Epitaxial structure of semiconductor laser and preparation method thereof

Abstract

The invention provides an epitaxial structure of a semiconductor laser and a preparation method thereof. The epitaxial structure comprises a first waveguide layer, a first barrier layer, a first barrier layer, a quantum well layer, a second barrier layer, a second barrier layer and a second waveguide layer which are stacked from bottom to top. By adjusting different contents of an aluminum element and a gallium element in the first waveguide layer, the first barrier layer, the second barrier layer and the second waveguide layer, adjusting different contents of a gallium element and an indium element in the first barrier layer, and adjusting different contents of an aluminum element, a gallium element and an indium element in the second barrier layer, a first conduction band difference delta Ec11 is greater than 70meV, a second valence band difference delta Ev21 is greater than 240meV, and a second valence band difference delta Ev21 is greater than 240meV. The first valence band difference delta Ev11 and the second conduction band difference delta Ec21 are both smaller than or equal to 0 meV. The epitaxial structure can well balance the limiting effect on electrons and holes, so that the limiting capability of the epitaxial structure on current carriers is optimal, and the output efficiency of the device is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to an epitaxial structure of a semiconductor laser and a preparation method thereof. Background Art

[0002] In the epitaxial structure design of semiconductor laser chips, a design method of inserting a thin high-bandgap carrier blocking layer between low-bandgap waveguide layers is adopted to achieve the purpose of confining carriers (especially electrons) as much as possible in the quantum well. However, in the current design process of adjusting the epitaxial structure, the degree of carrier confinement is often not high, and the output efficiency of semiconductor lasers cannot be greatly improved. Summary of the invention

[0003] In view of this, the present application provides an epitaxial structure of a semiconductor laser and a preparation method thereof. The epitaxial structure design of the semiconductor laser of the present application can balance the restriction effects on electrons and holes, so that the epitaxial structure's restriction ability for carriers reaches an optimal state, and the output efficiency of the semiconductor laser is greatly improved; at the same time, the lattice matching state between the layers of the epitaxial structure is good, which is suitable for large-scale and batch production.

[0004] The technical solutions provided by this application are as follows: An epitaxial structure of a semiconductor laser comprises: a first waveguide layer, a first blocking layer, a first barrier layer, a quantum well layer, a second barrier layer, a second blocking layer, a second waveguide layer, A first conduction band difference ΔEc11 between the second blocking layer and the second barrier layer is greater than 70 meV, a second valence band difference ΔEv21 between the first blocking layer and the first barrier layer is greater than 240 meV, a first valence band difference ΔEv11 between the second blocking layer and the second waveguide layer is equal to a meV, and a second conduction band difference ΔEc21 between the first blocking layer and the first waveguide layer is equal to b meV, wherein a≤0, b≤0.

[0005] In one embodiment, the content of aluminum in the first waveguide layer is greater than that in the first barrier layer; and the content of aluminum in the second waveguide layer is greater than that in the second barrier layer.

[0006] In one embodiment, the first waveguide layer is Al x2 Ga 1-x2 As, 0.2≤x2≤0.4; The first barrier layer is Ga x3 In 1-x3 P, x3 ≥ 0.55; The first barrier layer is Al x4 Ga1-x4 As, 0.05≤x4≤0.20; The second barrier layer is Al x6 Ga 1-x6 As, 0.05≤x6≤0.20; The second barrier layer is Al x7 Ga y7 In 1-x7-y7 As, 1-x7-y7<0.2, 0.25≤x7≤0.45; The second waveguide layer is Al x8 Ga 1-x8 As, 0.20≤x8≤0.30.

[0007] In one embodiment, the first confinement layer is Al x1 Ga 1-x1 As, 0.25≤x1≤0.80; The quantum well layer is In x5 Ga 1-x5 As, 0≤x5≤0.25; The second confinement layer is Al x9 Ga 1-x9 As, 0.35≤x9≤0.90.

[0008] In one embodiment, the thickness of the first confinement layer is 1.5-3 microns, the thickness of the first waveguide layer is 0.3-1.5 microns, the thickness of the first barrier layer is 0.004-0.030 microns, the thickness of the first barrier layer is 0.003-0.060 microns, the thickness of the quantum well layer is 0.006-0.010 microns, the thickness of the second barrier layer is 0.003-0.060 microns, the thickness of the second barrier layer is 0.004-0.030 microns, the thickness of the second waveguide layer is 0.3-1.0 microns, and the thickness of the second confinement layer is 0.5-2 microns.

[0009] In one embodiment, the first waveguide layer is Al m1 Ga n1 In 1-m1-n1 As, 0.25≤m1≤0.45, 0.05≤n1≤0.20; The first barrier layer is Ga m2 In 1-m2 P, 0.60≤m2≤0.85; The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25; The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25; The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60; The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20.

[0010] In one embodiment, the quantum well layer is Al m4 Ga n4 In 1-m4-n4 As, 0.02≤m4≤0.10, 0.30≤n4≤0.50; The first confinement layer and the second confinement layer are both InP.

[0011] In one embodiment, the thickness of the first confinement layer is 1.5-3 microns, the thickness of the first waveguide layer is 0.3-1.5 microns, the thickness of the first barrier layer is 0.004-0.030 microns, the thickness of the first barrier layer is 0.003-0.060 microns, the thickness of the quantum well layer is 0.006-0.012 microns, the thickness of the second barrier layer is 0.003-0.060 microns, the thickness of the second barrier layer is 0.004-0.030 microns, the thickness of the second waveguide layer is 0.1-1.0 microns, and the thickness of the second confinement layer is 0.5-2.5 microns.

