Laser epitaxial structure with transition compensation structure and laser

Abstract

The application discloses a laser epitaxial structure with a transition compensation structure and a laser. The laser epitaxial structure with the transition compensation structure comprises an n-type confinement layer, a first waveguide layer, a quantum well active layer, a second waveguide layer, a p-type electron blocking layer, a p-type confinement layer and a p-type ohmic contact layer arranged in sequence along a specified direction, and a p-type transition compensation layer arranged between the second waveguide layer and the p-type electron blocking layer. The concentration of acceptor impurities in the p-type transition compensation layer is higher than that in the p-type electron blocking layer. The potential barrier of the p-type transition compensation layer is higher than that of the second waveguide layer and lower than that of the p-type electron blocking layer. The application greatly strengthens the probability of the combination of electrons and holes in the quantum well active layer, improves the radiative recombination, improves the crystal quality and achieves the effect of increasing the service life of the laser.

Description

Technical Field

[0001] This invention relates in particular to a laser epitaxial structure with a transition compensation structure and a laser, belonging to the field of semiconductor technology. Background Technology

[0002] Gallium nitride (GaN) lasers are a current research hotspot, attracting widespread attention and application as a next-generation optoelectronic device in fields such as novel displays, optical communications, and optical lighting. GaN lasers require high current densities to operate, placing extremely high demands on the crystal quality of the materials. Unlike other GaN devices, such as LEDs, which are not highly sensitive to crystal quality, poor material quality directly impacts the lifespan and output power of lasers. Existing epitaxial structures and methods still fall far short of the lifespan and performance of other lasers (GaAs-based).

[0003] Because the operating current of the laser is in kA / cm 2 The current density in the device is extremely high, with a large number of electrons forming a high-speed, highly concentrated flow towards the light-emitting active region of the InGaN / GaN quantum well structure and recombinating with holes to produce lasing. To prevent electron leakage, an electron blocking layer is usually grown behind the upper waveguide layer to block electrons from crossing the light-emitting active region of the quantum well and prevent them from entering the main P-type region. However, this also has adverse effects. For example, if the lattice mismatch between the upper waveguide layer and the p-AlGaN electron blocking layer is too large, it can easily cause dislocations and stress, which in turn can lead to a decrease in crystal quality and the formation of cracks in the material. Summary of the Invention

[0004] The main objective of this invention is to provide a laser epitaxial structure and a laser with a transition compensation structure, thereby overcoming the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0006] The present invention provides a laser epitaxial structure with a transition compensation structure, comprising an n-type confinement layer, a first waveguide layer, a quantum well active layer, a second waveguide layer, a p-type electron blocking layer, a p-type confinement layer, and a p-type ohmic contact layer arranged sequentially along a specified direction. The epitaxial structure further includes a p-type transition compensation layer disposed between the second waveguide layer and the p-type electron blocking layer. The barrier of the p-type transition compensation layer is higher than the barrier of the second waveguide layer but lower than the barrier of the p-type electron blocking layer.

[0007] Furthermore, the acceptor impurity concentration in the p-type transition compensation layer is higher than that in the p-type electron blocking layer.

[0008] Furthermore, the acceptor impurity concentration in the p-type transition compensation layer is 5-10 times that in the p-type electron blocking layer.

[0009] Furthermore, the acceptor impurity in the p-type transition compensation layer and the p-type electron blocking layer is Mg, and the Mg doping concentration in the p-type transition compensation layer is 1E20-5E20cm- 3 The Mg doping concentration in the p-type electron blocking layer is 1E19-5E19 cm⁻¹ -3 If the concentration of acceptor impurities in the p-type transition compensation layer is too low, it will not have a compensation effect, while if the concentration is too high, the acceptor impurities will diffuse into the light-emitting active region, affecting it and reducing the luminous efficiency.

[0010] Furthermore, the quantum well active layer, the second waveguide layer, and the p-type transition compensation layer are all formed of group III nitrides containing In, and the In content in the quantum well active layer is greater than the In content in the second waveguide layer, which in turn is greater than the In content in the p-type transition compensation layer.

