Semiconductor laser element and light emitting device

Abstract

The application relates to the technical field of semiconductor lasers, in particular to a semiconductor laser element and a light emitting device. The semiconductor laser element comprises an N-type semiconductor layer, a P-type semiconductor layer and an active layer; the P-type semiconductor layer comprises an electron blocking layer; the electron blocking layer comprises a P-type superlattice structure; the P-type superlattice structure comprises periodically and alternately stacked first sublayers and second sublayers; the material of the first sublayer comprises Al x1 In y1 Ga 1‑x1‑y1 N, the material of the second sublayer comprises Al x2 Ga 1‑x2 N, and 0 < x1 <= 1, 0 < x2 <= 1, x1!= x2, and 0 <= y1 <= 1. Through the above arrangement, the electro-optical conversion efficiency of the semiconductor laser element can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, and in particular to a semiconductor laser element and a light emitting device. Background Technology

[0002] Semiconductor lasers are light source devices widely used in communications, sensing, medical, and industrial processing. Their core working principle relies on the refractive index difference between the waveguide layer and the confinement layer in their internal structure to limit the lasing mode, thereby ensuring the stability of the laser's far-field spot characteristics and output power.

[0003] However, traditional semiconductor laser designs typically require high concentrations of electron / hole free carriers to achieve efficient carrier transport and low-resistance ohmic contacts. The significant difference in transport characteristics between electrons and holes, along with high operating currents, easily leads to non-uniform carrier injection, especially in short-wavelength lasers such as high-power blue lasers. In these lasers, high electron concentrations and fast migration rates cause electrons to leak into the P-type region, which cannot provide sufficient hole injection into the active region. This injection imbalance results in insufficient radiative recombination within the quantum well, limiting optical gain. Therefore, effectively improving the performance of semiconductor lasers remains a crucial challenge. Summary of the Invention

[0004] In view of at least one deficiency of the prior art, the purpose of this application is to provide a semiconductor laser element that can improve the electro-optical conversion efficiency of the semiconductor laser element.

[0005] In a first aspect, embodiments of this application provide a semiconductor laser element, the semiconductor laser element comprising at least an N-type semiconductor layer, a P-type semiconductor layer, and an active layer located between the N-type semiconductor layer and the P-type semiconductor layer; the P-type semiconductor layer includes an electron blocking layer; wherein the electron blocking layer includes a P-type superlattice structure; the P-type superlattice structure includes a periodically alternating first sublayer and a second sublayer; the material of the first sublayer includes Al. x1 In y1 Ga 1-x1-y1 N, the material of the second sublayer includes Al x2 Ga 1-x2 N, and 0 < x1 ≤ 1, 0 < x2 ≤ 1, x1 ≠ x2, 0 ≤ y1 ≤ 1.

[0006] Secondly, this application also provides a light emitting device, which employs a semiconductor laser element as described in the above embodiments.

[0007] Based on the above, compared with the prior art, the semiconductor laser element provided in this application can effectively improve the electro-optical conversion efficiency of the semiconductor laser element through the composite design of the electron blocking layer.

[0008] Other features and beneficial effects of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing this application. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 , Figure 2 , Figure 3 These are cross-sectional views of semiconductor laser elements with different modifications provided in the embodiments of this application; Figure 4 This is a schematic diagram of the electron blocking layer. Figure 5 This is the band structure diagram for a conventional conduction band; Figure 6 This is the energy band diagram of the conduction band of the structure in this embodiment; Figure 7 This is the band structure diagram of the valence band. Figure 8 This is the energy band diagram of the valence band structure in this embodiment; Figure 9 The graphs show the radiative recombination rates in the active layer of the conventional structure and the structure of this embodiment. Figure 10 This is a comparison chart of the luminous power of the conventional structure and the structure of this embodiment under different currents.