[0012] The present application provides a method for preparing an epitaxial structure of a semiconductor laser, comprising: Growing a first waveguide layer, a first blocking layer, a first potential barrier layer, a quantum well layer, a second potential barrier layer, a second blocking layer, and a second waveguide layer in a stacked manner on a substrate; During the growth of the first waveguide layer, the first barrier layer, the first barrier layer, the second barrier layer, the second barrier layer and the second waveguide layer: the contents of aluminum and gallium in the first waveguide layer, the first barrier layer, the second barrier layer and the second waveguide layer are adjusted, the contents of gallium and indium in the first barrier layer are adjusted, and the contents of aluminum and indium in the second barrier layer are adjusted, so that a first conduction band difference ΔEc11 between the second barrier layer and the second barrier layer is greater than 70 meV, a second valence band difference ΔEv21 between the first barrier layer and the first barrier layer is greater than 240 meV, a first valence band difference ΔEv11 between the second barrier layer and the second waveguide layer is equal to a meV, and a second conduction band difference ΔEc21 between the first barrier layer and the first waveguide layer is equal to b meV, where a≤0 and b≤0.

[0013] In one embodiment, the first confinement layer is AlGaAs material; The first waveguide layer is made of AlGaAs material; The first barrier layer is made of GaInP material; The first barrier layer is made of AlGaAs material; The quantum well layer is made of InGaAs material; The second barrier layer is made of AlGaAs material; The second barrier layer is made of AlGaInAs material; The second waveguide layer is made of AlGaAs material; The second confinement layer is made of AlGaAs material.

[0014] In one embodiment, when growing the first waveguide layer Al x2 Ga 1-x2 When As, the growth thickness is controlled at 0.5~1.5μm, the growth rate is 0.1~0.7nm / s, and the Al content range satisfies: 0.2≤x2≤0.4; When growing the first barrier layer Al x4 Ga 1-x4 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.1nm / s, and the Al content range satisfies: 0.05≤x4≤0.20; When growing the second barrier layer Al x6 Ga 1-x6 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.1nm / s, and the Al content range satisfies: 0.05≤x6≤0.20; In growing the second waveguide layer Al x8Ga 1-x8 When As is added, the growth thickness is controlled at 0.3~1.0μm, the growth rate is 0.1~0.7nm / s, and the Al content range satisfies: 0.20≤x8≤0.30.

[0015] In one embodiment, it includes: In growing the first barrier layer Ga x3 In 1-x3 When P, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.1 nm / s, and the In content range satisfies: x3≥0.55; after the first barrier layer is grown, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged; as well as, In growing the second barrier layer Al x7 Ga y7 In 1-x7-y7 As, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.1 nm / s, and the In content range satisfies: 1-x7-y7<0.2; the second barrier layer Al x7 Ga y7 In 1-x7-y7 After the As growth is completed, stop injecting the reaction source for 15-20 seconds to keep the temperature in the chamber constant.

[0016] In one embodiment, it includes: When forming the first barrier layer, the growth temperature is selected to be 680° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.1 nm / s; When forming the second barrier layer, the growth temperature is selected to be 680° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.1 nm / s.

[0017] In one embodiment, the quantum well layer In x5 Ga 1-x5 During As deposition, the deposition temperature in the chamber is controlled to be lowered to 580-640°C, the growth thickness is controlled to be 0.006-0.01 μm, the growth rate is 0.02-0.1 nm / s, and the In content satisfies: 0≤x5≤0.25; After the quantum well layer is formed, the reaction source is stopped for 15-20 seconds to keep the temperature constant.

[0018] In one embodiment, the first waveguide layer is Al m1 Ga n1 In 1-m1-n1As, 0.25≤m1≤0.45, 0.05≤n1≤0.20; The first barrier layer is Ga m2 In 1-m2 P, 0.60≤m2≤0.85; The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25; The quantum well layer is Al m4 Ga n4 In 1-m4-n4 As, 0.02≤m4≤0.10, 0.30≤n4≤0.50; The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25; The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60; The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20; The first confinement layer and the second confinement layer are both InP.

[0019] In one embodiment, when growing the first waveguide layer Al m1 Ga n1 In 1-m1-n1 When As, the growth thickness is controlled at 0.3~1.5μm, the growth rate is 0.05~0.8nm / s, and the content range of Al and Ga satisfies: 0.25≤m1≤0.45, 0.05≤n1≤0.20; In growing the first barrier layer Ga m2 In 1-m2 When P, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.8 nm / s, and the In content range satisfies: 0.60≤m2≤0.85; After the growth of the first barrier layer is completed, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged; When growing the first barrier layer Al m3 Ga n3 In 1-m3-n3When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.8nm / s, and the content range of Al and Ga satisfies: 0.20≤m3≤0.40, 0.10≤n3≤0.25; In the quantum well layer Al m4 Ga n4 In 1-m4-n4 During As deposition, the deposition temperature in the chamber is controlled to be lowered to 580-700°C, the growth thickness is controlled to be 0.006-0.012 μm, the growth rate is 0.02-0.1 nm / s, and the contents of Al and Ga satisfy the following conditions: 0.02≤m4≤0.10, 0.30≤n4≤0.50; after the quantum well layer is formed, the reaction source is stopped for 15-20 seconds to keep the temperature constant; When growing the second barrier layer Al m5 Ga n5 In 1-m5-n5 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.8nm / s, and the content range of Al and Ga satisfies: 0.20≤m5≤0.40, 0.10≤n5≤0.25; In growing the second barrier layer Al m6 In 1-m6 When As, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.8 nm / s, and the Al content range satisfies: 0.45≤m6≤0.60; after the second barrier layer is grown, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged; In growing the second waveguide layer Al m7 Ga n7 In 1-m7-n7 When As is added, the growth thickness is controlled at 0.1~1.0μm, the growth rate is 0.05~0.8nm / s, and the content ranges of Al and Ga satisfy: 0.35≤m7≤0.50, 0.10≤n7≤0.20.

[0020] In one embodiment, it includes: When forming the first barrier layer, the growth temperature is selected to be 630° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s; When forming the second barrier layer, the growth temperature is selected to be 630° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s.

[0021] The epitaxial structure design of the semiconductor laser provided in the present application can well balance the restriction effect on electrons and holes, so that the epitaxial structure can achieve the best restriction ability for carriers, and the output efficiency of the semiconductor laser is greatly improved; at the same time, the adaptive adjustment of the indium content in the first blocking layer (hole blocking layer) and the second blocking layer (electron blocking layer) is based on the adjustment of the content of aluminum and gallium in the first waveguide layer, the first barrier layer, the second barrier layer and the second waveguide layer, so that the indium element can be kept in a suitable range, so that the lattice matching state between the layers in the epitaxial structure is good, which is suitable for large-scale and batch production. In addition, the epitaxial structure design of the semiconductor laser in the embodiment of the present application has higher temperature characteristics and higher internal quantum efficiency, which helps to achieve higher output power, especially the output power and electro-optical conversion efficiency under high temperature power conditions will be greatly improved, which greatly expands the application direction of semiconductor lasers.