[0011] Alternatively, both the quantum well active layer and the second waveguide layer are formed of group III nitrides containing In, the p-type transition compensation layer does not contain In, and the In content in the quantum well active layer is greater than the In content in the second waveguide layer.

[0012] Furthermore, the In content in the p-type transition compensation layer is 1.5-3 at.%, the In content in the quantum well active layer is 15-25 at.%, and the In content in the second waveguide layer is 3-6 at.%.

[0013] Furthermore, the p-type transition compensation layer includes a p-type InGaN / GaN superlattice structure layer, a p-type InGaN layer, or a p-type GaN layer.

[0014] Furthermore, the thickness of the p-type transition compensation layer is 5-50 nm.

[0015] Furthermore, the p-type InGaN / GaN superlattice structure layer comprises at least one periodic InGaN / GaN superlattice, wherein the thickness of the InGaN layer in the InGaN / GaN superlattice is 1-5 nm and the thickness of the GaN layer is 1-5 nm.

[0016] Furthermore, the active layer of the quantum well includes an InGaN / GaN quantum well, and the materials of the first waveguide layer and the second waveguide layer both include InGaN.

[0017] Furthermore, both the p-type electron blocking layer and the p-type confinement layer are made of AlGaN.

[0018] Furthermore, the n-type confinement layer is disposed on the n-type substrate.

[0019] Furthermore, the n-type substrate includes an n-type GaN substrate or an n-type GaN template formed from a heterogeneous substrate.

[0020] Furthermore, the laser epitaxial structure with transition compensation includes: an n-AlGaN confinement layer, a first InGaN waveguide layer, an InGaN / GaN quantum well active layer, a second InGaN waveguide layer, a p-type transition compensation layer, a p-AlGaN electron blocking layer, a p-AlGaN confinement layer, and a p-GaN ohmic contact layer arranged sequentially along a specified direction. The p-type transition compensation layer includes a p-type InGaN / GaN superlattice structure layer, a p-type InGaN layer, or a p-type GaN layer.

[0021] In another aspect, the present invention provides a laser, including the laser epitaxial structure having the aforementioned transition compensation structure.

[0022] Compared with the prior art, the advantages of the present invention include:

[0023] 1) The present invention provides a laser epitaxial structure that alleviates the problems of lattice mismatch between the second waveguide layer and the p-type electron blocking layer and the generation of tensile stress cracks in traditional laser epitaxial structures;

[0024] 2) The laser epitaxial structure provided by the present invention has the activation effect of p-type Mg under In composition, which can increase the Mg concentration of p-AlGaN electron blocking layer, thereby compensating for holes. This overcomes the problem of low Mg concentration and slow hole concentration increase in p-type doping when there is only p-type electron blocking layer. In this way, the probability of electron and hole recombination in quantum well active layer is greatly enhanced, radiative recombination is improved, crystal quality is improved and the laser lifetime is increased.

[0025] 3) The laser formed by the laser epitaxial structure provided by this invention has higher optical power output efficiency;

[0026] 4) The laser epitaxial structure provided by this invention has a simple fabrication process with good repeatability, which is beneficial for reducing the threshold voltage of GaN-based lasers, improving the luminous efficiency of lasers, improving crystal quality and increasing the lifespan of lasers, and is more suitable for industrial production. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the epitaxial structure of a conventional GaN-based laser in the prior art;

[0028] Figure 2This is a schematic diagram of the epitaxial structure of a traditional GaN-based laser in the prior art;

[0029] Figure 3 This is a schematic diagram of the epitaxial structure of a GaN-based laser in a typical embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the epitaxial structure of a GaN-based laser in a typical embodiment of the present invention. Detailed Implementation

[0031] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate the technical solution, its implementation process, and its principles in conjunction with the accompanying drawings and specific embodiments.

[0032] This invention provides a laser epitaxial structure that addresses the problems of strong N-type region and weak P-type region in existing lasers, as well as the large lattice mismatch between the second waveguide layer and the p-type electron blocking layer. A p-type transition compensation layer is provided between the second waveguide layer and the p-type electron blocking layer. The main function of the p-type transition compensation layer is to mitigate the lattice change between the second waveguide layer and the high Al content p-type electron blocking layer, thus acting as a transition layer. Simultaneously, the p-type Mg in this p-type transition compensation layer has an activation effect under In composition, which can consequently increase the Mg concentration of the p-type electron blocking layer at this point, thereby compensating for holes.

