Photonic crystal laser and preparation method thereof

Abstract

The invention discloses a photonic crystal laser and a preparation method thereof, the photonic crystal laser comprises a substrate layer and a light emitting unit located on the substrate layer, and the light emitting unit comprises an epitaxial structure layer and a photonic crystal layer located on the epitaxial structure layer; the epitaxial structure layer comprises a first contact layer, a first limiting layer, an active layer, a second limiting layer and a second contact layer which are sequentially stacked in the direction parallel to the surface of the substrate layer; and photonic crystals which are periodically arranged at intervals are formed in a partial region of the photonic crystal layer. The electric injection efficiency is improved by transversely preparing the epitaxial structure layer, the active layer is coupled with the photonic crystal layer in the vertical direction after emitting light, and laser beams are emitted in the vertical direction.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a photonic crystal laser and its fabrication method. Background Technology

[0002] With the development of semiconductor lasers, vertical-cavity surface-emitting lasers (VCSELs) and edge-emitting lasers have been widely used in real-world applications. However, in fields such as optical communication, laser cutting, and radar detection, these lasers generally suffer from problems such as large output laser divergence angles and difficulty in increasing single-mode output power. In contrast, photonic crystal lasers exhibit significant advantages, including single-mode vertical emission, narrow linewidth, extremely low divergence angle, and high output power. Currently, electrically pumped photonic crystal lasers mostly employ vertical secondary epitaxy processes, achieving operation by fabricating upper and lower metal electrodes. However, this approach suffers from problems such as high threshold power, poor uniformity of secondary epitaxy, and high difficulty in electrode fabrication.

[0003] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a photonic crystal laser and its fabrication method. Summary of the Invention

[0004] The purpose of this invention is to provide a photonic crystal laser and its fabrication method, which can increase the electrical injection efficiency by preparing an epitaxial structure layer laterally, and after the active layer emits light, it couples with the photonic crystal layer in the vertical direction to emit a laser beam in the vertical direction.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0006] A photonic crystal laser includes a substrate layer and a light-emitting unit located on the substrate layer, wherein the light-emitting unit includes an epitaxial structure layer and a photonic crystal layer located on the epitaxial structure layer;

[0007] The epitaxial structure layer includes a first contact layer, a first confinement layer, an active layer, a second confinement layer, and a second contact layer, which are sequentially stacked along a direction parallel to the surface of the substrate layer.

[0008] A portion of the photonic crystal layer is formed with periodically spaced photonic crystals.

[0009] In one or more embodiments of the present invention, the photonic crystal laser further includes a first electrode and a second electrode located on a substrate layer, the first electrode being formed beside the first contact layer, and the second electrode being formed beside the second contact layer; and / or,

[0010] The substrate layer includes a silicon wafer and an oxide layer on the silicon wafer, the oxide layer facing the light-emitting unit.

[0011] In one or more embodiments of the present invention, the photonic crystal laser includes a plurality of light-emitting units periodically arranged on a substrate layer, and a first passivation layer or a second passivation layer is disposed between adjacent light-emitting units.

[0012] Another aspect of the present invention provides a method for fabricating a photonic crystal laser, the method comprising:

[0013] A composite substrate is provided, the composite substrate comprising a substrate layer and a semiconductor layer located on the substrate layer;

[0014] The semiconductor layer is patterned and etched to form a plurality of periodically spaced microstructures, the microstructures including a first sidewall and a second sidewall disposed opposite to each other;

[0015] A first passivation layer is prepared, which covers the upper surface and the first sidewall of the microstructure;

[0016] A portion of the microstructure is removed from the second sidewall of the microstructure in the direction toward the first sidewall, and the remaining microstructure forms the first contact layer;

[0017] A first confinement layer, an active layer, a second confinement layer, and a second contact layer are sequentially stacked from the surface of the first contact layer in a direction away from the first sidewall to form an epitaxial structure layer;

[0018] A photonic crystal is fabricated within a portion of the first passivation layer located above the epitaxial structure layer.

