Semiconductor laser element and light emitting device

Abstract

The application provides a semiconductor laser element and a light-emitting device. The semiconductor laser element inserts a stress release layer between a first waveguide layer and an active layer, transitions the lattice constant from the substrate layer to the active layer well, reduces the lattice distortion rate, improves the interlayer lattice matching degree, provides a better growth environment for the active layer, reduces the micro-pit defects on the surface of the active layer, and improves the crystal quality of the active layer. Meanwhile, the peak intensity of In component in the stress release layer is less than the In component content in the first waveguide layer, so as to accurately control the laser wavelength and the carrier recombination position, reduce the electron overflow, improve the carrier recombination efficiency and the gain effect, avoid the generation of the double-peak phenomenon, and finally achieve the purpose of improving the light-emitting brightness.

Description

Technical Field

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

[0002] Gallium nitride (GaN) and its constituent group III nitrides are direct-transition wide-bandgap semiconductor materials with broad energy bands, making them ideal materials for fabricating lasers ranging from the ultraviolet to the green light band. GaN-based blue-green lasers offer advantages such as small size, high integration, high brightness, and high resolution. The distribution of the light field and the photon confinement capability are key factors affecting the performance of GaN-based blue-green lasers.

[0003] In laser products, to improve the confinement factor and reduce the problem of laser absorption due to doping within the waveguide layer, the structural design of laser products is simpler than that of traditional LED epitaxial structures. The waveguide layer of laser products can be used to confine the light field. When InGaN material is used for the waveguide layer, due to the significant difference in lattice between InGaN and GaN, interface defects are easily formed at the interface between the waveguide layer and the GaN layer. These interface defects affect the quality stability of the device. At the same time, lattice constant mismatch also brings about polarization field problems, which prevents charge carriers from recombining more effectively in the quantum well layer, seriously affecting the charge carrier recombination efficiency. In addition, the polarization field also causes the charge carrier recombination position to shift, resulting in a twin-peak phenomenon. All of these defects will have a significant negative impact on the performance of laser products.

[0004] Therefore, it is necessary to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] In view of the defects and deficiencies existing in the prior art, the purpose of this application is to provide a semiconductor laser element and light-emitting device to solve one or more of the above problems.

[0006] According to one aspect of this application, a semiconductor laser element is provided, comprising at least:

[0007] A semiconductor stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; the first semiconductor layer includes a first waveguide layer, and the second semiconductor layer includes a second waveguide layer, wherein the first waveguide layer and the second semiconductor layer are both located on the side of their respective semiconductor layers closer to the active layer; wherein...

[0008] The first waveguide layer and the active layer further include a stress relief layer, at least a portion of which contains an In component. The In component forms an ion intensity curve along the semiconductor stack growth direction, and the peak intensity of the In component in the stress relief layer in the ion intensity curve is less than the In component content in the first waveguide layer.

[0009] According to one aspect of this application, a semiconductor laser element is also provided, comprising at least:

[0010] A semiconductor stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; the first semiconductor layer includes a first waveguide layer, and the second semiconductor layer includes a second waveguide layer, wherein the first waveguide layer and the second semiconductor layer are both located on the side of their respective semiconductor layers closer to the active layer; wherein...

[0011] A stress relief layer is further included between the first waveguide layer and the active layer. The stress relief layer comprises a first sub-layer, a second sub-layer, and an intermediate layer located between the first sub-layer and the second sub-layer, all stacked sequentially. The intermediate layer contains an In component, and its thickness is between [missing information]. The thickness of the stress relief layer is between [a certain range]. between.

[0012] According to one aspect of this application, this application also provides a light-emitting device, which includes the semiconductor laser element described in the above technical solution.

[0013] Compared with the prior art, the semiconductor laser element and light-emitting device provided in this application have at least the following advantages:

[0014] In the technical solution of this application, by inserting a stress relief layer between the first waveguide layer and the active layer, the lattice constant can be better transitioned from the substrate layer to the active layer, reducing the lattice distortion rate, improving the interlayer lattice matching degree, providing a better growth environment for the active layer, reducing micro-pit defects on the surface of the active layer, and improving the crystal quality of the active layer; at the same time, the peak intensity of the In component in the stress relief layer is limited to be less than the In component content in the first waveguide layer, so as to precisely control the laser wavelength and carrier recombination position, reduce electron overflow, improve carrier recombination efficiency and gain effect, and avoid the generation of double peak phenomenon.

[0015] In addition, the light-emitting device provided in this application includes the semiconductor laser element provided in the above-mentioned technical solution. Therefore, the light-emitting device also has the above-mentioned good technical effects. Attached Figure Description

[0016] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0017] For convenience or clarity, the thickness and dimensions of each layer shown in the figure may be exaggerated, omitted, or drawn approximations. Additionally, the dimensions of the light-emitting devices do not perfectly reflect their actual dimensions.

[0018] Figure 1 The diagram shown is a cross-sectional view of a semiconductor laser element provided in an embodiment of this application.

[0019] Figure 2 The diagram shown is a cross-sectional structural schematic of a stress relief layer provided in an embodiment of this application.

[0020] Figure 3 The diagram shows the relationship between elemental ion intensity and depth over a portion of a semiconductor laser element provided in an embodiment of this application.

[0021] Figure 4 Displayed as Figure 3 A magnified view of a portion of the image.