[0033] Please see Figure 3 An epitaxial structure for a laser with a transition compensation structure includes, sequentially stacked along a specified direction, an n-type substrate (also referred to as an n-type bottom layer) 11, an n-type confinement layer (also referred to as a lower confinement layer) 12, a first waveguide layer (also referred to as a lower waveguide layer) 13, a quantum well active layer (also referred to as a light-emitting active region, light-emitting layer, etc.) 14, a second waveguide layer (also referred to as an upper waveguide layer) 15, a p-type transition compensation layer (TCL) 16, a p-type electron blocking layer (EBL) 17, a p-type confinement layer (also referred to as an upper confinement layer) 18, and a p-type ohmic contact layer 19. The acceptor impurity concentration in the p-type transition compensation layer 16 is higher than that in the p-type electron blocking layer 17, and the barrier of the p-type transition compensation layer 16 is higher than the barrier of the second waveguide layer 15 but lower than the barrier of the p-type electron blocking layer 17.

[0034] Specifically, the n-type substrate 11 and the n-type confinement layer 12 can be regarded as the n-type region of the laser epitaxial structure, and the p-type electron blocking layer 17, the p-type confinement layer 18 and the p-type ohmic contact layer 19 can be regarded as the p-type region of the laser epitaxial structure. The specified direction can be the longitudinal direction of the laser epitaxial structure, and the direction of the overall movement of electrons and holes can be parallel to the pointing direction.

[0035] Specifically, the acceptor impurity concentration in the p-type transition compensation layer 16 is 5-10 times that in the p-type electron blocking layer 17. Specifically, the acceptor impurity in both the p-type transition compensation layer 16 and the p-type electron blocking layer 17 is Mg, and the Mg doping concentration in the p-type transition compensation layer 16 is 1E20-5E20 cm⁻¹. -3 The Mg doping concentration in the p-type electron blocking layer 17 is 1E19-5E19 cm⁻¹ -3 .

[0036] Specifically, the quantum well active layer 14, the second waveguide layer 15, and the p-type transition compensation layer 16 are all formed of group III nitrides containing In, and the In content in the quantum well active layer 14 is greater than the In content in the second waveguide layer 15, which is greater than the In content in the p-type transition compensation layer 16. Alternatively, the quantum well active layer 14 and the second waveguide layer 15 are both formed of group III nitrides containing In, the p-type transition compensation layer 16 does not contain In, and the In content in the quantum well active layer 14 is greater than the In content in the second waveguide layer.

[0037] Specifically, the In content in the quantum well active layer 14 is 15-25 at.%, the In content in the second waveguide layer 15 is 3-6 at.%, and the In content in the p-type transition compensation layer 16 is 1.5-3 at.%.

[0038] Specifically, the p-type transition compensation layer 16 includes a Mg-doped p-type InGaN / GaN superlattice structure layer, a p-type InGaN layer, or a p-type GaN layer. The growth conditions for the p-type InGaN / GaN superlattice, p-type InGaN monolayer, or p-type GaN monolayer include a lower growth temperature range of 700-800℃; a higher growth pressure of 250-500 torr; and a higher ratio of ammonia and MO source, with a V / III ratio of 1000-10000. Under these growth conditions, the p-type transition compensation layer obtained has better crystal quality, fewer vacancies and defects, and the medium-low temperature growth ensures a higher In incorporation rate. The higher growth pressure improves crystal quality, and the high V / III ratio compensates for the insufficient N source at low temperatures.

[0039] Specifically, the thickness of the p-type transition compensation layer is 5-50 nm; in a specific embodiment, the p-type InGaN / GaN superlattice structure layer includes at least one period of InGaN / GaN superlattice, wherein the thickness of the InGaN layer in the InGaN / GaN superlattice is 1-5 nm and the thickness of the GaN layer is 1-5 nm.

[0040] Specifically, the n-type substrate 11 can be an n-GaN template of an n-GaN homo-substrate or a hetero-substrate.