[0019] In one or more embodiments of the present invention, the preparation method further includes:

[0020] The first passivation layer and the epitaxial structure layer are etched sequentially to form a first through-groove, and a second passivation layer is prepared in the first through-groove. The size of the second passivation layer in the thickness direction is greater than or equal to the size of the epitaxial structure layer in the thickness direction, and the size of the second passivation layer in the thickness direction is less than the distance between the surface of the first passivation layer and the substrate layer.

[0021] In one or more embodiments of the present invention, the preparation method further includes: removing a portion of the first passivation layer using a wet etching process to form a second through groove within the first passivation layer that exposes the first contact layer.

[0022] In one or more embodiments of the present invention, the preparation method further includes:

[0023] A second electrode is fabricated next to the second contact layer;

[0024] A first electrode is prepared in the second through groove, and the first electrode is brought into contact with the exposed surface of the first contact layer.

[0025] In one or more embodiments of the present invention, a wet etching process is used to remove a portion of the microstructure from the second sidewall of the microstructure in the direction toward the first sidewall, with an etching depth of 5~20μm.

[0026] In one or more embodiments of the present invention, the semiconductor layer is patterned and etched to form a plurality of periodically spaced microstructures, including:

[0027] A patterned mask layer is grown on the surface of the semiconductor layer;

[0028] Part of the semiconductor layer is etched using the first etching process.

[0029] In one or more embodiments of the present invention, the preparation method further includes: preparing a composite substrate based on a Smart-Cut process.

[0030] In one or more embodiments of the present invention, the microstructure has a dimension of 200-500 μm along the width direction, and the spacing between two adjacent microstructures is greater than or equal to 30 μm.

[0031] The spacing between adjacent first passivation layers is 10~30μm;

[0032] The photonic crystal layer has a thickness dimension of 100~500nm.

[0033] Compared with existing technologies, the photonic crystal laser and its fabrication method of the present invention, through the lateral fabrication of the epitaxial structure layer and the coupling of the active layer with the photonic crystal layer in the vertical direction after emission, emits a laser beam in the vertical direction. This invention significantly increases the electrical injection efficiency and avoids the power loss caused by traditional secondary epitaxial processes. Furthermore, the secondary epitaxy in this invention exhibits good uniformity and is less difficult to fabricate electrodes. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the photonic crystal laser in Embodiment 1 of the present invention;

[0036] Figure 2 In Embodiment 1 of the present invention Figure 1 Top view of the photonic crystal laser shown;

[0037] Figure 3 In Embodiment 1 of the present invention Figure 1 A partially enlarged schematic diagram of region 21a of the photonic crystal laser shown;

[0038] Figure 4 This is a schematic diagram of the structure of a photonic crystal laser in another embodiment of the present invention;

[0039] Figure 5 In Embodiment 1 of the present invention Figure 4 Top view of the photonic crystal laser shown;

[0040] Figure 6 This is a schematic diagram of the composite substrate structure in Embodiment 1 of the present invention;

[0041] Figure 7 This is a schematic diagram of the process for preparing the microstructure in Example 1 of the present invention;

[0042] Figure 8 This is a schematic diagram of the substrate layer and microstructure in Embodiment 1 of the present invention;

[0043] Figure 9 In Embodiment 1 of the present invention Figure 8 A top view of the substrate and microstructure shown;

[0044] Figure 10 This is a schematic diagram of the substrate layer, microstructure, and first passivation layer in Embodiment 1 of the present invention;

[0045] Figure 11 In Embodiment 1 of the present invention Figure 10 Top view of the structure shown;

[0046] Figure 12 This is a schematic diagram of the structure of the first contact layer, the first passivation layer, and the substrate layer in Embodiment 1 of the present invention;

[0047] Figure 13 This is a schematic diagram of the structure of the first passivation layer, the epitaxial structure layer, and the substrate layer in Embodiment 1 of the present invention;

[0048] Figure 14 This is a top view of the second passivation layer in Embodiment 1 of the present invention;

[0049] Figure 15 This is a schematic diagram of the structure of the first passivation layer, epitaxial structure layer, substrate layer and second electrode in Embodiment 1 of the present invention;

[0050] Figure 16 In Embodiment 1 of the present invention Figure 15 Top view of the structure shown;

[0051] Figure 17 This is a schematic diagram of the structure of the second through groove in Embodiment 1 of the present invention. Detailed Implementation

[0052] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0053] As mentioned in the background technology, the vertical secondary epitaxial process refers to the current flow and laser emission direction passing perpendicularly through the epitaxial layer. The core structure of an electrically pumped photonic crystal laser is to create a layer with a two-dimensional photonic crystal pattern above or below the active region. Through the bandgap effect of the photonic crystal, resonance is formed in the vertical direction and laser is output.