[0011] Figure label: 10. Substrate; 20. N-type semiconductor layer; 21. Lower cladding layer; 22. Lower waveguide layer; 30. Active layer; 40. P-type semiconductor layer; 41. Upper waveguide layer; 42. Upper cladding layer; 50. Electron blocking layer; 51. Al x3 53. GaN layer; 54. AlN layer; 55. P-type superlattice structure; 56. First sublayer; 57. Second sublayer; 68. First electrode; 69. Second electrode; 70. High reflectivity layer; 71. Antireflection layer. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings; the technical features designed in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0013] This application provides a semiconductor laser element, which includes at least an N-type semiconductor layer 20, a P-type semiconductor layer 40, and an active layer 30 located between the N-type semiconductor layer 20 and the P-type semiconductor layer 40; the P-type semiconductor layer 40 includes an electron blocking layer 50; wherein the electron blocking layer 50 includes a P-type superlattice structure 52; the P-type superlattice structure 52 includes a periodically alternating first sublayer 521 and a second sublayer 522; the material of the first sublayer 521 includes Al. x1 In y1 Ga 1-x1-y1 N, the material of the second sublayer 522 includes Al x2 Ga 1-x2 N, where 0 < x1 ≤ 1, 0 < x2 ≤ 1, x1 ≠ x2, and 0 ≤ y1 ≤ 1. By setting the above parameters, the electron blocking capability can be effectively enhanced, the carrier injection efficiency improved, the light absorption loss reduced, and the electro-optical conversion efficiency of the semiconductor laser element increased.

[0014] In one embodiment, in the P-type superlattice structure 52, the Mg doping concentration of the sublayer closest to the active layer 30 is less than the Mg doping concentration of the sublayer furthest from the active layer 30.

[0015] In one embodiment, the Mg doping concentration of the p-type superlattice structure 52 is between To ensure luminous efficiency.

[0016] In one embodiment, the Mg doping concentration of the sublayer closest to the active layer 30 is lower than that of the other sublayers; or, the Mg doping concentration of the P-type superlattice structure 52 gradually increases along the growth direction of the electron blocking layer 50. This configuration effectively suppresses the diffusion of Mg into the luminescent core region while improving hole injection efficiency.

[0017] In one embodiment, in the P-type superlattice structure 52, the number of alternating stacked periods of the first sublayer 521 and the second sublayer 522 is 3. 10, to alleviate stress and reduce defects.

[0018] In one embodiment, x1 > x2 to more effectively block electron leakage and improve lattice matching.

[0019] In one embodiment, x1-x2 ≥ 5% and x1-x2 ≤ 15%.

[0020] In one embodiment, the total thickness of the P-type superlattice structure 52 is less than or equal to 50 nm to effectively avoid suppressing hole injection.

[0021] In one embodiment, the thickness of the first sublayer 521 is between 1 and 10 nm, and / or the thickness of the second sublayer 522 is between 1 and 10 nm. This limited thickness range can effectively ensure lattice matching, alleviate stress accumulation, optimize carrier transport, and balance blocking and injection.

[0022] In one embodiment, it further includes at least one Al layer located between the active layer 30 and the P-type superlattice structure 52. x3 GaN layer 51, the Al x3 The Mg doping concentration in GaN layer 51 is less than or equal to , where 0≤x3≤1.

[0023] In one embodiment, the electron blocking layer 50 further includes layers located at the active layer 30 and Al. x3 AlN layer 53 between GaN layer 51.

[0024] In one embodiment, the Al x3 The Al composition concentration of the GaN layer 51 is constant along the growth direction of the electron blocking layer 50, or gradually increases or decreases; or, along the growth direction of the electron blocking layer 50, it first increases, then remains constant, and then decreases. The gradual Al composition design effectively alleviates the mismatch between the electron blocking layer and the waveguide / cladding layer, reducing stress accumulation and defect generation.

[0025] In one embodiment, x3 ≥ x1 and x3 ≥ x2 to better block electron spillover and diffusion of Mg components.

[0026] In one embodiment, the Al x3 The thickness of the GaN layer 51 is between 1 and 20 nm, avoiding Al x3 If the GaN layer is too thin or too thick, it will affect the electron blocking effect and alleviate the lattice mismatch.

[0027] In one embodiment, 0.1≤x2≤0.5 and 0≤y1≤0.1 are used to further block electron leakage and improve lattice matching effect.

[0028] In one embodiment, the absolute value of the difference in lattice constant between the first sublayer 521 and the second sublayer 522 is less than or equal to 0.5%, thereby effectively suppressing defect generation and stress accumulation.

[0029] In one embodiment, the bandgap width of the first sublayer 521 is greater than the bandgap width of the second sublayer 522 to enhance electron blocking capability and reduce hole injection resistance.