[0022] List of reference numerals in the attached diagram:

[0023] 100 substrates

[0024] 210 Buffer Layer

[0025] 220 First coating layer

[0026] 230 Electronic Supply Layer

[0027] 240 First waveguide layer

[0028] 250 stress relief layer

[0029] 251 First Sublayer

[0030] 252 Second Sublayer

[0031] 253 Intermediate Layer

[0032] 300 Active Layer

[0033] 410 Second waveguide layer

[0034] 420 electron blocking layer

[0035] 430 Second Coating

[0036] 440 Ohm Contact Layer

[0037] 500 contact electrode

[0038] 600 insulation layer

[0039] 700 Second Electrode

[0040] 800 First Electrode Detailed Implementation

[0041] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0042] The composition and dopants of each layer in the semiconductor laser element described in this application can be analyzed using any suitable method, such as secondary ion mass spectrometry (SIMS). The thickness of each layer in the semiconductor laser element described in this application can be analyzed using any suitable method, such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM), in conjunction with, for example, the depth positions of each layer on a SIMS image.

[0043] In this application, unless otherwise specified, the term "peak shape" refers to a line profile containing two line segments with slopes of opposite signs, i.e., one line segment has a positive slope and the other has a negative slope. "Peak concentration" refers to the highest concentration value between the two line segments of the peak shape with slopes of opposite signs.

[0044] For ease of description, the growth direction of the semiconductor stack is defined as upward, and its opposite direction as downward.

[0045] like Figures 1-2As shown, this embodiment provides a semiconductor laser element, which includes at least a substrate 100 and a semiconductor stack located above the substrate 100. The semiconductor stack includes a first semiconductor layer, an active layer 300, and a second semiconductor layer stacked sequentially. In this embodiment, the first semiconductor layer is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer. The semiconductor laser element is an end-face emitting laser element having a light-emitting end face and a light-reflecting end face that intersect the main surfaces of the semiconductor layers such as the active layer 300. The semiconductor stack has a ridge with a mesa structure at the top, which is formed in the region of the second cladding layer 430 and above of the second semiconductor layer. The extension direction of the ridge is the laser propagation direction. An insulating layer 600 is provided on the side surface of the ridge and on the surface of the second semiconductor layer that is continuous from the side surface of the ridge.

[0046] The substrate 100 has an upper surface and a lower surface. A first electrode 800 is disposed on the lower surface, forming an electrical contact with a first semiconductor layer. Additionally, a contact electrode 500 is disposed on the upper surface of the ridge, forming an ohmic contact with a second semiconductor layer. The semiconductor laser element also includes a second electrode 700 disposed on the upper surface of the contact electrode 500, which is electrically connected to the contact electrode 500. The first electrode 800 and the second electrode 700 work together on the PN junction, releasing energy and generating photons through the recombination of electrons and holes. These photons are reflected and amplified by the resonant cavity to form a laser beam, thereby realizing the laser emission function of the laser diode.

[0047] See also Figures 1-2 The substrate 100 can be a growth substrate, including but not limited to nitride semiconductors, SiC, or high-resistivity substrates such as sapphire substrates. Substrates containing nitride semiconductors have higher thermal conductivity than sapphire, thus improving heat dissipation efficiency, reducing defects such as dislocations, and resulting in good crystallinity. In an optional embodiment, the substrate 100 can be a support substrate. The growth substrate originally used for epitaxially growing the semiconductor stack can be selectively removed according to application needs, and the semiconductor stack can then be transferred to the aforementioned support substrate. Further, the thickness of the substrate 100 ranges from 40 μm to 400 μm, for example, 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, and 300 μm.

[0048] See also Figures 1-2 The first semiconductor layer can be configured as a multilayer structure made of nitride semiconductors such as GaN, InGaN, and AlGaN. The first semiconductor layer includes a buffer layer 210, a first cladding layer 220, an electron providing layer 230, a first waveguide layer 240, and a stress relief layer 250 sequentially stacked on the substrate 100. The first semiconductor layer may also include other layers besides those mentioned above, and some layers may be omitted.

[0049] In one embodiment, a buffer layer 210 is formed on the substrate 100. The buffer layer 210 is located between the substrate 100 and the first cladding layer 220. The buffer layer 210 is an n-type material layer made of GaN-based III-V group nitride semiconductor or an undoped material layer. The material may be InGaN. It is used to adjust the substrate warpage to improve wavelength uniformity.

[0050] In one embodiment, a first cladding layer 220 is formed on the buffer layer 210. The first cladding layer 220 is located between the buffer layer 210 and the electron providing layer 230 or the first waveguide layer 240. Its material can be AlGaN. By adjusting the refractive index and thickness of the first cladding layer 220, the light field is confined, causing the light field to be mainly concentrated between the waveguide layers of the laser for gain, thereby improving the efficiency and performance of the laser. The first cladding layer 220 needs a certain thickness to effectively confine carriers and prevent electron overflow; typically, its thickness is between 100 nm and 500 nm.

[0051] In one embodiment, an electron-providing layer 230 is formed on the first cladding layer 220, and the electron-providing layer 230 is located between the first cladding layer 220 and the first waveguide layer 240. The n-type doping concentration of the electron-providing layer 230 is greater than or equal to 3 × 10⁻⁶. 18 atom / cm 3 This is to effectively increase the electron injection efficiency and improve the recombination efficiency of charge carriers in the active layer 300. The thickness of the electron providing layer 230 is less than or equal to 100 nm, specifically, the thickness of the electron providing layer 230 is between 10 nm and 100 nm, preferably between 10 nm and 50 nm, and the doping concentration is between 8 × 10⁻⁶. 18 atom / cm 3 ~1.5×10 19 atom / cm 3 The n-type impurity doping concentration of the electron providing layer 230 is typically greater than that of the first cladding layer 220. Understandably, doping within the waveguide layer leads to a decrease in gain, affecting carrier recombination efficiency and consequently, luminance. The insertion of the electron providing layer 230 effectively injects electrons from the first cladding layer 220 into the active layer 300, thereby accumulating sufficient non-equilibrium carrier concentration in the well layer of the active layer 300. This optimizes the quantity and distribution of carriers within the active layer 300, improving the quantum efficiency of the laser. Furthermore, the electron providing layer 230 also restricts the horizontal diffusion of electrons, reducing electron overflow and non-radiative recombination of carriers, ensuring they are primarily concentrated in the active region, thus improving the laser's efficiency.