[0054] A drawback of electrically pumped photonic crystal lasers is their low electrical injection efficiency. After the first epitaxial interruption, the wafer is exposed to the atmosphere, and even after rigorous cleaning, a thin oxide layer and adsorbed contaminants may form on its surface. Furthermore, epitaxial growth on uneven surfaces with etched photonic crystal holes or pillars is highly susceptible to crystal defects such as lattice mismatch, dislocations, and stacking faults. Once injected carriers diffuse into these defective regions, they undergo nonradiative recombination and are consumed. To compensate for this significant loss and achieve the carrier density required for population inversion, a much larger current must be injected.

[0055] To address the aforementioned technical problems, this disclosure provides a photonic crystal laser, comprising a substrate layer and a light-emitting unit located on the substrate layer. The light-emitting unit comprises an epitaxial structure layer and a photonic crystal layer located on the epitaxial structure layer. The epitaxial structure layer comprises a first contact layer, a first confinement layer, an active layer, a second confinement layer, and a second contact layer sequentially stacked along a direction parallel to the surface of the substrate layer. A portion of the photonic crystal layer is formed with periodically spaced photonic crystals.

[0056] On the other hand, this disclosure also provides a method for fabricating a photonic crystal laser, comprising:

[0057] A composite substrate is provided, the composite substrate including a substrate layer and a semiconductor layer located on the substrate layer;

[0058] The semiconductor layer is patterned and etched to form several periodically spaced microstructures, the microstructures including a first sidewall and a second sidewall disposed opposite to each other.

[0059] A first passivation layer is prepared, which covers the upper surface and the first sidewall of the microstructure;

[0060] A portion of the microstructure is removed from the second sidewall of the microstructure along the direction toward the first sidewall, and the remaining microstructure forms the first contact layer;

[0061] A first confinement layer, an active layer, a second confinement layer, and a second contact layer are sequentially stacked on the surface of the first contact layer in a direction away from the first sidewall to form an epitaxial structure layer.

[0062] A photonic crystal is fabricated within a portion of the first passivation layer located above the epitaxial structure layer.

[0063] This invention fabricates an epitaxial structure layer laterally, and after the active layer emits light, it couples with a photonic crystal layer in the vertical direction to emit a laser beam. This invention greatly increases the electrical injection efficiency and avoids the power loss caused by traditional secondary epitaxial processes.

[0064] Example 1:

[0065] Combination Figures 1-3 As shown, this embodiment provides a photonic crystal laser, including a substrate layer 10 and a light-emitting unit, a first electrode 31 and a second electrode 32 located on the substrate layer 10. The light-emitting unit includes an epitaxial structure layer 21 and a photonic crystal layer 22 stacked sequentially along a first direction Y. In this embodiment, the first direction Y is a direction perpendicular to the surface of the substrate layer 10.

[0066] The epitaxial structure layer 21 includes a first contact layer 211, a first confinement layer 212, an active layer 213, a second confinement layer 214, and a second contact layer 215, which are sequentially stacked along the second direction X. In this embodiment, the second direction is parallel to the surface of the substrate layer 10. A portion of the photonic crystal layer 22 has periodically spaced photonic crystals.

[0067] The first electrode 31 is formed beside the first contact layer 211 and in contact with the first contact layer 211, and the second electrode 32 is formed beside the second contact layer 215 and in contact with the second contact layer 215.

[0068] It is understood that in this embodiment, lateral electric drive is used to effectively inject electrons into the active region, so that the current direction is parallel to the substrate layer 10. The first passivation layer 41 located on the sidewall of the active layer 213 is used to prepare the photonic crystal layer 22, so that the light emission direction is perpendicular to the substrate layer 10, which greatly reduces the threshold current of the photonic crystal laser.