[0022] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 The energy band diagram of a typical epitaxial structure with a carrier blocking layer; Figure 2 A schematic diagram of an energy band of an epitaxial structure provided in one embodiment of the present application; Figure 3 A schematic diagram of an energy band of an epitaxial structure provided in another embodiment of the present application; Figure 4 An embodiment of the present application provides a substrate and a buffer layer, and an epitaxial structure of a semiconductor laser grown thereon.

[0025] Reference numerals: N-type confinement layer 01, N-type waveguide layer 02, N-type hole blocking layer 03, N-type barrier layer 04, quantum well 05, P-type barrier layer 06, P-type electron blocking layer 07, P-type waveguide layer 08, P-type confinement layer 09, Substrate 1, buffer layer 10, Epitaxial structure 100 includes a first confinement layer 11 , a first waveguide layer 12 , a first barrier layer 13 , a first barrier layer 14 , a quantum well layer 15 , a second barrier layer 16 , a second barrier layer 17 , a second waveguide layer 18 , a second confinement layer 19 , and a cap layer 20 . DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0027] The applicant has found through a series of studies that in the epitaxial structure design of semiconductor lasers, the typical bandgap design of GaAs / AlGaAs-based epitaxial structure with carrier blocking layer is as follows: Figure 1 As shown, from left to right are the N region formed by N-type doping, the quantum well 05 (QW) and the P region formed by P-type doping, wherein the N region includes the N-type confinement layer 01, the N-type waveguide layer 02, and the N-type hole blocking layer 03; the N-type barrier layer 04 (also called the waveguide layer), which generally has the same composition as the N-type waveguide layer 02; the quantum well 05 (QW) can be made of GaAs material, InGaAs material or InAlGaAs material, and the required energy band needs to be designed according to different wavelength requirements, while considering the effect of quantum well strain on gain and growth quality, and selecting a suitable quantum well material; the P region includes the P-type barrier layer 06 (also called the waveguide layer), the P-type electron blocking layer 07, the P-type waveguide layer 08, which generally has the same composition as the P-type barrier layer 06, and the P-type confinement layer 09.

[0028] like Figure 1As shown, the typical epitaxial structure bandgap design with carrier blocking layer has two characteristics: the P-type electron blocking layer 07 restricts the movement of electrons in the N region to the P region, and also restricts the movement of holes in the P region to the quantum well 05 to a certain extent; the N-type hole blocking layer 03 restricts the movement of holes in the P region to the N region, and also restricts the movement of electrons in the N region to the quantum well 05 to a certain extent. Therefore, it is necessary to balance the first conduction band difference ΔE between the P-type electron blocking layer 07 and the P-type barrier layer 06 c1 The first valence band difference ΔE between the P-type electron blocking layer 07 and the P-type waveguide layer 08 v1 , so as to increase the first conduction band difference ΔE c1 Without causing too high a first valence band difference ΔE v1 At the same time, it is necessary to balance the second conduction band difference ΔE between the N-type hole blocking layer 03 and the N-type waveguide layer 02 c2 The second valence band difference ΔE between the N-type hole blocking layer 03 and the N-type barrier layer 04 v2 , so as to increase the second valence band difference ΔE v2 Without causing too high a second conduction band difference ΔE c2 purpose.

[0029] In addition, the applicant of the present application has found that in the process of adjusting the proportions of various elements in the epitaxial structure, one cannot simply pursue the energy band difference, but also needs to match the In content in the P-type electron blocking layer 07 and the N-type hole blocking layer 03 to avoid a relatively high In content that cannot achieve a good matching state with the AlGaAs material, resulting in greater difficulty in growing epitaxial materials and being unfavorable for large-scale, batch production.

[0030] Based on the above research conclusions, the applicant provides a Figure 2 , Figure 3 and Figure 4 The epitaxial structure design shown includes: a first confinement layer 11, a first waveguide layer 12, a first blocking layer (hole blocking layer) 13, a first barrier layer 14, a quantum well layer 15, a second barrier layer 16, a second blocking layer (electron blocking layer) 17, a second waveguide layer 18, and a second confinement layer 19, which are stacked in sequence from bottom to top. Figure 2 In the embodiment, the first confinement layer 11 is made of AlGaAs material, the first waveguide layer 12 is made of AlGaAs material, the first blocking layer 13 (hole blocking layer) is made of GaInP material, the first barrier layer 14 is made of AlGaAs material, the quantum well layer 15 is made of InGaAs material, the second barrier layer 16 is made of AlGaAs material, the second blocking layer 17 (electron blocking layer) is made of AlGaInAs material, the second waveguide layer 18 is made of AlGaAs material, and the second confinement layer 19 is made of AlGaAs material.

[0031] See also Figure 4 The epitaxial structure 100 can be formed on an N-type GaAs substrate or an InP substrate, and a buffer layer 10 can be formed before forming the epitaxial structure 100 on the substrate 1. When the epitaxial structure 100 is formed on the N-type substrate 1, the first confinement layer 11 is an N-type confinement layer, the first waveguide layer 12 is an N-type waveguide layer, the first blocking layer 13 is a hole blocking layer, the first barrier layer 14 is an N-type barrier layer, the quantum well layer 15, the second barrier layer 16 are P-type barrier layers, the second blocking layer 17 is an electron blocking layer, the second waveguide layer 18 is a P-type waveguide layer, and the second confinement layer 19 is a P-type confinement layer.