[0052] In the above embodiment, the thickness of the electron-providing layer 230 is less than the thickness of the first waveguide layer 240. A relatively thinner electron-providing layer 230 can reduce defects generated during crystal growth within the layer, ensuring better optical confinement capability. It also provides a relatively flat surface as the growth base for the first waveguide layer 240, which is beneficial for improving the crystal quality of the first waveguide layer 240. The thickness of the electron-providing layer 230 is between 10nm and 30nm, for example, 10nm, 15nm, 20nm, 25nm, or 30nm. An excessively thick layer may introduce more defects or stress during subsequent material deposition, affecting the reliability and stability of the device. Conversely, an excessively thin layer cannot withstand stress or temperature changes in subsequent processes, leading to layer structure cracking or failure, and requiring higher precision in the doping process. Furthermore, the thickness of the electron-providing layer 230 is between 15nm and 25nm, for example, 20nm, to achieve a good balance between electron-providing capability and layer structure quality.

[0053] In the above embodiment, the electron providing layer 230 is a GaN material with a high Si doping concentration, which is greater than the doping concentration of the first cladding layer 220 and the first waveguide layer 240. By setting a higher Si doping concentration, the electron concentration is increased, ensuring sufficient carrier recombination in the active layer 300. For the relatively thin electron providing layer 230, the doping concentration of the electron providing layer 230 is also greater than the peak Si doping concentration in the stress relief layer 250. Specifically, the peak doping concentration of the stress relief layer 250 is less than or equal to 1.2 × 10⁻⁶. 19 atom / cm 3 The doping concentration of electron-providing layer 230 is between 8 × 10⁻⁶. 18 atom / cm 3 ~1.5×10 19 atom / cm 3 The doping concentration is between and greater than that of the stress relief layer 250 to provide sufficient electrons to the quantum well layer for effective recombination. Furthermore, along the growth direction of the semiconductor stack thickness, the Si element in the electron providing layer 230 is uniformly doped, and the initial doping concentration on its lower surface remains consistent with the doping concentration on its upper surface. This constant doping concentration simplifies the fabrication process and also keeps the electron concentration in the electron providing layer 230 stable, thereby improving the performance stability of the semiconductor laser device.

[0054] In the above embodiment, a stress relief layer 250 is further included between the first waveguide layer 240 and the active layer 300. The stress relief layer 250 includes a first sub-layer 251, a second sub-layer 252, and an intermediate layer 253 located between the first sub-layer 251 and the second sub-layer 252, which are stacked sequentially. The intermediate layer contains In composition. For example, the stress relief layer can be a GaN / InGaN / GaN multilayer structure. The stress relief layer 250 is doped with Si element. Along the growth direction of the semiconductor stack, the doping concentration of Si element is kept constant or gradually doped. The stress relief layer 250 has at least one doping peak concentration. The doping peak concentration is generated in any sub-layer of the stress relief layer 250, such as the first sub-layer 251, the second sub-layer 252, or the intermediate layer 253.

[0055] Experiments showed that, under the same semiconductor layer parameters, an electron-donating layer with a thickness of 100 nm and a doping concentration of 3 × 10⁻⁶ nm was successfully tested. 18 atom / cm 3 The comparison sample and the sample in this embodiment have an electron-providing layer thickness of 20 nm and a doping concentration of 8 × 10⁻⁶. 18 atom / cm 3 For the 455nm laser band, the confinement factor of the product is increased from 0.71 to 0.74, and the confinement capability of the laser is significantly improved.

[0056] In one embodiment, a first waveguide layer 240 is formed above the electron-providing layer 230, located between the electron-providing layer 230 and the stress-relieving layer 250. The first waveguide layer 240 can be made of InGaN. By doping InGaN with different proportions of Al, the refractive index and bandgap of the waveguide layer are adjusted, making the refractive index of the first waveguide layer 240 higher than that of the first cladding layer 220. This allows the optical signal to undergo total internal reflection at the interface between the waveguide layer and the cladding layer, thus confining its propagation within the waveguide layer and achieving effective optical gain. Simultaneously, the electron-providing layer 230 below the first waveguide layer 240 also helps to reduce electron spillover. The thickness of the first waveguide layer 240 is between 50 nm and 500 nm to achieve a balance between electron injection efficiency, refractive index, and layer structure strength. Further, the thickness of the first waveguide layer 240 is between 200 nm and 400 nm. In an optional embodiment, the In component in the first waveguide layer 240 gradually increases as it approaches the active layer 300, which can more effectively disperse the deformation of the trap layer, improve the crystal quality of the active layer 300, and increase the carrier recombination efficiency.

[0057] In the above embodiments, the Si doping concentration of the first waveguide layer 240 is less than the peak doping concentration of the stress relief layer 250, and the Si doping concentration of the first waveguide layer 240 is less than the doping concentration of the electron providing layer 230.