[0069] Furthermore, in this embodiment, the substrate layer 10 includes a silicon wafer 12 and an oxide layer 11 located on the silicon wafer, with the oxide layer 11 facing the light-emitting unit, that is, the light-emitting unit is disposed on the oxide layer 11.

[0070] In this embodiment, the first contact layer 211 comprises a III-V compound such as gallium arsenide (GaAs). For example, if the first contact layer 211 is N-type doped, then the second contact layer 215 is P-type doped, and the first confinement layer 212 is an N-type confinement layer and the second confinement layer 214 is a P-type confinement layer. Conversely, if the first contact layer 211 is P-type doped, then the second contact layer 215 is N-type doped, and the first confinement layer 212 is a P-type confinement layer and the second confinement layer 214 is an N-type confinement layer.

[0071] Furthermore, in this embodiment, the photonic crystal layer 22 includes silicon nitride to increase the refractive index. In other alternative embodiments, the photonic crystal layer 22 may be made of materials such as silicon dioxide.

[0072] like Figure 4 and Figure 5 As shown, in another alternative embodiment, the photonic crystal laser includes a plurality of light-emitting units periodically arranged on the substrate layer 10, and... Figure 1 The difference in the laser shown is that, for two adjacent light-emitting units arranged along the second direction X, a first passivation layer 41 is disposed between the second electrode 32 of the light-emitting unit and the first electrode 31 of its adjacent light-emitting unit. A second passivation layer 42 is disposed between two adjacent light-emitting units arranged along the third direction Z. In this embodiment, the third direction Z is a direction parallel to the surface of the substrate layer 10 and perpendicular to the second direction X. It can be understood that... Figure 4 The photonic crystal laser shown can be cut to obtain the desired result. Figure 1 The image shows an independent photonic crystal laser device.

[0073] Combination Figures 6-17 As shown, this embodiment also provides a method for fabricating a photonic crystal laser, including:

[0074] S1, a composite substrate is provided, the composite substrate including a substrate layer 10 and a semiconductor layer 51 located on the substrate layer 10. The substrate layer 10 includes a silicon wafer 12 and an oxide layer 11, wherein, exemplarily, the oxide layer 11 includes silicon dioxide.

[0075] Furthermore, the composite substrate in this embodiment (such as...) Figure 6 (As shown) This was fabricated using the Smart-Cut process. It should be noted that the Smart-Cut process is a semiconductor manufacturing technology used to fabricate thin-film wafers. The core of this Smart-Cut process mainly involves transferring a thin layer of material from one wafer to another while maintaining high crystal quality and flatness. Its core principle is to form a brittle layer between the contact surfaces of the two wafers, and then use stress-induced peeling to transfer the thin film from one wafer to another.

[0076] For example, the fabrication method in this embodiment further includes fabricating a composite substrate based on a Smart-Cut process, specifically including:

[0077] A first silicon wafer is provided, and an oxide layer 11 is formed on the first silicon wafer;

[0078] A second silicon wafer is provided, and a semiconductor layer 51 is epitaxially grown on the second silicon wafer;

[0079] The oxide layer 11 is bonded to the semiconductor layer 51, and the second silicon wafer is removed to obtain a composite substrate.

[0080] It is understood that the Smart-Cut process is well known in the prior art, so its principle will not be described in detail here, and any known or unknown Smart-Cut process can be used here without restriction.

[0081] S2, patterning etching is performed on semiconductor layer 51 to form several periodically spaced microstructures, the microstructures including a first sidewall and a second sidewall disposed opposite to each other.

[0082] Combination Figure 7 As shown, the main steps for preparing the microstructure in this embodiment include:

[0083] 1. A patterned mask layer 60 is grown on the surface of semiconductor layer 51;

[0084] 2. A portion of the semiconductor layer 51 is etched using the first etching process, with the etching depth extending from the surface of the semiconductor layer 51 to the surface of the oxide layer;

[0085] 3. Remove the mask layer 60.