[0032] In one embodiment, Figure 2 As shown, an N-type epitaxial structure 100 is formed on a GaAs substrate, and further includes a first confinement layer below the first waveguide layer, and further includes a second confinement layer above the second waveguide layer. The first confinement layer is AlGaAs material, the first waveguide layer is AlGaAs material, the first barrier layer is GaInP material, the first barrier layer is AlGaAs material, the quantum well layer is InGaAs material, the second barrier layer is AlGaAs material, the second barrier layer is AlGaInAs material, the second waveguide layer is AlGaAs material, and the second confinement layer is AlGaAs material. The material combination in the above embodiment is only a typical and practically executable preferred combination. In other embodiments, the material combination may be variable, for example, the quantum well structure may also be an InAlGaAs structure.

[0033] By adjusting the contents of aluminum and gallium in the first waveguide layer 12, the first barrier layer 14, the second barrier layer 16 and the second waveguide layer 18, adjusting the contents of gallium and indium in the first blocking layer (hole blocking layer) 13, and adjusting the contents of aluminum, gallium and indium in the second blocking layer 17 (electron blocking layer), the first conduction band difference ΔEc11 between the second blocking layer 17 (electron blocking layer) and the second barrier layer 16 is greater than 70 meV, the second valence band difference ΔEv21 between the first blocking layer 13 (hole blocking layer) and the first barrier layer 14 is greater than 240 meV, the first valence band difference ΔEv11 between the second blocking layer 17 (electron blocking layer) and the second waveguide layer 18 is equal to a meV, and the second conduction band difference ΔEc21 between the first blocking layer 13 (hole blocking layer) and the first waveguide layer 12 is equal to b meV, wherein a≤0 and b≤0.

[0034] In this embodiment, by first adjusting the content of aluminum and gallium in the second barrier layer 16 and the second waveguide layer 18, and then adjusting the content of aluminum, gallium and indium in the second blocking layer (electron blocking layer) 17, a second blocking layer 17 (electron blocking layer) with a stronger electron blocking effect can be obtained, and at the same time, it can ensure that the holes in the valence band pass smoothly through the second blocking layer 17 (electron blocking layer) into the quantum well layer 15 (the first valence band difference ΔEv11≈0). As shown in Table 1 below, the stronger electron blocking effect is reflected in: the first conduction band difference ΔEc11 between the second blocking layer 17 (electron blocking layer) and the second barrier layer 16>70meV, which is better than the first conduction band difference (ΔEc1≈60meV) in the prior art.

[0035] Table 1 is an example of the change of the element content and the band difference of the second barrier layer 16, the second blocking layer 17, and the second waveguide layer 18.

[0036] Similarly, by first adjusting the content of aluminum and gallium in the first waveguide layer 12 and the first barrier layer 14, and then adjusting the content of gallium and indium in the first barrier layer 13 (hole barrier layer), a first barrier layer 13 (hole barrier layer) with a stronger hole blocking effect can be obtained, and at the same time, it can be ensured that the electrons in the conduction band pass smoothly through the first barrier layer 13 (hole barrier layer) into the quantum well layer 15 (that is, the second conduction band difference ΔEc21≈0 is ensured). As shown in Table 2 below, the stronger hole blocking effect is reflected in: the second valence band difference ΔEv21 between the first barrier layer 13 (hole barrier layer) and the first barrier layer 14 is greater than 240meV, which is better than the second valence band difference (ΔEv2≈200meV) in the prior art.

[0037] Table 2 shows an example of the change of the element content and the energy band difference of the first waveguide layer 12, the first blocking layer 13, and the first barrier layer 14.

[0038] Therefore, the epitaxial structure design of the semiconductor laser in the present application can well balance the restriction effect on electrons and holes, so that the epitaxial structure can achieve the best restriction ability for carriers, and the output efficiency of the semiconductor laser is greatly improved; at the same time, the adjustment of the gallium and indium content in the first blocking layer 13 (hole blocking layer) and the second blocking layer 17 (electron blocking layer) can keep the gallium and indium elements in a suitable range by relying on the adjustment of the aluminum and gallium content in the first waveguide layer 12, the first barrier layer 14, the second barrier layer 16 and the second waveguide layer 18, so that the lattice matching state between the layers in the epitaxial structure is good, which is suitable for large-scale and batch production. In addition, the epitaxial structure design of the semiconductor laser in the embodiment of the present application has higher temperature characteristics and higher internal quantum efficiency, which helps to achieve higher output power, especially the output power and electro-optical conversion efficiency under high temperature power conditions will be greatly improved, which greatly expands the application direction of semiconductor lasers.

[0039] In a specific embodiment, the aluminum content in the first waveguide layer 12 may be greater than that in the first barrier layer 14 ; and the aluminum content in the second waveguide layer 18 may be greater than that in the second barrier layer 16 .

[0040] In this embodiment, the content of aluminum in the first waveguide layer 12 is greater than the content of aluminum in the first barrier layer 14, which can help to design a larger second valence band difference ΔEv21 between the first barrier layer 13 (hole blocking layer) and the first barrier layer 14 when adjusting the different contents of gallium and indium in the first barrier layer 13 (hole blocking layer), while ensuring that the second conduction band difference ΔEc21=b meV between the first barrier layer 13 (hole blocking layer) and the first waveguide layer 12, where b≤0.

[0041] Similarly, the content of aluminum in the second waveguide layer 18 is greater than the content of aluminum in the second barrier layer 16, which can help to design a larger first conduction band difference ΔEc11 between the second blocking layer 17 (electron blocking layer) and the second barrier layer 16 when adjusting the contents of aluminum, gallium and indium in the second blocking layer 17 (electron blocking layer), while ensuring that the first valence band difference ΔEv11=a meV between the second blocking layer 17 (electron blocking layer) and the second waveguide layer 18, where a≤0.

[0042] In one embodiment, more specifically, the first waveguide layer 12 may be Al 0.3 Ga 0.7 As, the first barrier layer 14 is Al 0.15 Ga 0.85 As, and the second waveguide layer 18 is Al 0.25 Ga0.75 As, the second barrier layer 16 is Al 0.1 Ga 0.9 As.

[0043] In one embodiment, the first waveguide layer 12 is Al x2 Ga 1-x2 As, 0.2≤x2≤0.4, for example, x2 can be set to 0.2, 0.26, 0.30, 0.35, 0.4 or other values.