[0030] In one embodiment, the P-type semiconductor layer 40 further includes an upper waveguide layer 41 and an upper cladding layer 42, with the electron blocking layer 50 located between the upper waveguide layer 41 and the upper cladding layer 42.

[0031] In one embodiment, within the same period, the first sub-layer 521 is closer to the upper waveguide layer 41 than the second sub-layer 522.

[0032] This application also provides a light emitting device that employs a semiconductor laser element as described in any of the above embodiments to effectively improve the photoelectric performance of the light emitting device.

[0033] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application and through various specific implementation methods.

[0034] Example 1 Please see Figure 1 , Figure 1 This is a cross-sectional view of a semiconductor laser element provided in an embodiment of this application. To achieve at least one or more of the aforementioned advantages, an embodiment of this application provides a semiconductor laser element comprising at least an N-type semiconductor layer 20, a P-type semiconductor layer 40, and an active layer 30 located between the N-type semiconductor layer 20 and the P-type semiconductor layer 40.

[0035] The N-type semiconductor layer 20 is located on the substrate 10; the substrate 10 includes, but is not limited to, gallium nitride substrate 10, gallium arsenide substrate 10, sapphire substrate 10, silicon carbide substrate 10, etc. In this embodiment, the substrate 10 can be a growth substrate 10 or a support substrate 10; the substrate 10 is preferably a gallium nitride substrate 10.

[0036] An N-type semiconductor layer 20, an active layer 30, and a P-type semiconductor layer 40 are sequentially stacked on a substrate 10 to form an epitaxial stack. In this embodiment, the epitaxial stack can be formed on the substrate 10 using metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride vapor deposition (HVPE), physical vapor deposition (PVD), or ion plating. Preferably, the epitaxial stack is made of a nitride semiconductor material.

[0037] In this embodiment, the N-type semiconductor layer 20 may include, but is not limited to, a lower cladding layer 21, a lower waveguide layer 22, and a buffer layer (not shown in the figure), and the P-type semiconductor layer 40 may include, but is not limited to, an upper waveguide layer 41, an upper cladding layer 42, a resistive blocking layer, and a contact layer (not shown in the figure). The specific functional layers should be reasonably configured according to actual needs, and this embodiment does not impose any limitations. As an example, the N-type semiconductor layer 20 includes a lower cladding layer 21 and a lower waveguide layer 22, and the P-type semiconductor layer 40 includes an upper waveguide layer 41, an electron blocking layer 50, and an upper cladding layer 42.

[0038] The lower cladding layer 21 is made of N-type doped material to confine the light field in the direction towards the substrate 10; the upper cladding layer 42 is made of P-type doped material to confine the light field in the direction away from the substrate 10. The lower waveguide layer 22 is made of N-type doped material and the upper waveguide layer 41 is made of P-type doped material to increase the confinement of charge carriers, increase the distribution of charge carriers in the active layer 30, improve the light confinement factor, reduce the threshold current, and improve the luminous efficiency. Preferably, the lower waveguide layer 22, the upper waveguide layer 41, the upper cladding layer 42, and the lower cladding layer 21 are any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, and BN.

[0039] The active layer 30 can be a single quantum well layer composed of indium gallium nitride / gallium nitride, or a multiple quantum well layer composed of indium gallium nitride / gallium nitride grown in multiple alternating periods, to provide optical gain.

[0040] Please continue reading Figure 1 The semiconductor laser element also includes a first electrode 61 located on the side of the P-type semiconductor layer 40 away from the active layer 30 and a second electrode 62 located on the substrate 10 away from the N-type semiconductor layer 20. The first electrode 61 is electrically connected to the upper waveguide layer 41, and the second electrode 62 is electrically connected to the lower waveguide layer 22. At the same time, the first electrode 61 and the second electrode 62 are usually made of metal to be electrically connected to the outside world in order to control the conduction of the semiconductor laser.

[0041] Please see Figure 2 The N-type semiconductor layer 20, the P-type semiconductor layer 40, the active layer 30, and the substrate 10 form light-emitting or non-light-emitting cavity surfaces on opposite sides. The semiconductor laser element also includes a high-reflectivity coating 71 (HR) and an antireflection coating 72 (AR) respectively covering the two cavity surfaces. The high-reflectivity coating 71 is mainly used to reflect light within the laser element to form effective optical feedback, maintain laser oscillation, effectively increase the light intensity within the cavity, and improve output power. The antireflection coating 72 is mainly used to reduce surface reflection at the laser output end face, effectively reduce mode competition and power loss within the laser, improve the laser's output power, and also protect the end face from contamination and physical damage.