[0086] Combination Figure 8 and Figure 9 As shown, in this embodiment, the dimension w1 of the microstructure 511 along the width direction is 200~500μm, and the spacing w2 between two adjacent microstructures 511 is ≥30μm. It can be understood that the dimension w1 of the microstructure 511 along the width direction is the same as the dimension of the microstructure 511 along the second direction.

[0087] In this embodiment, the microstructure 511 extends along a third direction Z and includes a first sidewall 501 and a second sidewall 502. It can be understood that the first sidewall 501 and the second sidewall 502 are the surfaces exposed after the semiconductor layer 51 is patterned and etched, and the first sidewall 501 and the second sidewall 502 are arranged opposite to each other along a second direction X.

[0088] S3, prepare the first passivation layer 41, the first passivation layer 41 covers the upper surface and the first sidewall of the microstructure 511.

[0089] The spacing between adjacent first passivation layers 41 is 10~30μm. In this embodiment, the spacing between adjacent first passivation layers 41 is 15μm. In other alternative embodiments, the spacing between adjacent first passivation layers 41 can be 10μm or 30μm.

[0090] Combination Figure 10 and Figure 11 As shown, it can be understood that the first passivation layer 41 covers and protects the upper surface of the microstructure 511 (i.e. the surface away from the substrate layer 10) and the first sidewall 501, while the second sidewall 502 of the microstructure 511 is exposed to facilitate subsequent wet etching processes.

[0091] S4, a portion of the microstructure 511 is removed from the second sidewall 502 of the microstructure in the direction toward the first sidewall 501, and the remaining microstructure forms the first contact layer 211.

[0092] like Figure 12 As shown, this embodiment uses a wet etching process to remove part of the microstructure from the second sidewall of the microstructure along the direction towards the first sidewall (i.e., the X' direction shown in the figure), with an etching depth of 5~20μm. In this embodiment, the etching depth is 5μm. At this point, the first passivation layer 41 forms a partially suspended structure.

[0093] It is understandable that after the wet etching process, the remaining microstructure serves as the first contact layer 211. The first contact layer 211, the oxide layer 11, and the first passivation layer 41 form a transversely open accommodating groove. The etching depth determines the size of the remaining microstructure and also determines the space used for secondary epitaxy (i.e., the size of the accommodating groove).

[0094] S5, a first confinement layer 212, an active layer 213, a second confinement layer 214 and a second contact layer 215 are sequentially stacked from the surface of the first contact layer 211 in a direction away from the first sidewall 501 to form an epitaxial structure layer 21.

[0095] Combination Figure 13 As shown, in this embodiment, a secondary epitaxial process is performed in the opposite direction to the removal of the microstructure, sequentially forming a first confinement layer 212, an active layer 213, a second confinement layer 214, and a second contact layer 215.

[0096] It should be noted that the sum of the dimensions of the first limiting layer 212, the active layer 213, the second limiting layer 214, and the second contact layer 215 along the width direction (i.e., the second direction X) is equal to the corrosion depth, that is, the edge of the second contact layer 215 away from the first limiting layer 212 is flush with the edge of the first passivation layer 41.

[0097] Furthermore, in this embodiment, the active layer adopts a quantum well design, and the emission wavelength matches the band edge design of the photonic crystal.

[0098] This embodiment will... Figure 12 The structure shown is placed in an MOCVD (Metal-Organic Chemical Vapor Deposition) device, and the first confinement layer 212, the active layer 213, the second confinement layer 214, and the second contact layer 215 are sequentially prepared by vapor phase epitaxial growth through thermal decomposition reaction.

[0099] It is understood that the first contact layer 211, the first confinement layer 212, the active layer 213, the second confinement layer 214, and the second contact layer 215 together constitute the light-emitting unit, which is the core component of the photonic crystal laser. Epitaxial fabrication processes are well known in the prior art, so their principles will not be described in detail here. Any known or unknown epitaxial fabrication process can be used without restriction.

[0100] S6, the first passivation layer 41 and the epitaxial structure layer 21 are etched sequentially to form a first through groove, and a second passivation layer 42 is prepared in the first through groove.

[0101] Combination Figure 14 As shown, the size w4 of the first through groove along the third direction Z is ≥ 5μm, which is also the size w4 of the second passivation layer 42 along the third direction Z is ≥ 5μm.