[0044] The first blocking layer (hole blocking layer) 13 is Ga x3 In 1-x3 P, x3 ≥ 0.55, for example, x3 can be set to 0.57, 0.6, 0.75, 0.8, 0.9, 0.95 or other values.

[0045] The first barrier layer 14 is Al x4 Ga 1-x4 As, 0.05≤x4≤0.20, for example, x4 can be set to 0.06, 0.07, 0.10, 0.11, 0.13, 0.15, 0.17, 0.19 or other values.

[0046] The second barrier layer 16 is Al x6 Ga 1-x6 As, 0.05≤x6≤0.20, for example, x6 can be set to 0.07, 0.09, 0.10, 0.12, 0.14, 0.15, 0.18, 0.19 or other values.

[0047] The second blocking layer (electron blocking layer) 17 is Al x7 Ga y7 In 1-x7-y7 As, 1-x7-y7<0.2, 0.25≤x7≤0.45, for example, x7 can be set to 0.40, and y7 can be set to 0.45.

[0048] The second waveguide layer 18 is Al x8 Ga 1-x8 As, 0.20≤x8≤0.30, for example, x8 can be set to 0.2, 0.25, 0.28 or other values.

[0049] The reduction of Al content in the first barrier layer 14 and the second barrier layer 16 leads to a reduction of In content in the first barrier layer 13 (hole barrier layer) and the second barrier layer 17 (electron barrier layer). The reduction of In content is conducive to the growth of epitaxial materials, so the difficulty of epitaxial growth can be greatly reduced through the epitaxial structure design in the embodiment of the present application.

[0050] Due to the low Al content (Al content is between 0.05-0.15) in the first barrier layer 14 and the second barrier layer 16, the first barrier layer 13 (hole barrier layer) and the second barrier layer 17 (electron barrier layer) can achieve a higher band gap difference with a lower In content, thereby achieving better carrier confinement. Figure 2 The band gap difference between ΔEc11 and ΔEc21 can be easily achieved to be higher than the typical design (ΔEc11>70meV and ΔEc21>240meV). At the same time, the blocking effect of the second blocking layer 17 (electron blocking layer) on holes can be reduced to a very low level or even eliminated, and the blocking effect of the first blocking layer 13 (hole blocking layer) on electrons can be reduced to a very low level or even eliminated, which can effectively improve the carrier injection efficiency and the carrier confinement capability, and the growth tolerance is relatively large.

[0051] Furthermore, the lower Al content of the first barrier layer 14 and the second barrier layer 16 will reduce the series resistance of the overall design of the semiconductor laser, and can achieve a lower voltage and a higher electro-optical conversion efficiency. The above-mentioned epitaxial structure design of the present application fundamentally solves the problem of voltage increase and low efficiency caused by the use of high Al content materials in the first barrier layer 14 and the second barrier layer 16 in order to ensure lower carrier leakage in the original high-temperature structure design. This design can not only ensure the suppression of carrier leakage at high temperature and achieve high power output; it can also ensure a lower voltage and ultimately achieve high efficiency. Therefore, the design is very beneficial for both high temperature and normal temperature, and can form a laser that works stably and efficiently in a large temperature range, providing a huge tolerance for use in different application environments.

[0052] In this embodiment, the above-mentioned value ranges are all verified by the applicant through epitaxial growth design, and can balance the restriction effect on electrons and holes, so that the carrier restriction ability of the epitaxial structure reaches the optimal state, and the output efficiency of the semiconductor laser is greatly improved; at the same time, the gallium and indium contents in the first blocking layer 13 (hole blocking layer) and the second blocking layer 17 (electron blocking layer) are maintained in a suitable range, and the lattice matching state between the layers in the epitaxial structure is good, which is suitable for large-scale and batch production.

[0053] In one embodiment, the first confinement layer 11 is Al x1 Ga 1-x1 As, 0.25≤x1≤0.80, for example, x1 can be 0.27, 0.29, 0.32, 0.37, 0.39, 0.42, 0.47, 0.51, 0.58, 0.63, 0.69, 0.72, 0.76, 0.79, 0.80 or other values. The quantum well layer 15 is In x5 Ga 1-x5 As, 0≤x5≤0.25. The second limiting layer 19 is Al x9Ga 1- x9 As, 0.35≤x9≤0.90, for example, x9 can be 0.37, 0.39, 0.43, 0.57, 0.69, 0.73, 0.80, 0.84, 0.87, 0.89, 0.90 or other values.

[0054] In this embodiment, the contents of the first confinement layer 11 , the quantum well layer 15 and the second confinement layer 19 are further designed to form a complete epitaxial structure of a high-power semiconductor laser.

[0055] In one embodiment, the thickness of the first confinement layer 11 can be set to 1.5-3 microns, the thickness of the first waveguide layer 12 can be set to 0.3-1.5 microns, the thickness of the first blocking layer 13 (hole blocking layer) can be set to 0.004-0.030 microns, the thickness of the first barrier layer 14 can be set to 0.003-0.060 microns, the thickness of the quantum well layer 15 can be set to 0.006-0.010 microns, the thickness of the second barrier layer 16 can be set to 0.003-0.060 microns, the thickness of the second blocking layer 17 (electron blocking layer) can be set to 0.004-0.030 microns, the thickness of the second waveguide layer 18 can be set to 0.3-1.0 microns, and the thickness of the second confinement layer 19 can be set to 0.5-2 microns.

[0056] In the present application, the Al content (band gap) in the first confinement layer 11, the first waveguide layer 12, the second waveguide layer 18, and the second confinement layer 19 is synchronously correlated with the quantum well layer 15 (wavelength, quantum well band gap). Specifically, the quantum well band gap Eg is negatively correlated with the wavelength, so the longer the wavelength of the quantum well layer, the smaller the quantum well band gap Eg, and the corresponding band gap Eg of the waveguide layer and the barrier layer is also reduced, which can meet the effective band gap difference, achieve the purpose of reducing resistance, and achieve higher efficiency.