[0042] As an example, the material of the high-reflectivity layer 71 includes, but is not limited to, Ag, Au, Al, or other semiconductor materials such as GaAs, AlAs, etc., and can be a multilayer structure or a single-layer structure. The material of the antireflection layer 72 includes, but is not limited to, silicon dioxide, titanium dioxide, silicon nitride, magnesium fluoride, etc. In this embodiment, the high-reflectivity layer 71 is preferably a multi-period structure containing aluminum oxide and tantalum oxide, and the antireflection layer 72 is a single-period structure containing aluminum nitride and aluminum oxide materials.

[0043] Currently, semiconductor lasers typically require high concentrations of electron / hole free carriers to achieve efficient carrier transport and low-resistance ohmic contacts. However, the significant difference in transport characteristics between electrons and holes, along with high operating currents, leads to uneven carrier injection. Due to the high electron concentration and fast migration rate, electrons easily leak into the p-type semiconductor layer 40, which cannot provide sufficient hole injection into the active layer 30. This injection imbalance results in insufficient radiative recombination within the quantum well, limiting optical gain; simultaneously, electrons leaking into the p-type semiconductor layer 40 induce nonradiative recombination, thereby reducing the laser's photoelectric conversion efficiency (WPE). This problem is particularly pronounced in short-wavelength lasers such as high-power blue lasers.

[0044] Based on this, the electron blocking layer 50 designed in this embodiment can effectively suppress electron overflow to the P-type semiconductor layer 40 and reduce non-radiative recombination. In order to effectively improve the photoelectric conversion efficiency, conventional designs usually directly increase the Al composition of the electron blocking layer 50 to block more electrons. For example, the conventional electron blocking layer 50 generally uses a single layer of AlGaN with a high Al composition. However, although a high Al composition can block more electrons, it will make hole injection difficult, which will also lead to insufficient radiative recombination in the quantum well and limit the optical gain.

[0045] Therefore, this embodiment further designs the electron blocking layer 50, which can effectively solve the above problems and is more conducive to short-wavelength and high-power laser applications such as high-power blue lasers. Please continue reading. Figure 1 In this embodiment, the electron blocking layer 50 includes a P-type superlattice structure 52.

[0046] The P-type superlattice structure 52 includes a periodically alternating first sublayer 521 and a second sublayer 522; the material of the first sublayer 521 includes Al. x1 In y1 Ga 1-x1-y1 N, the material of the second sublayer 522 includes Al x2 Ga 1-x2N, where 0 < x1 ≤ 1, 0 < x2 ≤ 1, x1 ≠ x2, and 0 ≤ y1 ≤ 1. The superlattice structure design of the first sublayer 521 and the second sublayer 522 effectively increases the potential barrier, enhances electron blocking capability, reduces electron leakage, and thus reduces the recombination probability of holes and overflowing electrons, lowering non-radiative recombination loss and ensuring the efficiency of the luminescent core region. Simultaneously, it effectively solves the problem of difficult hole injection caused by high Al composition, improving hole injection efficiency and thereby enhancing the photoelectric conversion efficiency of the semiconductor laser device.

[0047] As an example, x1 > x2, meaning the Al concentration of the first sublayer 521 is greater than the Al concentration of the second sublayer 522. In specific implementation, this embodiment preferably has 0.1 ≤ x2 ≤ 0.5, for example, x2 can be 0.1, 0.2, 0.3, 0.4, or 0.5. The Al composition directly determines the band gap of the material (the higher the Al composition, the wider the band gap). By designing x1 > x2, the first sublayer 521 maintains a higher or equivalent Al composition, which allows the first sublayer 521 to form a wider band gap barrier to block electron leakage. Combined with the In composition introduced into the first sublayer 521, lattice matching can be controlled.