[0102] Furthermore, the dimension of the second passivation layer 42 in the thickness direction is greater than or equal to the dimension of the epitaxial structure layer 21 in the thickness direction, and the dimension of the second passivation layer 42 in the thickness direction is less than the distance between the surface of the first passivation layer 41 and the substrate layer 10.

[0103] It should be noted that in step S6, etching is performed at least down to the oxide layer 11, but not down to the silicon wafer 12. In this embodiment, the elongated device is isolated into independent devices through etching combined with passivation. Each independent device has the same structure.

[0104] S7, combined Figure 15 and Figure 16 As shown, a second electrode 32 is prepared next to the second contact layer, and the second electrode 32 contacts the second contact layer and achieves electrical connection;

[0105] S8, a wet etching process is used to remove part of the first passivation layer 41 to form a second through groove 70 that exposes the first contact layer 211 in the first passivation layer 41. The first electrode 31 is prepared in the second through groove 70 and the first electrode 31 is brought into contact with the exposed surface of the first contact layer to achieve electrical connection.

[0106] Combination Figure 17 and Figure 4As shown, a wet etching process is used to remove part of the first passivation layer 41 located above the substrate layer 10, so as to form a second through groove 70 exposing the first contact layer 211 within the first passivation layer 41.

[0107] In step S8, this disclosure removes a portion of the first passivation layer 41 on one side of the first sidewall to prepare the first electrode 31, while retaining a portion of the first passivation layer 41 between adjacent microstructures to achieve electrical isolation of the device.

[0108] It is understood that the first passivation layer 41 includes a portion disposed above the epitaxial structure layer 21 and a portion disposed above the oxide layer 11. Step S8 only processes the portion of the first passivation layer 41 disposed above the oxide layer 11, etching from the surface of the first passivation layer 41 (specifically the surface of the first passivation layer 41 away from the oxide layer 11) to the upper surface of the oxide layer 11, and exposing the sidewall of the first contact layer (i.e., the first sidewall 501).

[0109] The dimension of the second through groove 70 along the first direction Y is the maximum thickness of the first passivation layer, and the dimension of the second through groove 70 along the second direction X is less than the minimum distance between the sidewall of the first contact layer 211 and the edge of the first passivation layer.

[0110] It should be noted that in this embodiment, by retaining a portion of the first passivation layer 41 located next to the first contact layer, the remaining first passivation layer 41 isolates the first electrode 31 from the second electrode 32 of its adjacent laser.

[0111] S9, a photonic crystal is prepared in a portion of the first passivation layer 41 located above the epitaxial structure layer 21 to form a photonic crystal layer 22.

[0112] Combination Figure 5 As shown, the first passivation layer 41 located above the epitaxial structure layer 21 includes a first region 221 and a second region 222. In this embodiment, the projection of the second region 222 is circular, and the center of the circle is located above the active layer 213. The first passivation layer 41 within the second region 222 is etched or otherwise processed to obtain several periodically spaced photonic crystals. The first passivation layer 41 in the first region 221 and the photonic crystals in the second region 222 together constitute the photonic crystal layer 22. It should be noted that in this embodiment, the functional region of the photonic crystal layer 22 that performs functions such as optical path control is the second region 222.

[0113] Furthermore, in this embodiment, the photonic crystal layer 22 has a thickness dimension of 100~500nm, the photonic crystal dimension is 200nm, the spacing between the photonic crystals is 100~200nm, and the second region 222 has a dimension of 100~500μm.

[0114] It is understood that in this embodiment, the active region PN junction is placed laterally, and electrons are effectively injected into the active region by using lateral electric drive. The current direction is parallel to the substrate layer 10. The photonic crystal layer 22 is prepared by using the first passivation layer 41 located on the sidewall of the active layer. After electrons are injected into the active region, the emitted photons are coupled into the photonic crystal layer 22 and form standing wave oscillations through the photonic crystal band edge effect. Laser output is achieved along the direction perpendicular to the substrate layer 10, which greatly reduces the threshold current of the photonic crystal laser.