[0057] More specifically, the lasing wavelength of a semiconductor laser chip depends on the energy level difference between the bottom of the conduction band (the first sub-energy level of electrons) and the top of the valence band (the first sub-energy level of holes) of the quantum well in the epitaxial structure. Ideally, it satisfies:

[0058] in, is the lasing wavelength, is Planck's constant, is the speed of light, is the effective band gap from the bottom of the conduction band to the top of the valence band, is the first sub-level of the bottom electron of the conduction band, It is the first sub-energy level of the valence band top hole.

[0059] The following formula is satisfied for quantum well strain:

[0060] in, is the effective band gap of the compressive strain quantum well, the band gap from the first sub-energy level of the conduction band to the first sub-energy level of the heavy hole band, is the band gap of the quantum well in the absence of strain, which is related to the material composition and content. is the conduction band deformation potential of the quantum well, is the deformation potential of the valence and conduction bands of the quantum well, For the cutting edge shape change, and is the elastic modulus, Therefore, when designing the epitaxial structure 100, the band gap of the quantum well layer 15 is first designed according to the target wavelength, and then the matching design of the barrier, waveguide and confinement layer is performed.

[0061] According to the design method of the present application, all achievable bands of GaAs semiconductor lasers can be used. The specific structure can achieve similar effects by changing or fine-tuning the band gap of the quantum well structure corresponding to the working wavelength. Therefore, the following Table 3 gives an example of forming a 950nm band on an N-type GaAs substrate for reference. The specific structural information is as follows: Table 3 is an example of the change of the content of each element in the 950nm band formed on an N-type GaAs substrate and the change of the band difference

[0062] The epitaxial structure can also be formed on a P-type GaAs substrate, and a buffer layer can be formed before forming the epitaxial structure on the substrate. When the above epitaxial structure is formed on a P-type substrate, the first confinement layer is a P-type confinement layer, and the Al x11 Ga 1-x11 As, 0.35≤x11≤0.90; the first waveguide layer is a P-type waveguide layer Al x12 Ga 1-x12 As, 0.20≤x12≤0.30; the first blocking layer is an electron blocking layer Al x13 Ga y13 In 1-x13-y13 As, 1-x13-y13<0.2, 0.25≤x13≤0.45; the first barrier layer is a P-type barrier layer Al x14 Ga 1-x14 As, 0.05≤x14≤0.15; quantum well layer is In x15 Ga 1-x15 As, 0≤x15≤0.25; the second barrier layer is an N-type barrier layer, Al x16 Ga 1-x16As, 0.05≤x16≤0.15; the second blocking layer is a hole blocking layer, Ga x17 In 1-x17 P, x17≥0.55; the second waveguide layer is an N-type waveguide layer, Al x18 Ga 1-x18 As, 0.2≤x18≤0.4; the second limiting layer is an N-type limiting layer Al x19 Ga 1-x19 As, 0.25≤x19≤0.80.

[0063] In another embodiment of the present application, Figure 3 The N-type epitaxial structure 100 is formed on an InP substrate, and the energy band diagram of the epitaxial structure is shown. The N-type epitaxial structure 100 includes: the first confinement layer is an InP material, the first waveguide layer is an AlGaInAs material, the first barrier layer is a GaInP material, the first barrier layer is an AlGaInAs material, the quantum well layer is an AlGaInAs material, the second barrier layer is an AlGaInAs material, the second waveguide layer is an AlGaInAs material, and the second confinement layer is an InP material. The material combination in the above embodiment is only a typical and practically executable preferred combination. In other embodiments, the material combination may be variable.

[0064] In one embodiment, the first waveguide layer is Al m1 Ga n1 In 1-m1-n1 As, 0.25≤m1≤0.45, 0.05≤n1≤0.20; specifically, m1=0.4, n1=0.09 can be set. The first barrier layer is Ga m2 In 1-m2 P, 0.60≤m2≤0.85; m2=0.69 can be set specifically. The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25; specifically, m3=0.35, n3=0.27. The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25; specifically, m5=0.32, n5=0.18. The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60; m6=0.58 can be set specifically. The second waveguide layer is Al m7 Gan7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20; specifically, m7=0.40, n7=0.19 can be set. The quantum well layer is Al m4 Ga n4 In 1-m4-n4 As, 0.02≤m4≤0.10, 0.30≤n4≤0.50; specifically, m4=0.07, n4=0.42. Both the first confinement layer and the second confinement layer are InP.

[0065] In one embodiment, the thickness of the first confinement layer is 1.5-3 microns, the thickness of the first waveguide layer is 0.3-1.5 microns, the thickness of the first barrier layer is 0.004-0.030 microns, the thickness of the first barrier layer is 0.003-0.060 microns, the thickness of the quantum well layer is 0.006-0.012 microns, the thickness of the second barrier layer is 0.003-0.060 microns, the thickness of the second barrier layer is 0.004-0.030 microns, the thickness of the second waveguide layer is 0.1-1.0 microns, and the thickness of the second confinement layer is 0.5-2.5 microns.

[0066] In a specific embodiment, an example of forming a 1480 nm band on an N-type InP substrate is given as shown in Table 4 below for reference, and the specific structural information is as follows: Table 4 is an example of the change of the content of each element in the 1480nm band formed on an N-type InP substrate and the change of the energy band difference

[0067] The present application also provides a method for preparing an epitaxial structure of a semiconductor laser.

[0068] The growth sources used in the epitaxial growth process include: Group III high-purity metal organic compound sources: trimethyl gallium (TMGa), trimethyl aluminum (TMAl) and trimethyl indium (TMIn); Group V high-purity metal organic compound sources: arsine (AsH 3 ) and phosphine (PH 3 ); doping sources: (di)silane (used to form N-type doping) and tetrabromomethane (CBr 4 ) (used to form P-type doping).

[0069] S1. Provide a substrate 1, and form a buffer layer 10 on the substrate 1. The material of the substrate 1 is GaAs or InP. The buffer layer is formed on the substrate, and the buffer layer can buffer the stress between the substrate and the upper layer structure, improve the lattice matching degree, and improve the connection performance between the substrate and the epitaxial structure of the semiconductor laser.