[0048] In one embodiment, x1-x2 ≥ 5% and x1-x2 ≤ 15%. That is, the difference between the proportion of Al component in the first sublayer 521 and the proportion of Al component in the second sublayer 522 is between 5% and 15%. This range of Al component difference keeps the Al components of the first and second sublayers close, with only slight fluctuations. This creates a suitable bandgap gradient to balance electron blocking and hole transport, and the small component difference effectively weakens interlayer lattice mismatch and alleviates interfacial stress.

[0049] In this embodiment, the preferred concentration of the In component introduced in the first sublayer 521 is in the range of 0 ≤ y1 ≤ 0.1, for example, y1 can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. By limiting this range, when the lattice mismatch between the first sublayer 521 and the second sublayer 522 in the superlattice is too large, an In component of less than or equal to 0.1 can be added to the first sublayer 521 to further compensate for the lattice shrinkage caused by the high Al component, regulate and achieve lattice matching, and at the same time avoid excessive lattice mismatch between the In component concentration and the second sublayer 522 due to excessively high In component concentration, thereby reducing interface stress and defects.

[0050] Preferably, in the P-type superlattice structure 52, the number of alternating stacked periods of the first sublayer 521 and the second sublayer 522 is 3. 10, for example, the number of cycles is 3, 4, 5, 6, 7, 8, 9, or 10. A single cycle's sublayers experience slight stress due to differences in Al / In composition. Alternating layers of multiple cycles can disperse this stress to various interfaces, thereby alleviating stress and reducing defects. Simultaneously, limiting the number of cycles to 3-10 layers effectively balances hole injection efficiency and electron blocking capability.

[0051] Preferably, within the same period, the first sublayer 521 is closer to the upper waveguide layer 41 than the second sublayer 522. Here, "within the same period" refers to a complete alternating stacked unit in the P-type superlattice structure 52, consisting of a first sublayer 521 and a second sublayer 522.

[0052] This layer sequence arrangement allows the first sublayer 521, with a high Al composition and narrow bandgap, to be located close to the upper waveguide layer 41, forming a high electron blocking barrier and reducing electron leakage to the upper cladding layer 42 on the active layer 30 side. At the same time, the second sublayer 522, with a low Al composition and wide bandgap, is arranged on the side away from the active layer 30, reducing the initial barrier for holes to enter the superlattice, promoting smooth hole transport, and ensuring carrier balance and radiative recombination efficiency within the active layer 30.

[0053] In one embodiment, the total thickness of the P-type superlattice structure 52 is less than or equal to 50 nm to effectively avoid difficulties in hole injection due to excessive total thickness and ensure effective hole injection.

[0054] Preferably, the thickness of the first sublayer 521 is between 1 and 10 nm, and / or the thickness of the second sublayer 522 is between 1 and 10 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm. The thicknesses of the first sublayer 521 and the second sublayer 522 at different locations can be the same or different, and can be reasonably set according to actual needs. This limited range of thicknesses can effectively ensure lattice matching, alleviate stress accumulation, optimize carrier transport, and balance blocking and injection.

[0055] In other embodiments, the absolute value of the difference in lattice constant between the first sublayer 521 and the second sublayer 522 is less than or equal to 0.5%. Specifically, the lattice constants of the first sublayer 521 and the second sublayer 522 in the P-type superlattice layer can be made close by simultaneously adjusting the Al and In compositions, thereby effectively suppressing defect generation and stress accumulation.

[0056] The bandgap width of the first sublayer 521 is greater than that of the second sublayer 522. By utilizing the wide bandgap of the first sublayer 521 to enhance electron blocking capability and the narrow bandgap of the second sublayer 522 to reduce hole injection resistance and carrier interface transport loss, combined with the superlattice's "periodic alternating stacking" characteristic and sublayer thickness design, it can be adapted to GaN-based lasers with different power requirements.

[0057] Building upon this, existing semiconductor laser designs suffer from significant optical absorption loss. Specifically, when the Mg component diffuses into the active layer 30, it forms "impurity energy levels" within the material. These levels absorb laser photon energy, causing photons to be "consumed" rather than emitted. Higher Mg doping concentrations result in higher impurity energy level densities and stronger optical absorption loss. Therefore, this embodiment further modulates the Mg composition of the p-type superlattice structure 52 to address the optical absorption loss problem in semiconductor lasers.