[0058] In one embodiment, a stress relief layer 250 is formed on the first waveguide layer 240, and the stress relief layer 250 is located between the first waveguide layer 240 and the active layer 300. Part of the stress relief layer 250 contains an In component, such as InGaN. See [link to relevant documentation]. Figure 3 The In component forms an ion intensity curve L along the semiconductor stack growth direction. The peak concentration of the ion intensity curve L is less than the maximum concentration of the In component in the first waveguide layer 240, so as to reduce lattice defects caused by lattice constant mismatch. The lattice constant is effectively transferred from the GaN substrate to the InGaN quantum well layer in the active layer 300, which significantly improves the interface flatness of the active layer 300 and provides a better growth environment for the quantum well layer, thereby improving the crystal quality of the active layer 300. The setting of the stress relief layer 250 can also effectively reduce the influence of the polarization field, increase the hole barrier, reduce the overflow probability and improve the carrier recombination efficiency, while reducing the generation of the peak wavelength twin peak phenomenon. By controlling the process parameters such as the material and structure of the stress relief layer 250, the quantum well lattice and polarization field are affected, thereby affecting the effective recombination probability and position of carriers, which can bring good effects on the optoelectronic performance and structural performance of semiconductor lasers. The In content within the In-containing portion of the stress relief layer 250 remains constant, or the In content varies uniformly or gradually from bottom to top within the stress relief layer 250. In an optional embodiment, the thickness of the stress relief layer 250 is between... Between, for example or Excessive thickness can affect the efficiency of carrier injection from the first waveguide layer 240 to the active layer 300, causing localized light absorption, a decrease in the gain coefficient, and a reduction in device brightness. Conversely, insufficient thickness will prevent effective lattice constant transition and thus hinder stress relief. Furthermore, the thickness of this stress relief layer 250 is between... Between these, a more balanced stress release effect can be achieved.

[0059] The stress relief layer 250 is doped with Si to reduce the polarization field of the active layer 300, thereby increasing the electron-hole recombination efficiency. The doping concentration is between 5 × 10⁻⁶. 18 atom / cm 3 ~1×10 19 atom / cm 3 Meanwhile, the Si doping concentration of the electron-providing layer 230 is greater than that of the stress-relieving layer 250, and its doping concentration is between 8 × 10⁻⁶. 18 atom / cm 3 ~5×10 19 atom / cm 3In this configuration, sufficient electron supply is ensured. In an optional embodiment, the Si doping concentration of the electron providing layer 230 is less than or equal to the doping concentration of the stress relief layer 250, and the doping concentration of the electron providing layer 230 is adjusted accordingly based on the crystal quality of the waveguide layer.

[0060] The stress relief layer 250 includes a first sub-layer 251, a second sub-layer 252, and an intermediate layer 253 located between the first sub-layer 251 and the second sub-layer 252, which are stacked sequentially. The first sub-layer 251 is in contact with the first waveguide layer 240, the second sub-layer 252 is in contact with the active layer 300, and the intermediate layer 253 contains In. The thickness of the intermediate layer 253 is between [missing information - likely a specific thickness]. In an optional embodiment, the first sub-layer 251 and the second sub-layer 252 comprise GaN, the intermediate layer 253 comprises InGaN, and the stress relief layer 250 forms a GaN / InGaN / GaN stacked structure. That is, the peak concentration of the ion intensity curve L caused by the In composition is generated at the intermediate layer 253, and the peak concentration of the In ion intensity curve of the InGaN material in the intermediate layer 253 is less than the maximum concentration of the In composition in the first waveguide layer 240. If the In composition content of the intermediate layer 253 is too high, it is easy to cause a double peak phenomenon, the laser wavelength half-width increases, the gain effect is poor, and the electron overflow reduces the recombination efficiency, affecting the brightness of the laser product. The In composition content of the intermediate layer 253 is relatively lower than the In ion peak intensity of the first waveguide layer 240, which can reduce lattice mismatch and reduce structural defects. The lower In composition content of the intermediate layer 253 also means that the lattice constant of this layer is closer to that of the second sub-layer 252 and the first well layer of the active layer 300, which is more conducive to achieving the stress relief effect from the N-type semiconductor layer to the active layer 300. The In component content of the intermediate layer 253 remains constant from bottom to top, or the In component in the intermediate layer 253 exhibits a uniform or gradient variation.

[0061] In one embodiment, the intermediate layer 253 may be composed of a GaN / InGaN superlattice structure, and the thickness of the intermediate layer 253 is between Alternatively, the stress relief layer 250 can also be composed of a GaN / InGaN superlattice structure.

[0062] In one embodiment, the thickness of the intermediate layer 253 is greater than the thickness of the first sub-layer 251, the thickness of the intermediate layer 253 is greater than the thickness of the second sub-layer 252, and the thickness of the first sub-layer 251 is less than the thickness of the second sub-layer 252, thereby facilitating stress release. Specifically, the thickness of the first sub-layer 251 is between... Between, for example, or The thickness of the second sublayer 252 is between Between, for example, or The thickness of the intermediate layer 253 is between Between, for example, or

[0063] In one embodiment, an active layer 300 is formed on top of a first semiconductor layer, located between a stress-relieving layer 250 and a second waveguide layer 410. The active layer 300 can be a multilayer structure made of nitride semiconductors such as GaN or InGaN. The active layer 300 has a single quantum well structure or a multiple quantum well structure. Compared to a single quantum well structure, a multiple quantum well structure is easier to achieve sufficient gain. When the active layer 300 includes a multiple quantum well structure, if well layers and barrier layers are alternately stacked, the first and last layers can be either well layers or barrier layers. Further, the multiple quantum well structure includes 2 to 3 pairs of alternating barrier layers and well layers, defining the thickness of the second sublayer 252 of the stress-relieving layer 250 as H2, and the thickness of the first barrier layer in the active layer 300 near the stress-relieving layer 250 as L1, where 0.8 ≤ H2 / L1 ≤ 1.2. That is, the thickness of the second sub-layer 252 is similar to the thickness of the first barrier layer, and the doping elements are similar. The second sub-layer 252 is inserted between the intermediate layer 253 and the active layer 300 in the form of a front barrier layer to relieve stress between the active layer 300 and the first semiconductor layer. As an example, the thickness of the first barrier layer can be... or The thickness of the second sublayer 252 can also be or The thickness of the first sublayer 251 is less than the thickness of the second sublayer 252 and the first barrier layer, for example, it can be... or In an optional implementation, the thickness of each barrier layer in the active layer 300 can be the same or different, and the thickness of each well layer can also be the same or different.