[0041] Specifically, the n-type confinement layer 12 can be a Si-doped n-AlGaN layer, and the first waveguide layer 13 and the second waveguide layer 15 can both be undoped InGaN layers. It should be noted that when the laser wavelength is short, the first waveguide layer 13 and the second waveguide layer 15 can also be GaN layers.

[0042] Specifically, the active quantum well layer 14 can be an InGaN / GaN quantum well active layer. When an undoped InGaN layer is used as the first waveguide layer and the second waveguide layer, the In content in the first waveguide layer and the second waveguide layer is lower than the In content in the active quantum well layer. The In content in the first waveguide layer, the second waveguide layer and the light-emitting layer is determined by the laser wavelength.

[0043] Specifically, the p-type electron blocking layer 17 and the p-type confinement layer 18 can both be Mg-doped p-AlGaN layers, and the p-type ohmic contact layer can be a Mg-doped p-GaN layer.

[0044] For details, please refer to Figure 4 The present invention provides a laser epitaxial structure that addresses the problems of strong N-type region and weak P-type region in existing lasers, as well as the large lattice mismatch between the second waveguide layer and the p-type electron blocking layer. A p-type transition compensation layer is set between the second waveguide layer and the p-type electron blocking layer. Here, the In content in the p-type transition compensation layer is lower than that in the second waveguide layer. In the p-type transition compensation layer, p-InGaN and GaN are paired together. Before growing the p-type electron blocking layer with high Al content, lattice transition growth and preset compressive stress are performed to alleviate the problems of lattice mismatch between the second waveguide layer and the p-type electron blocking layer and the generation of tensile stress cracks in traditional laser epitaxial structures.

[0045] Meanwhile, in traditional lasers, Mg is passivated by H in GaN-based materials, and the energy to activate Mg-H bonds increases rapidly with the increase of Al content. Therefore, the Mg-doped p-type AlGaN electron blocking layer affects the overall Mg doping in the p-type region, resulting in increased resistance and affecting the laser's efficiency and lifetime. In this invention, by adding a transition compensation layer of Mg-doped p-type InGaN or Mg-doped p-type InGaN / GaN superlattice, In has a lower Mg-H bond energy for Mg doping in GaN materials and has an activation effect before growing AlGaN with low Mg doping efficiency. This improves the problem of low Mg concentration and slow hole concentration increase in p-type doping when only a p-type electron blocking layer is used. This greatly enhances the probability of electron and hole recombination in the quantum well active layer, improves radiative recombination, improves crystal quality, and thus increases the laser's lifetime. Furthermore, since the p-type transition compensation layer increases optical confinement, the laser's optical power output efficiency is also higher. The following will provide a further explanation of the technical solution, its implementation process, and its principles, in conjunction with the accompanying drawings and specific implementation examples.

[0046] Example 1

[0047] Please see Figure 3 An epitaxial structure A for a GaN-based laser includes an n-GaN substrate, a Si-doped n-AlGaN confinement layer, an undoped first InGaN waveguide layer, an InGaN / GaN quantum well active layer, an undoped second InGaN waveguide layer, a Mg-doped p-type InGaN / GaN superlattice transition compensation layer, a Mg-doped p-AlGaN electron blocking layer, a Mg-doped p-AlGaN confinement layer, and a Mg-doped p-GaN ohmic contact layer, stacked sequentially along a specified direction.

[0048] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an In GaN well layer thickness of 3 nm and an In content of 15 at.%; the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-type InGaN / GaN superlattice transition compensation layer comprises five periods of InGaN / GaN superlattices, each InGaN / GaN superlattice having an In GaN layer thickness of 3 nm and an In content of 1.5 at.%; the GaN layer has a thickness of 2 nm; and the Mg doping concentration in the p-type InGaN / GaN superlattice transition compensation layer is 1E20cm⁻¹.-3 The p-AlGaN electron blocking layer has a thickness of 20 nm, an Al content of 15 at.%, and a Mg doping concentration of 2E19 cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%. The p-GaN ohmic contact layer has a thickness of 10 nm.