[0058] Specifically, in the P-type superlattice structure 52, the Mg doping concentration of the sublayer closest to the active layer 30 is less than the Mg doping concentration of the sublayer furthest from the active layer 30. Here, "the sublayer closest to the active layer 30" refers to the sublayer in the P-type superlattice structure 52 along its growth direction that is adjacent to the Al layer. x3 The first sublayer directly adjacent to GaN layer 51. "The sublayer furthest from the active layer 30" refers to the last sublayer of P-type superlattice structure 52 that is closest to the upper cladding layer 42 along the growth direction.

[0059] By designing the first sublayer with a low Mg doping concentration, the diffusion of Mg into the active region can be reduced, thereby reducing the light absorption loss near the active layer 30. At the same time, the design of the last sublayer with a high Mg doping concentration can reduce hole transport resistance and avoid insufficient hole supply.

[0060] Furthermore, in the P-type superlattice structure 52, the Mg doping concentration of the sublayer closest to the active layer 30 is lower than the Mg doping concentration of the remaining sublayers. Specifically, the Mg doping concentration of the first sublayer is the minimum value in the entire P-type superlattice structure 52; "remaining sublayers" refers to all subsequent sublayers arranged sequentially along the growth direction starting from the first sublayer (including another sublayer in the same period and all sublayers in subsequent periods), whose Mg doping concentration is greater than or equal to that of the first sublayer.

[0061] By employing a low-concentration design for the sublayer closest to the active layer 30, the diffusion of Mg into the luminescent core region is effectively suppressed. Meanwhile, the high-concentration design for all remaining sublayers, while resulting in slight absorption, ensures smooth hole transport and improves hole injection efficiency.

[0062] Furthermore, the Mg doping concentration of the P-type superlattice structure 52 gradually increases along the growth direction of the electron blocking layer 50. In this embodiment, the growth direction of the electron blocking layer 50 refers to the thickness direction from the active layer 30 towards the side closer to the P-type semiconductor layer 40. The gradual increase can be linear, nonlinear, or stepwise. That is, along the growth direction, the Mg doping concentration of each sublayer in the P-type superlattice structure 52 is greater than or equal to that of the previous sublayer. By gradually increasing the Mg doping concentration as described above, not only can Mg diffusion be suppressed to reduce light absorption loss, but it can also further ensure a continuous supply of holes and improve hole injection efficiency. That is, after holes enter the superlattice from the P-type cladding layer, they do not need to overcome the transport barrier of the "low-concentration sublayer" and can flow smoothly to the active layer 30 along the "high-concentration to low-concentration channel".

[0063] Preferably, the Mg doping concentration of the p-type superlattice structure 52 is between More preferably, between This range of values ​​provides a sufficient number of holes, ensuring efficient hole supply, while also preventing Mg doping oversaturation from forming clusters or lattice distortion, reducing defect-assisted nonradiative recombination centers, and ensuring luminescence efficiency. For example, in the p-type superlattice structure 52, the Mg doping concentration along the growth direction ranges from... linearly increase to .

[0064] In one embodiment, please refer to Figure 3 The electron blocking layer 50 further includes at least one Al layer located between the active layer 30 and the p-type superlattice structure 52. x3 GaN layer 51. Among them, Al x3 The GaN layer 51 is mainly used to block electron leakage and can be a single-layer or multi-layer structure. In this embodiment, Al x3 GaN layer 51 is an unintentionally doped Mg material that can block electron leakage.

[0065] Wherein, the Al x3 The Mg doping concentration in the GaN layer is less than or equal to , 0≤x3≤1. That is, when Al x3 The Mg doping concentration in GaN layer 51 does not exceed At that time, the Al x3 GaN layer 51 is an unintentionally doped Mg layer. By limiting the Al component and the low Mg doping concentration, it effectively prevents Mg from diffusing into the upper waveguide layer 41 and the active layer 30, thus preventing optical absorption loss and non-radiative recombination.

[0066] Preferably, the Al x3The thickness of the GaN layer 51 is between 1 and 20 nm, such as 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, etc. This thickness limitation can effectively avoid Al x3 If the GaN layer is too thin or too thick, it will affect the electron blocking effect and alleviate the lattice mismatch.

[0067] Preferably, the Al x3 The Al component concentration of GaN layer 51 is constant along the growth direction of electron blocking layer 50, or gradually increases, or shows a trend of first increasing, then remaining constant, and then decreasing along the growth direction of electron blocking layer 50.