[0064] Furthermore, for a semiconductor laser element emitting blue-green light, the active layer 300 in contact with the stress relief layer 250 is a first well layer, and a first barrier layer, a second well layer, and a second barrier layer are sequentially stacked upwards from the first well layer. The potential well layer contains In... x Al y Ga 1-x-y N (0 < x < 1, 0 ≤ y < 1, 0 < x + y < 1), more preferably InGaN, the emission wavelength of the laser element can be controlled by adjusting the In content of the well layer to make it emit blue or green light, with an emission wavelength range of 430 nm to 550 nm.

[0065] Furthermore, for a semiconductor laser element emitting violet light, the active layer 300 in contact with the stress relief layer 250 is a first well layer, and a first barrier layer, a second well layer, a second barrier layer, a third well layer, and a third barrier layer are sequentially stacked upwards from the first well layer. The potential well layer contains In... x Al y Ga 1-x-y N (0 < x < 1, 0 ≤ y < 1, 0 < x + y < 1), more preferably InGaN, the emission wavelength of the laser element can be controlled by adjusting the In content of the well layer to make it emit violet light, with an emission wavelength range of 370 nm to 450 nm.

[0066] In one embodiment, a second semiconductor layer is formed on the active layer 300. The second semiconductor layer is a p-type semiconductor layer and can be formed using a single-layer or multi-layer structure formed from a nitride semiconductor layer. For example, the p-type nitride semiconductor layer included in the second semiconductor layer can be a layer formed from a nitride semiconductor containing p-type impurities such as Mg. The second semiconductor layer includes a second waveguide layer 410, an electron blocking layer 420, a second cladding layer 430, and an ohmic contact layer 440 stacked sequentially. The second semiconductor layer may also include other layers besides those described above; additionally, some layers may be omitted.

[0067] In one embodiment, a second waveguide layer 410 is formed on the active layer 300. The material of this second waveguide layer can be InGaN. The addition of In can buffer the deformation of the well layer. The maximum content of In in the second waveguide layer 410 is greater than the peak intensity of the In ion intensity curve L in the stress relief layer 250, thereby achieving a good transition from the lattice constant of the active layer 300 to the second semiconductor layer. The thickness of the second waveguide layer 410 is similar to that of the first waveguide layer 240, both ranging from 50 nm to 500 nm, to achieve a balance between carrier injection efficiency, refractive index, and layer structure strength. Further, the thickness of the second waveguide layer 410 is between 100 nm and 300 nm. In an optional embodiment, the In content in the second waveguide layer 410 gradually increases towards the active layer 300, which can more effectively disperse the deformation of the well layer, improve the crystal quality of the active layer 300, and increase the carrier recombination efficiency.

[0068] In one embodiment, an electron blocking layer 420 is formed on the second waveguide layer 410. This layer may be made of a wide bandgap material such as AlN or AlGaN to effectively block electron leakage from the second semiconductor layer to the active layer 300, while allowing holes to pass through. The second waveguide layer 410 and the electron blocking layer 420 work together in the laser to confine the optical field and charge carriers, which helps to more effectively recombine electrons and holes in the active region, thereby improving luminous efficiency.

[0069] In one embodiment, a second cladding layer 430 is formed on top of the electron blocking layer 420. The cladding layer 430 may be made of a wide bandgap material such as AlGaN. The second cladding layer 430 restricts light propagation within the waveguide layer by providing a lower refractive index than the second waveguide layer 410. The thickness of the second cladding layer 430 is between 100 nm and 500 nm to effectively restrict carrier diffusion, while avoiding excessive thickness that would increase series resistance.

[0070] In one embodiment, an ohmic contact layer 440 is formed on the second cladding layer 430. The material of the ohmic contact layer 440 may be GaN or InGaN, which matches the lattice constant of the second cladding layer 430. The high doping can improve the conductivity, thereby reducing the resistance to contact with the metal electrode, forming a good ohmic contact, and promoting uniform current injection.

[0071] In one embodiment of the present invention, the semiconductor laser element can be formed by etching a portion of the second semiconductor layer to create a ridge. The width of the ridge is adjusted to 1 μm to 5 μm. A contact electrode 500 is disposed on the upper surface of the ridge. Specifically, the main function of the contact electrode 500 is to improve the lateral extension capability and expand the area of ​​current application. The material of the contact electrode 500 can be a transparent conductive film such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or gallium oxide (GaO3), or it can be a metal such as nickel or gold. The contact electrode 500 is a transparent conductive film with a refractive index lower than that of the active layer 300. Further, an insulating layer 600 is formed on the side surface of the exposed ridge, the side surface of the contact electrode 500, and the surface of the second cladding layer 430 exposed by etching. The thickness of the insulating layer 600 is between 100 nm and 500 nm, and it can be formed from a single layer or multiple layers of materials such as oxides or nitrides of Si, Al, Zr, Ti, Nb, Ta, etc.

[0072] In one embodiment, a second electrode 700 is formed on the ridge and contacts the contact electrode 500 to be electrically connected to the second semiconductor layer. The thickness of the second electrode 700 is between 0.1 μm and 2 μm, and is generally only required to function as an electrode for a semiconductor laser element. Its material can be metals or alloys such as Ni, Rh, Cr, Au, W, Pt, Ti, and Al.

[0073] In one embodiment, a first electrode 800 is disposed on the lower surface of the substrate 100 and electrically connected to the first semiconductor layer. The material of the first electrode 800 includes any one or more combinations of Ni, Ti, Pd, Pt, Au, Al, TiN, ITO, and IGZO, but is not limited thereto.

[0074] like Figures 3-4The diagram shows the relationship between elemental concentration or ion intensity and depth for a portion of a semiconductor laser element provided in an embodiment of this application. This relationship can be obtained using a secondary ion mass spectrometer.

