buried layer (60) is a semi-insulating buried material.

3. The buried structure semiconductor laser according to claim 1, characterized in that The material of the substrate (10) is InP, the material of the buffer layer (20) is InP, the material of the active layer (30) is InGaAsP or InGaAlAs, the material of the cap layer (40) is InP, and the material of the buried layer (60) is a current blocking structure material composed of an InP reverse PN structure or a semi-insulating InP material.

4. A method for preparing a buried structure semiconductor laser, characterized in that: The method comprises: Growing a buffer layer (20), an active layer (30) and a cap layer (40) in sequence on a substrate (10); Making a dielectric mask (50) on the cover layer (40); According to the mask pattern of the dielectric mask (50), the cap layer (40), the active layer (30), and the buffer layer (20) in the area outside the mask pattern are etched to the substrate (10), so that the buffer layer (20), the active layer (30), and the cap layer (40) form a laser area and a spot converter area, wherein the laser area is a rectangular area, and the spot converter area is a trapezoidal area with a starting width of one side of the laser area and gradually narrowing in a direction away from the laser area. The laser region and the spot converter region of the buffer layer (20) and the cover layer (40) are of the same size, the laser region and the spot converter region of the active layer (30) are smaller in width than those of the buffer layer (20) and the cover layer (40), and the difference in width between the laser region and the spot converter region of the active layer (30) and the corresponding regions of the buffer layer (20) and the cover layer (40) is the same; Growing a buried layer (60) on both sides of the buffer layer (20), the active layer (30), and the cap layer (40); The dielectric mask (50) is removed, and a contact layer (70) is grown on the cover layer (40).

5. The preparation method according to claim 4, characterized in that The etching of the cap layer (40), the active layer (30), and the buffer layer (20) from the area outside the mask pattern to the substrate (10) according to the pattern on the dielectric mask (50) comprises: According to the pattern of the dielectric mask (50), etching the cap layer (40), the active layer (30), and the buffer layer (20) in the area outside the mask pattern to the substrate (10), to form the laser region and the pattern spot converter region of the cap layer (40) and the buffer layer (20); Then, according to the pattern of the dielectric mask (50), the active layer (30) is etched so that the laser region and the pattern spot converter region of the active layer (30) have the same width difference as the corresponding regions of the buffer layer (20) and the cover layer (40).

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