[0049] Example 2

[0050] An epitaxial structure B for a GaN-based laser includes, sequentially stacked along a specified direction, an n-GaN substrate, a Si-doped n-AlGaN confinement layer, an undoped first InGaN waveguide layer, an InGaN / GaN quantum well active layer, an undoped second InGaN waveguide layer, a Mg-doped p-type InGaN transition compensation layer, a Mg-doped p-AlGaN electron blocking layer, a Mg-doped p-AlGaN confinement layer, and a Mg-highly doped p-GaN ohmic contact layer.

[0051] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an In GaN well layer thickness of 3 nm and an In content of 15 at.%; and the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-type InGaN transition compensation layer has a thickness of 25 nm and an In content of 1.5 at.%; and the Mg doping concentration in the p-type InGaN transition compensation layer is 1.6E20cm⁻¹. -3 The p-AlGaN electron blocking layer has a thickness of 20 nm, an Al content of 15 at.%, and a Mg doping concentration of 2E19 cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%. The p-GaN ohmic contact layer has a thickness of 10 nm.

[0052] Example 3

[0053] An epitaxial structure C for a GaN-based laser includes, sequentially stacked along a specified direction, an n-GaN substrate, a Si-doped n-AlGaN confinement layer, an undoped first InGaN waveguide layer, an InGaN / GaN quantum well active layer, an undoped second InGaN waveguide layer, a Mg-doped p-type GaN transition compensation layer, a Mg-doped p-AlGaN electron blocking layer, a Mg-doped p-AlGaN confinement layer, and a Mg-highly doped p-GaN ohmic contact layer.

[0054] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an In GaN well layer thickness of 3 nm and an In content of 15 at.%; and the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-type GaN transition compensation layer has a thickness of 25 nm, and the Mg doping concentration in the p-type GaN transition compensation layer is 2E20cm⁻¹. -3 The p-AlGaN electron blocking layer has a thickness of 20 μm, an Al content of 15 at.%, and a Mg doping concentration of 2E19 cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%. The p-GaN ohmic contact layer has a thickness of 10 nm.

[0055] Comparative Example 1

[0056] Please see Figure 1 An epitaxial structure D for a GaN-based laser includes an n-GaN template 21 on an n-GaN homo- or hetero-substrate, an n-AlGaN confinement layer 22, an undoped first InGaN or GaN waveguide layer 23, an InGaN / GaN quantum well light-emitting layer (or active region) 24, an undoped second InGaN or GaN waveguide layer 25, a Mg-doped p-AlGaN electron blocking layer 26, a Mg-doped p-AlGaN confinement layer 27, and a Mg-highly doped p-GaN ohmic contact layer 28, which are stacked sequentially along a specified direction.

[0057] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an In GaN well layer thickness of 3 nm and an In content of 15 at.%; and the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-AlGaN electron blocking layer has a thickness of 20 nm and an Al content of 15 at.%; and the Mg doping concentration is 2E19cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%. The p-GaN ohmic contact layer has a thickness of 10 nm.

[0058] The principle of this GaN-based laser is as follows: Figure 2 As shown, the majority carriers (electrons) are generated by the n-type GaN template on the n-type GaN homo-substrate or hetero-substrate and the Si-doped n-type AlGaN confinement layer, while the minority carriers (holes) are mainly generated by the p-type AlGaN electron blocking layer, the p-type AlGaN confinement layer, and the p-type GaN layer. Among them, the p-type AlGaN electron blocking layer is thinner and has a higher Al content, which can be used to block the electrons overflowing from the self-emitting layer. Under the driving action of high current density, a large number of electrons with small effective mass and fast mobility rush from the bottom of the conduction band to the emitting layer, while holes with large effective mass and slow mobility flow from the top of the valence band to the emitting layer. Due to the mismatch between the behavior of electrons and holes, a "strong N, weak P" pattern is formed. From the undoped second InGaN waveguide layer to the p-AlGaN electron blocking layer, the Mg doping (hole concentration) will slowly increase because the electron blocking layer requires a high Al content, resulting in a higher resistance value and a lower injection efficiency.