[0068] In specific implementation, when Al x3 When GaN layer 51 is a structure with at least one layer, the first Al layer x3 The Al composition of GaN layer 51 can be designed to be constant. Furthermore, Al... x3 The Al composition in the GaN layer 51 can also be designed as a composition gradient (which may include linear gradient, gradient gradient, or other curved gradients, etc.). The composition gradient can be achieved by gradually decreasing or increasing along the growth direction of the electron blocking layer 50 (i.e., extending in a direction perpendicular to the surface of the substrate 10), or by first gradually increasing, then keeping it constant, and then decreasing. Compared to a design with a constant Al composition, this embodiment prefers a design with a gradient Al composition, which can alleviate the mismatch between the EBL and the waveguide layer and / or cladding layer, and reduce stress accumulation and defect generation.

[0069] like Figure 4 As shown, optionally, the electron blocking layer 50 further includes layers located between the active layer 30 and Al. x3 AlN layer 53 between GaN layer 51. AlN layer 53 can form an additional electron blocking barrier due to its wide bandgap characteristics to further reduce electron leakage, and can also alleviate interface lattice mismatch stress and reduce defects.

[0070] Furthermore, x3 ≥ x1 and x3 ≥ x2. That is, Al x3 The Al concentration in GaN layer 51 is not lower than the Al concentration in the first sublayer 521 and the second sublayer 522 of the p-type superlattice structure 52. This is achieved through higher Al concentrations. x3 The Al component concentration design of GaN layer 51 ensures that its band gap is greater than that of the first sublayer 521 and the second sublayer 522, forming a higher potential barrier, thereby better blocking electron overflow and Mg component diffusion.

[0071] To effectively illustrate the technical effects of the semiconductor laser element provided in the embodiments of the present invention, simulation experiments were conducted on conventional structures and the structure of this embodiment under the same conditions to obtain the following results: Figures 5-10The graph shown illustrates this. The conventional structure design uses an Al₂O₃ electron blocking layer with a thickness of only 10 nm. 0.4 GaN 0.6 In this embodiment, the structure is designed such that the electron blocking layer 50 includes Al. x3 GaN layer 51 and P-type superlattice layer, Al x3 The GaN layer 51 is an Al layer with a thickness of 10 nm. 0.4 GaN 0.6 The P-type superlattice layer includes five sets of first sublayers 521 and second sublayers 522 with a period of 5. The first sublayer 521 is an Al layer with a thickness of 2 nm. 0.3 In 0.02 Ga 0.68 N, the second sublayer 522 is an Al with a thickness of 2nm. 0.2 Ga 0.8 N; and in the P-type superlattice structure 52, the Mg doping concentration increases linearly from 4E18 to 8E18 along the growth direction.

[0072] Based on the above simulation experiments, Figure 5 This is the band structure diagram of the conduction band. Figure 6 The diagram shows the energy band structure of this embodiment. The blue curve represents the conduction band energy level of the electron blocking layer 50, and the green curve represents the quasi-Fermi level of electrons. The simulation shows that the electron blocking barrier increases from 306 meV to 357 meV, indicating an improvement in electron blocking capability. Figure 7 This is the band structure diagram of the valence band. Figure 8 The diagram shows the energy band structure of the valence band in this embodiment. The red curve represents the valence band energy level of the electron blocking layer 50, and the orange curve represents the quasi-Fermi level of the hole. The simulation shows that the hole injection barrier is reduced from 358 meV to 307 meV, indicating that the hole injection capability is improved and that the hole can tunnel into the quantum well. Figure 9 The graphs show the radiative recombination rates in the active layer 30 of the conventional structure and the structure of this embodiment. The simulation shows that the radiative recombination rate in the quantum well is increased after adopting the composite electron blocking layer 50 structure, which is attributed to the improvement of carrier injection efficiency. Figure 10 The diagram shows a comparison of the luminous power of the conventional structure and the structure of this embodiment under different currents. The experimental results show that the luminous power of the device is significantly improved after adopting the composite electron blocking layer 50 structure.

[0073] Based on the above composite design of electron blocking layer 50, defect generation and stress accumulation can be alleviated, and Mg can be prevented from diffusing to upper waveguide layer 41 and active layer 30, thereby reducing non-radiative recombination and light absorption loss. At the same time, the electron blocking capability can be further improved, the hole injection barrier can be reduced, and the hole has a certain probability of entering the quantum well through tunneling, effectively improving the hole injection efficiency and enhancing the luminous efficiency of semiconductor laser devices.