[0075] from Figure 3 It can be seen that the In component has an ion intensity curve L along the semiconductor stack growth direction. The ion intensity curve L includes a first part S1, a second part S2, a third part S3, and a fourth part S4 connected in sequence. Among them, the In component ion intensity of the first part S1 gradually increases in the semiconductor growth direction and reaches the maximum value at the connection with the second part S2. The second part S2 includes a first trough T1, a second trough T2, and an intermediate segment T3 located between the first trough T1 and the second trough T2. The ion intensity of the intermediate segment T3 is greater than the ion intensity of the first trough T1 and the second trough T2. The first trough T1 is connected to the first part S1, and the second trough T2 is connected to the third part S3. The In component ion intensity of the third part S3 has two significant peaks. The In component ion intensity of the fourth part S4 is at its maximum value at the initial intensity at the connection with the third part S3 and gradually decreases along the semiconductor growth direction.

[0076] In the above embodiment, the In component ion intensity of the second part S2 is less than the maximum In component ion intensity of the first part S1, and the In component ion intensity of the middle section T3 is less than the maximum ion intensity of the fourth part S4, to avoid carrier overflow caused by excessive In component content in the middle section. Specifically, for the second part S2, the In ion intensity of the middle section T3 is greater than the In ion intensity of the first trough T1 and the second trough T2. The semiconductor material corresponding to the middle section T3 can be, for example, InGaN, while the two troughs contain a small amount of In component or no In component. The semiconductor material corresponding to the two troughs can be, for example, GaN. It can be understood that the signal duration of the In component ion intensity corresponds to different semiconductor layer thicknesses to some extent. The layer thickness of the first part S1 is greater than the layer thickness corresponding to the second part S2; for the second part S2, the layer thickness of the middle section T3 is greater than the layer thickness corresponding to the first trough T1, and also greater than the layer thickness corresponding to the second trough T1.

[0077] In this embodiment, the first waveguide layer 240 corresponds to Figure 1 The first part S1 of the ion intensity curve L is shown. The stress relief layer 250 corresponds to the second part S2 of the ion intensity curve L. The active layer 300 corresponds to the third part S3 of the ion intensity curve L. The second waveguide layer 410 corresponds to the fourth part S4 of the ion intensity curve L.

[0078] In one embodiment, the In ion intensity of the stress relief layer 250 is lower than the maximum In ion intensity of the first waveguide layer 240 and the second waveguide layer 410, reducing lattice mismatch and structural defects. The lower In content also means that the lattice constant of this layer is closer to that of the first well layer of the active layer 300, which is more conducive to achieving stress relief from the N-type semiconductor layer to the active layer 300. The thickness of the first waveguide layer 240 corresponding to the first part S1 is between 50 nm and 500 nm to achieve a balance between electron injection efficiency, refractive index, and layer structure strength. Further, the thickness of the first waveguide layer 240 is between 200 nm and 400 nm.

[0079] In one embodiment, the ratio of the maximum In content of the stress-relieving layer 250 corresponding to the second part S2 to the maximum In content of the first waveguide layer 240 or the second waveguide layer 410 is between 1:8 and 1:4. The In content percentage of the first waveguide layer 240 and the second waveguide layer 410 is 4% to 8%, and the In content percentage of the second part S2, i.e., the stress-relieving layer 250, is 0.5% to 2%. Further, the In content percentage of the stress-relieving layer 250 is about 1%, and it is preferable that the In content in the stress-relieving layer 250 fluctuates within a range of 20% above and below 1%. Its lattice constant is between the first well layer in the active layer 300 and the substrate 100, realizing an effective lattice transition and good lattice matching, so that the interlayer stress can be released, reducing the surface micro-pits of the active layer 300, improving the interface flatness, improving the crystal growth quality of the active layer 300, and reducing the negative impact of the polarization field on the carrier recombination efficiency.

[0080] Through experiments, under the same conditions of other semiconductor layer parameters, when the In content percentage in the active layer is 10% and the maximum In content percentage of the first waveguide layer 240 and the second waveguide layer 410 is within the range of 4% to 8%, compared with the sample with the In content in the stress relief layer 250 of 8%, and the product with the In content in the stress relief layer 250 of 1% provided in this embodiment, the light confinement capabilities of the two are basically the same. However, the product with the In content of 1% has better active layer quality, smoother crystal surface growth, and improved light output brightness.

[0081] In an optional embodiment, the semiconductor layer corresponding to the middle segment T3 of the second part S2 is InGaN, and the semiconductor layers corresponding to the first trough T1 and the second trough T2 on both sides are GaN. That is, the In ion intensity curve of the second part S2 is formed by a three-layer stacked structure of GaN / InGaN / GaN. Specifically, the middle segment T3 corresponds to the middle layer 253 in the stress relief layer 250, and the first trough T1 and the second trough T2 correspond to the first sublayer 251 and the second sublayer 252 in the stress relief layer 250, respectively. The thickness of the first sublayer 251 is between... Between, preferably The thickness of the second sublayer 252 is between Between, preferably The thickness of the intermediate layer 253 is between Between, preferably The overall thickness of the stress relief layer 250 corresponding to the second part S2 is between... Between, preferably This achieves a more balanced stress relief effect. In an optional embodiment, the intermediate layer 253 may be composed of a GaN / InGaN superlattice structure, or the stress relief layer 250 may also be composed of a GaN / InGaN superlattice structure, which will not be elaborated here.