[0059] Comparative Example 2

[0060] An epitaxial structure E for a GaN-based laser includes, sequentially stacked along a specified direction, an n-GaN substrate, a Si-doped n-AlGaN confinement layer, an undoped first InGaN waveguide layer, an InGaN / GaN quantum well active layer, an undoped second InGaN waveguide layer, a Mg-doped p-type InGaN / GaN superlattice transition compensation layer, a Mg-doped p-AlGaN electron blocking layer, a Mg-doped p-AlGaN confinement layer, and a Mg-highly doped p-GaN ohmic contact layer.

[0061] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an InGaN well layer thickness of 3 nm and an In content of 15 at.%; the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-type InGaN / GaN superlattice transition compensation layer comprises five periods of InGaN / GaN superlattices, each InGaN / GaN superlattice having an InGaN layer thickness of 3 nm and an In content of 1.5 at.%; the GaN layer has a thickness of 2 nm; and the Mg doping concentration in the p-type InGaN / GaN superlattice transition compensation layer is 2E20cm⁻¹. -3 The p-AlGaN electron blocking layer has a thickness of 20 nm, an Al content of 15 at.%, and a Mg doping concentration of 1E20cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%. The p-GaN ohmic contact layer has a thickness of 10 nm.

[0062] Comparative Example 3

[0063] An epitaxial structure F for a GaN-based laser includes, sequentially stacked along a specified direction, an n-GaN substrate, a Si-doped n-AlGaN confinement layer, an undoped first InGaN waveguide layer, an InGaN / GaN quantum well active layer, an undoped second InGaN waveguide layer, a Mg-doped p-type InGaN transition compensation layer, a Mg-doped p-AlGaN electron blocking layer, a Mg-doped p-AlGaN confinement layer, and a Mg-highly doped p-GaN ohmic contact layer.

[0064] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an In GaN well layer thickness of 3 nm and an In content of 15 at.%; and the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-type InGaN transition compensation layer has a thickness of 25 nm and an In content of 1.5 at.%; and the Mg doping concentration in the p-type InGaN transition compensation layer is 5E20cm⁻¹. -3The p-AlGaN electron blocking layer has a thickness of 20 nm, an Al content of 15 at.%, and a Mg doping concentration of 1E19 cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%; the p-GaN ohmic contact layer has a thickness of 10 nm.

[0065] Comparative Example 4

[0066] An epitaxial structure G for a GaN-based laser includes, sequentially stacked along a specified direction, an n-GaN substrate, a Si-doped n-AlGaN confinement layer, an undoped first InGaN waveguide layer, an InGaN / GaN quantum well active layer, an undoped second InGaN waveguide layer, a Mg-doped p-type InGaN / GaN superlattice transition compensation layer, a Mg-doped p-AlGaN electron blocking layer, a Mg-doped p-AlGaN confinement layer, and a Mg-highly doped p-GaN ohmic contact layer.

[0067] In this embodiment, the n-AlGaN confinement layer has a thickness of 850 nm and an Al content of 8 at.%; the first InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the InGaN / GaN quantum well active layer comprises two periods of InGaN / GaN quantum wells, each InGaN / GaN quantum well having an InGaN well layer thickness of 3 nm and an In content of 15 at.%; the GaN barrier layer has a thickness of 7 nm; the second InGaN waveguide layer has a thickness of 60 nm and an In content of 3 at.%; the p-type InGaN / GaN superlattice transition compensation layer comprises five periods of InGaN / GaN superlattices, each InGaN / GaN superlattice having an InGaN layer thickness of 3 nm and an In content of 20 at.%; the GaN layer has a thickness of 2 nm; and the Mg doping concentration in the p-type InGaN / GaN superlattice transition compensation layer is 2E20cm⁻¹. -3 The p-AlGaN electron blocking layer has a thickness of 20 nm, an Al content of 15 at.%, and a Mg doping concentration of 2E19 cm⁻¹. -3 The p-AlGaN confinement layer has a thickness of 850 nm and an Al content of 5 at.%. The p-GaN ohmic contact layer has a thickness of 10 nm.

[0068] Using the same chip fabrication process, the epitaxial structures of the GaN-based lasers in Examples 1-3 and Comparative Examples 1-4 were fabricated to form GaN-based lasers. The obtained GaN-based lasers were then tested, and the test results are shown in Table 1.