[0074] Example 2 This application also provides a light emitting device, which includes at least one semiconductor laser element as described in any of the above embodiments, which can effectively improve the light emission performance and can be applied to light emitting devices using semiconductor laser elements in various industries.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A semiconductor laser element, characterized in that, The semiconductor laser element includes: an N-type semiconductor layer, a P-type semiconductor layer, and an active layer located between the N-type semiconductor layer and the P-type semiconductor layer; the P-type semiconductor layer includes an electron blocking layer. The electron blocking layer comprises a P-type superlattice structure; the P-type superlattice structure comprises a periodically alternating first sublayer and a second sublayer; the material of the first sublayer comprises Al. x1 In y1 Ga 1-x1-y1 N, the material of the second sublayer includes Al x2 Ga 1-x2 N, and 0 < x1 ≤ 1, 0 < x2 ≤ 1, x1 ≠ x2, 0 ≤ y1 ≤ 1.

2. The semiconductor laser element according to claim 1, characterized in that: In the P-type superlattice structure, the Mg doping concentration of the sublayer closest to the active layer is less than the Mg doping concentration of the sublayer furthest from the active layer.

3. The semiconductor laser element according to claim 1, characterized in that: The Mg doping concentration of the P-type superlattice structure is between .

4. The semiconductor laser element according to claim 1, characterized in that: The Mg doping concentration of the sublayer closest to the active layer is less than that of the other sublayers; or, the Mg doping concentration of the P-type superlattice structure gradually increases along the growth direction of the electron blocking layer.

5. The semiconductor laser element according to claim 1, characterized in that: In the P-type superlattice structure, the number of periods in which the first sublayer and the second sublayer are alternately stacked is 3.

10.

6. The semiconductor laser element according to claim 1, characterized in that: x1 > x2.

7. The semiconductor laser element according to claim 6, characterized in that: x1-x2≥5% and x1-x2≤15%.

8. The semiconductor laser element according to claim 1, characterized in that: The total thickness of the P-type superlattice structure is less than or equal to 50 nm.

9. The semiconductor laser element according to claim 1, characterized in that: The thickness of the first sublayer is between 1 and 10 nm, and / or the thickness of the second sublayer is between 1 and 10 nm.

10. The semiconductor laser element according to claim 1, characterized in that: It also includes at least one Al layer located between the active layer and the P-type superlattice structure. x3 GaN layer, the Al x3 The Mg doping concentration in the GaN layer is less than or equal to , where 0≤x3≤1.

11. The semiconductor laser element according to claim 10, characterized in that: The electron blocking layer further includes layers located at the active layer and Al. x3 AlN layers between GaN layers.

12. The semiconductor laser element according to claim 10, characterized in that: The Al x3 The Al component concentration of the GaN layer is constant along the growth direction of the electron blocking layer, or gradually increases, or shows a trend of first increasing, then remaining constant, and then decreasing along the growth direction of the electron blocking layer.

13. The semiconductor laser element according to claim 10, characterized in that: x3≥x1 and x3≥x2.

14. The semiconductor laser element according to claim 10, characterized in that: The Al x3 The thickness of the GaN layer ranges from 1 to 20 nm.

15. The semiconductor laser element according to claim 1, characterized in that: 0.1≤x2≤0.5, 0≤y1≤0.

1.

16. The semiconductor laser element according to claim 1, characterized in that: The absolute value of the difference in lattice constant between the first sublayer and the second sublayer is less than or equal to 0.5%.

17. The semiconductor laser element according to claim 1, characterized in that: The bandgap width of the first sublayer is greater than the bandgap width of the second sublayer.

18. The semiconductor laser element according to claim 1, characterized in that: The P-type semiconductor layer further includes an upper waveguide layer and an upper cladding layer, with the electron blocking layer located between the upper waveguide layer and the upper cladding layer.

19. The semiconductor laser element according to claim 18, characterized in that: Within the same period, the first sub-layer is closer to the upper waveguide layer than the second sub-layer.

20. A light emitting device, characterized in that: The semiconductor laser element described in any one of claims 1-19 is used.

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