[0082] Furthermore, the In content percentage in the semiconductor layer corresponding to the third part S3, i.e., the quantum well layer, is between 10% and 15%. The In content in the stress relief layer 250 should not be too high. When the In content is high, for example, exceeding 2%, the stress relief layer 250, to some extent, plays a similar role to the well layer in the active layer 300, easily causing carrier overflow and recombination position shift. Carriers originally recombinating in the well layer shift towards the stress relief layer 250, causing double-peak or multi-peak problems, increasing the laser wavelength half-width, broadening the beam shape, and resulting in a loss of brightness in the active layer 300. Similarly, the In content in the stress relief layer 250 should not be too low either; for example, below 0.5%, it cannot effectively reduce lattice mismatch, nor can it effectively improve the surface flatness of the active layer 300.

[0083] Understandably, for semiconductor lasers of other wavelengths, the emission wavelength can be adjusted by changing the In content in the active layer 300, thereby achieving the emission of light of different colors. Taking a green semiconductor laser element as an example, the green light wavelength is longer than the blue light wavelength, and the In content in its active layer 300 is also relatively high. In order to confine the light between the waveguide layers, the difference in refractive index between the waveguide layer and the cladding layer should also be large. Therefore, the In content in the waveguide layer is also higher than that in blue light devices, and the In content in the stress relief layer of green light devices is also correspondingly higher, so as to effectively achieve lattice constant matching between the first semiconductor layer and the active layer 300. For green semiconductor lasers, the In ion intensity in the stress relief layer 250 is also lower than the In composition content in the first waveguide layer 240 and the second waveguide layer 410. Furthermore, the stress relief layer structure of the green semiconductor laser may also include a first sub-layer 251, a second sub-layer 252, and an intermediate layer 253 located between the first sub-layer 251 and the second sub-layer 252, which are stacked in sequence. The similarity between the structure and parameters of the green semiconductor laser and the blue semiconductor laser described above will not be repeated here.

[0084] See also Figures 3-4 As can be seen, Si has a concentration curve n along the semiconductor stack growth direction. This concentration curve n includes a first segment D1, a second segment D2, and a third segment D3 connected sequentially. The first segment D1 corresponds to the region of the first semiconductor layer far from the active layer 300, and the third segment D3 corresponds to the region of the first semiconductor layer close to the active layer 300. The concentration value of the second segment D2 is lower than that of the first segment D1. Si has a peak concentration at the third segment D3, and the concentration of the first segment D1 is greater than this peak concentration. The first segment D1 has a first concentration, the second segment D2 has a second concentration, and the third segment D3 has a peak concentration. The first concentration of the first segment D1 is greater than the peak concentration of the third segment D3, and the first concentration is between 8 × 10⁻⁶. 18 atom / cm 3 ~1.5×10 19 atom / cm 3 This is used to effectively increase electron injection efficiency and improve the quantum efficiency of lasers.

[0085] In one embodiment, the peak concentration of D3 in the third segment is less than or equal to 1.2 × 10⁻⁶. 19 atom / cm 3 The third segment D3 is a semiconductor layer close to the active layer 300. Limiting its peak concentration can prevent excessively high doping concentration from causing defects in the crystal and reduce polarization electric field phenomena in the stress relief layer 250. Understandably, by optimizing the distribution of Si elements, the third segment D3 may have more than one peak concentration to optimize the performance of the semiconductor laser device. In an optional embodiment, when the third segment D3 corresponds to multiple stacked structures composed of different materials, such as a GaN / InGaN / GaN multilayer structure, the doping peak concentration can be generated in any semiconductor sublayer corresponding to the third segment D3, and the first concentration of the first segment D1 is greater than the highest peak concentration of the third segment D3.

[0086] In this embodiment, the electron providing layer 230 corresponds to Figure 2 The first segment D1 of the concentration curve n is shown. The first waveguide layer 240 corresponds to the second segment D2 of the concentration curve n, and the stress relief layer 250 corresponds to the third segment D3 of the concentration curve n.

[0087] In the above embodiments, the first segment D1 can be a highly Si-doped AlGaN material with a concentration greater than 3 × 10⁻⁶. 18 atom / cm 3 Specifically, the doping concentration is between 3 × 10⁻⁶. 18 atom / cm 3 ~1.5×10 19 atom / cm 3Between these two segments, a highly doped first segment D1 is inserted before the second segment D2 to provide sufficient electron concentration, improve electron-hole recombination efficiency, and thus enhance luminescence brightness. Furthermore, the doping concentration of the first segment D1 is between 1 × 10⁻⁶. 19 atom / cm 3 ~1.2×10 19 atom / cm 3 The concentration of D2 in the second segment is between 5 × 10⁻⁶. 17 atom / cm 3 ~5×10 18 atom / cm 3 Between these values, the peak concentration of D3 in the third segment is between 1×10⁻⁶. 18 atom / cm 3 ~5×10 19 atom / cm 3 The doping concentration is between, but less than, that of the first segment D1. The stress relief layer 250 corresponding to the third segment D3 is relatively highly doped to reduce the influence of the polarization field on the carrier recombination efficiency in the active layer 300. Furthermore, the peak concentration of the third segment D3 is less than or equal to 1.2 × 10⁻⁶. 19 atom / cm 3 .

[0088] In one embodiment, the third segment D3, i.e., the stress relief layer 250, is relatively highly doped to suppress the polarization field and improve carrier recombination efficiency, for example, by Si doping. However, highly doped semiconductor layers can cause severe light absorption, reducing the gain effect and leading to a deterioration in the performance of the semiconductor laser device. Therefore, the thickness of the stress relief layer 250 should not be too large. It is understood that the duration of the Si concentration signal corresponds to different semiconductor layer thicknesses to some extent, and the thickness of the third segment D3, i.e., the stress relief layer 250, should be... Preferably, the stress relief layer 250 has a thickness between

[0089] In the above embodiment, the Si concentration of the semiconductor layer corresponding to the first segment D1, i.e., the electron-providing layer 230, is greater than the peak concentration in the third segment D3, i.e., the stress-relieving layer 250. Furthermore, Si is uniformly doped along the semiconductor stack growth direction, maintaining a consistent doping concentration from the initial doping concentration on the lower surface to the upper surface. This constant doping concentration simplifies the fabrication process and ensures stable electron concentration in the electron-providing layer 230, thereby improving the performance stability of the semiconductor laser element. The insertion of the electron-providing layer 230 optimizes the number and distribution of charge carriers within the active layer 300, improving the quantum efficiency of the laser. Its in-layer doping concentration is between 8 × 10⁻⁶. 18 atom / cm 3 ~1.5×10 19atom / cm 3 Between these layers, sufficient electrons are provided to the quantum well layer for effective recombination. Alternatively, the doping concentration of the first segment D1 can be uniformly graded doped or gradient graded doped.