[0115] In this invention, the secondary epitaxial process is not affected by the photonic crystal fabrication process, which can greatly increase the electrical injection efficiency;

[0116] The device structure of the present invention is compact and the fabrication process is simple, making it easy to fabricate the first electrode 31 and the second electrode 32.

[0117] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0118] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A photonic crystal laser, characterized by, The photonic crystal laser comprises a substrate layer and a light-emitting unit on the substrate layer, wherein the light-emitting unit comprises an epitaxial structure layer and a photonic crystal layer on the epitaxial structure layer; The epitaxial structure layer comprises, in sequence from the direction parallel to the surface of the substrate layer, a first contact layer, a first confinement layer, an active layer, a second confinement layer and a second contact layer; Part of the photonic crystal layer is formed with periodically spaced photonic crystals.

2. The photonic crystal laser of claim 1, wherein, The photonic crystal laser further comprises a first electrode and a second electrode on the substrate layer, wherein the first electrode is formed beside the first contact layer, and the second electrode is formed beside the second contact layer; and / or The substrate layer comprises a silicon wafer and an oxide layer on the silicon wafer, and the oxide layer faces the light-emitting unit.

3. The photonic crystal laser of claim 2, wherein, The photonic crystal laser comprises a plurality of light-emitting units periodically arranged on the substrate layer, and a first passivation layer or a second passivation layer is arranged between adjacent light-emitting units.

4. A method of fabricating a photonic crystal laser, comprising: providing a substrate; forming a plurality of holes in the substrate; and filling the holes with a material having a refractive index greater than the substrate. The preparation method comprises: providing a composite substrate comprising a substrate layer and a semiconductor layer on the substrate layer; patterning and etching the semiconductor layer to form a plurality of microstructures periodically and spaced apart, wherein the microstructure comprises oppositely arranged first and second side walls; preparing a first passivation layer covering the upper surface and the first side wall of the microstructure; removing part of the microstructure from the second side wall of the microstructure in the direction towards the first side wall, and the remaining microstructure forms a first contact layer; sequentially stacking, from the surface of the first contact layer in the direction away from the first side wall, a first confinement layer, an active layer, a second confinement layer and a second contact layer to form an epitaxial structure layer; preparing a photonic crystal in part of the first passivation layer above the epitaxial structure layer.

5. The method of claim 4, wherein the method further comprises: The preparation method further comprises: sequentially etching the first passivation layer and the epitaxial structure layer to form a first through slot, and preparing a second passivation layer in the first through slot, wherein the size of the second passivation layer in the thickness direction is greater than or equal to the size of the epitaxial structure layer in the thickness direction, and the size of the second passivation layer in the thickness direction is less than the distance between the surface of the first passivation layer and the substrate layer.

6. The method of claim 4, wherein the photonic crystal laser is formed by a process comprising: The preparation method further comprises: removing part of the first passivation layer by a wet etching process to form a second through slot in the first passivation layer, which exposes the first contact layer. ​ 7. The method of claim 6, wherein the method further comprises: The preparation method further comprises: preparing a second electrode beside the second contact layer; preparing a first electrode in the second through slot and making the first electrode contact the exposed surface of the first contact layer.

8. The method of claim 4, wherein the photonic crystal laser is formed by a process comprising: Part of the microstructure is removed from the second side wall of the microstructure in the direction towards the first side wall by a wet etching process, and the etching depth is 5-20 μm. ​ 9. The method of claim 4, wherein the photonic crystal laser is formed by a process comprising: Patterning and etching the semiconductor layer to form a plurality of microstructures periodically and spaced apart, comprising: ​ growing a patterned mask layer on the surface of the semiconductor layer; etching part of the semiconductor layer by a first etching process.

10. The method of claim 4, wherein the photonic crystal laser is formed by a process comprising: The preparation method further comprises: preparing a composite substrate based on a Smart-Cut process. ​ 11. The method of claim 4, wherein the photonic crystal laser is formed by a method comprising: The size of the microstructure along the width direction is 200-500 μm, and the interval between two adjacent microstructures is greater than or equal to 30 μm; and / or, ​ The interval between two adjacent first passivation layers is 10-30 μm; and / or, The size of the photonic crystal layer along the thickness direction is 100-500 nm.

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