[0069] Table 1 shows the performance characterization results of the GaN-based lasers formed from the epitaxial structures in Examples 1-3 and Comparative Examples 1-4.

[0070]

[0071] As can be seen from Table 1, the threshold voltage of the GaN-based laser provided by this invention is reduced, mainly due to the compensation effect of Mg doping in the P-type region; the lifetime of the GaN-based laser is extended, mainly due to the improvement of crystal quality after the lattice transition; and finally, the radiative recombination efficiency of the GaN-based laser is increased to a certain extent, mainly reflected in the increase of lasing power.

[0072] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A laser epitaxial structure with a transition compensation structure, comprising an n-type confinement layer, a first waveguide layer, a quantum well active layer, a second waveguide layer, a p-type electron blocking layer, a p-type confinement layer, and a p-type ohmic contact layer sequentially arranged along a specified direction, characterized in that: The epitaxial structure further includes a p-type transition compensation layer disposed between the second waveguide layer and the p-type electron blocking layer. The barrier of the p-type transition compensation layer is higher than the barrier of the second waveguide layer but lower than the barrier of the p-type electron blocking layer. The acceptor impurity concentration in the p-type transition compensation layer is higher than the acceptor impurity concentration in the p-type electron blocking layer. The p-type transition compensation layer is formed of a group III nitride containing In.

2. The laser epitaxial structure with transition compensation according to claim 1, characterized in that: The acceptor impurity concentration in the p-type transition compensation layer is 5-10 times that in the p-type electron blocking layer.

3. The laser epitaxial structure with transition compensation structure according to claim 2, characterized in that: The acceptor impurity in the p-type transition compensation layer and the p-type electron blocking layer is Mg, and the Mg doping concentration in the p-type transition compensation layer is 1E20-5E20cm⁻¹. -3 The Mg doping concentration in the p-type electron blocking layer is 1E19-5E19 cm⁻¹ -3 .

4. The laser epitaxial structure with transition compensation structure according to claim 1 or 2, characterized in that: The quantum well active layer, the second waveguide layer, and the p-type transition compensation layer are all formed of group III nitrides containing In, and the In content in the quantum well active layer is greater than the In content in the second waveguide layer, which in turn is greater than the In content in the p-type transition compensation layer.

5. The laser epitaxial structure with transition compensation structure according to claim 4, characterized in that: The In content in the p-type transition compensation layer is 1.5 at.% to 3 at.%, the In content in the quantum well active layer is 15 at.% to 25 at.%, and the In content in the second waveguide layer is 3 at.% to 6 at.%.

6. The laser epitaxial structure with transition compensation according to claim 4, characterized in that: The p-type transition compensation layer includes a p-type InGaN / GaN superlattice structure layer or a p-type InGaN layer.

7. The laser epitaxial structure with transition compensation according to claim 6, characterized in that: The thickness of the p-type transition compensation layer is 5nm-50nm.

8. The laser epitaxial structure with transition compensation according to claim 6, characterized in that: The p-type InGaN / GaN superlattice structure layer comprises at least one periodic InGaN / GaN superlattice, wherein the thickness of the InGaN layer in the InGaN / GaN superlattice is 1nm-5nm and the thickness of the GaN layer is 1nm-5nm.

9. The laser epitaxial structure with transition compensation structure according to claim 4, characterized in that: The active layer of the quantum well includes an InGaN / GaN quantum well, and the first waveguide layer and the second waveguide layer are both made of InGaN.

10. The laser epitaxial structure with transition compensation according to claim 1, characterized in that: Both the p-type electron blocking layer and the p-type confinement layer are made of AlGaN.

11. The laser epitaxial structure with transition compensation according to claim 1, characterized in that, include: The n-AlGaN confinement layer, the first InGaN waveguide layer, the InGaN / GaN quantum well active layer, the second InGaN waveguide layer, the p-type transition compensation layer, the p-AlGaN electron blocking layer, the p-AlGaN confinement layer and the p-GaN ohmic contact layer are arranged sequentially along a specified direction. The p-type transition compensation layer includes a p-type InGaN / GaN superlattice structure layer or a p-type InGaN layer.

12. A laser, characterized in that... The laser epitaxial structure having a transition compensation structure as described in any one of claims 1-11.

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