[0070] S2, forming a first confinement layer 11 on the buffer layer by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy. The first confinement layer 11 is Al x1 Ga 1-x1 In one embodiment, the first confinement layer 11 is an N-type confinement layer, using TMAl source, TMGa source and AsH 3 Source growth, wherein the Al content ranges from 0.25 to 0.80, that is, 0.25≤x1≤0.80, the growth thickness is controlled at 1.5 to 3.0 μm, and the growth rate is 0.1 to 1.0 nm / s.

[0071] S3, using TMAl source, TMGa source and AsH 3 A first waveguide layer 12 is formed on the first limiting layer 11. The material of the first waveguide layer 12 is Al x2 Ga 1-x2 As, wherein the content of Al is in the range of 0.20-0.30, the growth thickness is controlled at 0.5-1.5 μm, and the growth rate is 0.1-0.7 nm / s. In a specific embodiment, the first waveguide layer 12 is Al 0.2 Ga 0.8 As, the temperature for growing the first waveguide layer 12 is 680°C-750°C, preferably in the range of 700°C-710°C.

[0072] S4, in the same deposition chamber, using TMIn source, TMGa source and PH 3 The first barrier layer 13 (hole barrier layer) is epitaxially grown on the first waveguide layer 12. The material of the first barrier layer 13 (hole barrier layer) is GaInP, wherein the content of In is greater than or equal to 0.55, the growth thickness is controlled at 0.004μm~0.030μm, and the growth rate is 0.02~0.1nm / s. Since the first barrier layer 13 (hole barrier layer) contains In, In will precipitate at high temperature, and the precipitated In will form a p-type confinement layer of In material at the interface, which affects the performance of the semiconductor laser. Therefore, when forming the first barrier layer 13 (hole barrier layer), the temperature must be strictly controlled, and the growth temperature must be controlled at about 600°C, such as between 580°C-640°C, so as to prevent In precipitation.

[0073] After the first blocking layer 13 (hole blocking layer) is formed, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged. This ensures that after the first blocking layer 13 (hole blocking layer) is formed, even if a small amount of In is precipitated, it will not mix with the first waveguide layer 12 to form a layer structure.

[0074] In this step, the growth temperature and interface switching conditions of the first blocking layer 13 (hole blocking layer) are strictly controlled to ensure the steepness of the interface and the quality of the material.

[0075] S5, using TMAl source, TMGa source and AsH 3 A first barrier layer 14 is formed on the first barrier layer 13 (hole blocking layer). The material of the first barrier layer 14 is In x4 Ga 1-x4 As, wherein the content of Al is in the range of 0.05-0.20, the growth thickness is controlled in the range of 0.003-0.060 μm, and the growth rate is 0.02-0.1 nm / s. The growth temperature of the first barrier layer 14 is selected to be 680° C.-750° C.

[0076] S6. After forming the first barrier layer 14, the deposition temperature in the chamber is controlled to decrease to 580-640°C, and the quantum well layer 15 is deposited in this range. 3 The source grows a quantum well layer 15 on the first barrier layer 14. The material of the quantum well layer 15 is Inx5Ga1-x5As, in which the In content is about 0.12, the growth thickness is controlled at 0.006~0.01μm, and the growth rate is 0.02~0.1nm / s. Since the quantum well layer 15 is a material containing In, the temperature is lower than that of the deposition of the material not containing In to prevent the precipitation of In. After the quantum well layer 15 is formed, the reaction source is stopped and the temperature is kept unchanged. The time for stopping the introduction is 15-20 seconds.

[0077] S7, using TMAl source, TMGa source and AsH 3 The source forms a second barrier layer 16 above the quantum well 15. The material of the second barrier layer 16 is AlGaAs, wherein the Al content ranges from 0.05 to 0.20, the growth thickness is controlled to be 0.003 to 0.060 μm, and the growth rate is 0.02 to 0.1 nm / s. The second barrier layer 16 does not contain In, and is the same material as the first waveguide layer 12, and the growth temperature is selected to be 680°C-750°C. When forming the second barrier layer 16, the range of x6 is between 0.05 and 0.20.

[0078] S8, control the temperature in the chamber to decrease to 580℃-640℃, and use TMIn source, TMAl source, TMGa source and AsH 3The second barrier layer 16 is grown on the second barrier layer 16 by a gas source. The material of the second barrier layer 17 (electron blocking layer) is AlGaInAs, wherein the content of In is within 0.20, the growth thickness is controlled at 0.004-0.020 μm, and the growth rate is 0.02-0.1 nm / s. After the second barrier layer 17 (electron blocking layer) is formed, the gas source is stopped, and the injection stop time is 15-20 seconds. Stopping the injection of the gas source for a period of time can ensure that even if In is precipitated, it will not form a mixed layer structure with the layer structure above.

[0079] S9, increase the temperature, use TMAl source, TMGa source and AsH 3 The second waveguide layer 18 is formed on the second blocking layer 17 (electron blocking layer). The material of the second waveguide layer 18 is AlGaAs, the Al content ranges from 0.20 to 0.30, the growth thickness is controlled at 0.3 to 1.0 μm, and the growth rate is 0.1 to 0.7 nm / s. For example, the second waveguide layer 18 can be Al 0.2 Ga 0.8 The temperature for growing the second waveguide layer 18 is in the range of 680°C to 750°C, preferably in the range of 700°C to 710°C.

[0080] S10, using TMAl source, TMGa source and AsH 3 A second confinement layer 19 is grown on the second waveguide layer 18. The second confinement layer 19 is AlGaAs, wherein the Al content ranges from 0.35 to 0.80, the growth thickness is controlled to be 0.5 to 2.0 μm, and the growth rate is 0.1 to 1.0 nm / s. The growth temperature of the second confinement layer 19 can be controlled to be the same as the growth temperature of the second waveguide layer 18. The material composition ratio of the second confinement layer 19 is controlled by controlling the amount of the reaction source gas introduced. In a specific embodiment, the second confinement layer 19 is AlGaAs. 0.4 Ga 0.6 As.

[0081] S11, using TMGa source and AsH 3 The source forms a cap layer 20 on the second confinement layer 19. The cap layer 20 is GaAs. The growth thickness of the cap layer 20 is 0.01 μm to 0.04 μm, and the growth rate is 0.1 to 0.5 nm / s.