[0090] In one embodiment, the thickness of the electron-providing layer 230 is less than the thickness of the first waveguide layer 240. A relatively thin electron-providing layer 230 can reduce defects generated during crystal growth within the layer, ensuring a higher gain coefficient. It also provides a relatively flat surface as the growth base for the first waveguide layer 240, which is beneficial for improving the crystal quality of the first waveguide layer 240. The thickness of the electron-providing layer 230 is 10 nm to 50 nm. Further, the thickness of the electron-providing layer 230 is between 15 nm and 25 nm, for example, 20 nm, to achieve a good balance between electron-providing capability and layer structure quality.

[0091] This embodiment also provides a light-emitting device, which includes any of the semiconductor laser elements in the above embodiments, and therefore the light-emitting device also has the above-mentioned excellent effects.

[0092] In summary, the semiconductor laser element and light-emitting device provided in this application effectively overcome the various shortcomings of the prior art and have high industrial application value.

[0093] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A semiconductor laser element, characterized in that, At least including: A semiconductor stack, the semiconductor stack comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially; The first semiconductor layer includes a first waveguide layer, and the second semiconductor layer includes a second waveguide layer. Both the first and second waveguide layers are located on the side of their respective semiconductor layers closest to the active layer. The first waveguide layer and the active layer further include a stress relief layer, at least a portion of which contains an In component. The In component forms an ion intensity curve along the semiconductor stack growth direction, and the peak intensity of the In component in the stress relief layer in the ion intensity curve is less than the maximum content of the In component in the first waveguide layer.

2. The semiconductor laser element according to claim 1, characterized in that, The peak intensity of the ion intensity curve of the In component in the stress relief layer is less than that of the In component in the second waveguide layer.

3. The semiconductor laser element according to claim 1, characterized in that, The ion intensity curve of the stress relief layer has a first trough, a second trough, and an intermediate segment between the first trough and the second trough, wherein, The In component ion intensity in the intermediate section is less than the In component content in the first waveguide layer and / or the second waveguide layer.

4. The semiconductor laser element according to claim 1, characterized in that, The stress relief layer includes a first sublayer, a second sublayer, and an intermediate layer located between the first sublayer and the second sublayer, which are stacked sequentially; wherein the first sublayer and the second sublayer include GaN, and the intermediate layer contains an In component and has an intensity peak of the ion intensity curve of the In component.

5. A semiconductor laser element, characterized in that, At least including: A semiconductor stack, the semiconductor stack comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially; The first semiconductor layer includes a first waveguide layer, and the second semiconductor layer includes a second waveguide layer. Both the first and second waveguide layers are located on the side of their respective semiconductor layers closest to the active layer. The first waveguide layer and the active layer further include a stress relief layer. The stress relief layer includes a first sub-layer, a second sub-layer, and an intermediate layer located between the first sub-layer and the second sub-layer. The intermediate layer contains an In component. The peak concentration of the In ion intensity curve of the intermediate layer is less than the maximum content of the In component in the first waveguide layer. The thickness of the intermediate layer is between 50 Å and 150 Å. The thickness of the stress relief layer is between 100 Å and 300 Å.

6. The semiconductor laser element according to claim 4 or 5, characterized in that, The first sublayer and the second sublayer comprise GaN; the intermediate layer comprises InGaN.

7. The semiconductor laser element according to claim 4 or 5, characterized in that, The thickness of the intermediate layer is greater than the thickness of the first sub-layer or the second sub-layer.

8. The semiconductor laser element according to claim 4 or 5, characterized in that, The thickness of the first sublayer is between 20 Å and 70 Å; the thickness of the second sublayer is between 20 Å and 70 Å.

9. The semiconductor laser element according to claim 4 or 5, characterized in that, The In component content of the intermediate layer is between 0.5% and 2.0%.

10. The semiconductor laser element according to claim 4 or 5, characterized in that, The percentage of In component in the first waveguide layer is between 4.0% and 8.0%.

11. The semiconductor laser element according to claim 4 or 5, characterized in that, The ratio of the maximum In content of the intermediate layer to the maximum In content of the first or second waveguide layer is between 1:8 and 1:

4.

12. The semiconductor laser element according to claim 4 or 5, characterized in that, The active layer is a multiple quantum well structure, which includes 2 to 3 pairs of alternating barrier layers and well layers; the thickness of the second sub-layer is H2, and the thickness of the barrier layer near the second sub-layer is L1, wherein 0.8≤H2:L1≤1.

2.

13. The semiconductor laser element according to claim 1 or 5, characterized in that, The first semiconductor layer further includes a first cladding layer and an electron providing layer, wherein the electron providing layer is located between the first cladding layer and the first waveguide layer.

14. The semiconductor laser element according to claim 13, characterized in that, The thickness of the electron-providing layer is less than or equal to 100 nm.

15. The semiconductor laser element according to claim 1 or 5, characterized in that, The laser element emits light at a wavelength of 430nm to 550nm.

16. A light-emitting device, characterized in that, The light-emitting device includes the semiconductor laser element as described in any one of claims 1 to 15.

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