[0082] The above preparation method of the present application has the following advantages: (1) The reduction of Al content in the first barrier layer 14 and the second barrier layer 16 on both sides of the quantum well layer 15 (the Al content is between 0.05-0.15) leads to a reduction in the In content in the carrier blocking layer 13 (the In content in the first blocking layer, i.e., the hole blocking layer, is ≤0.45, and the In content in the second blocking layer 17 and the electron blocking layer is <0.20), which can greatly reduce the difficulty of epitaxial growth.

[0083] (2) By reducing the Al content in the first barrier layer 14 and the second barrier layer 16 on both sides of the quantum well layer 15, the valence band potential of the second barrier layer 16 on the side of the second barrier layer 17 (electron blocking layer) can be made smaller than the valence band potential of the second waveguide layer 18; the conduction band potential of the first barrier layer 14 on the side of the first barrier layer 13 (hole blocking layer) is smaller than the conduction band potential of the first waveguide layer 12; thereby, the blocking effect of the second barrier layer 17 (electron blocking layer) on holes can be reduced to a very low level or even eliminated, and the blocking effect of the first barrier layer 13 (hole blocking layer) on electrons can be reduced to a very low level or even eliminated, which can effectively improve the carrier injection efficiency and carrier confinement capability.

[0084] (3) The reduction of Al content in the first barrier layer 14 and the second barrier layer 16 on both sides of the quantum well layer 15 will reduce the series resistance of the overall epitaxial structure design, and can achieve a smaller voltage (here, a smaller voltage means that the voltage under the same current is reduced. Specifically, refer to the formula: V = V 0 +I*R s , where V 0 is the turn-on voltage, R s is the series resistance. Under the same current I, the series resistance R s becomes smaller, the voltage V decreases), achieving higher photoelectric conversion efficiency.

[0085] (4) The formation temperature of the second barrier layer 17 (electron barrier layer) and the first barrier layer 13 (hole barrier layer) containing indium, as well as the quantum well layer 15, is lower than that of other layers, so as to prevent the precipitation of In. After the formation of these three-layer structures, it is necessary to control the introduction of the reaction source, with a certain period of interruption time, and keep the temperature constant, so as to prevent the precipitation of In from affecting the upper layer structure and forming a mixed structure with the upper layer structure.

[0086] In another embodiment of the present application, the substrate 1 is InP, and a method for preparing an epitaxial structure of a semiconductor laser is provided, comprising sequentially growing a buffer layer 10, a first confinement layer 11, a first waveguide layer 12, a first barrier layer 13, a first barrier layer 14, a quantum well layer 15, a second barrier layer 16, a second barrier layer 17, a second waveguide layer 18, a second confinement layer 19, and a cap layer 20 on the InP substrate.

[0087] In growing the first waveguide layer Al m1 Ga n1 In 1-m1-n1 When As is added, the growth thickness is controlled at 0.3~1.5μm, and the growth rate is 0.05~0.8nm / s, wherein the content ranges of Al and Ga satisfy: 0.25≤m1≤0.45, 0.05≤n1≤0.20.

[0088] In growing the first barrier layer Ga m2 In 1-m2 When P, the growth thickness is controlled at 0.004μm~0.030μm, the growth rate is 0.02~0.8nm / s, and the In content range satisfies: 0.60≤m2≤0.85; After the growth of the first barrier layer is completed, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged.

[0089] When growing the first barrier layer Al m3 Ga n3 In 1-m3-n3 When As is used, the growth thickness is controlled at 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s, wherein the content ranges of Al and Ga satisfy: 0.20≤m3≤0.40, 0.10≤n3≤0.25. When forming the first barrier layer, the growth temperature is selected to be 630℃-750℃, the growth thickness is controlled at 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s.

[0090] In the quantum well layer Al m4 Ga n4 In 1-m4-n4 During As deposition, the deposition temperature in the chamber is controlled to drop to 580-700°C, the growth thickness is controlled to be 0.006-0.012μm, and the growth rate is 0.02-0.1nm / s, wherein the contents of Al and Ga satisfy: 0.02≤m4≤0.10, 0.30≤n4≤0.50; after the quantum well layer is formed, the reaction source is stopped for 15-20 seconds to keep the temperature unchanged.

[0091] When growing the second barrier layer Al m5 Ga n5 In 1-m5-n5 When As is used, the growth thickness is controlled at 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s, wherein the content ranges of Al and Ga satisfy: 0.20≤m5≤0.40, 0.10≤n5≤0.25. When forming the second barrier layer, the growth temperature is selected to be 630℃-750℃, the growth thickness is controlled at 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s.

[0092] In growing the second barrier layer Al m6 In 1-m6 When As is used, the growth thickness is controlled at 0.004μm~0.030μm, the growth rate is 0.02~0.8nm / s, and the Al content range satisfies: 0.45≤m6≤0.60; after the growth of the second barrier layer is completed, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged.

[0093] In growing the second waveguide layer Al m7 Ga n7 In 1-m7-n7 When As is added, the growth thickness is controlled at 0.1~1.0μm, the growth rate is 0.05~0.8nm / s, and the content ranges of Al and Ga satisfy: 0.35≤m7≤0.50, 0.10≤n7≤0.20.

[0094] The present application also relates to a semiconductor laser, comprising a substrate 1 and an epitaxial structure 100 disposed on the surface of the substrate. The epitaxial structure 100 is the epitaxial structure 100 as described in any of the above embodiments, or an epitaxial structure obtained by any of the above methods for preparing the epitaxial structure 100.

[0095] The epitaxial structure of the semiconductor laser and the semiconductor laser involved in the present application adjust the contents of aluminum and gallium in the first waveguide layer 12, the first barrier layer 14, the second barrier layer 16 and the second waveguide layer 18, adjust the contents of gallium and indium in the first blocking layer 13 (hole blocking layer), and adjust the contents of aluminum, gallium and indium in the second blocking layer 17 (electron blocking layer), so that the first conduction band difference ΔEc11 between the second blocking layer 17 (electron blocking layer) and the second barrier layer 16 is greater than 70 meV, the second valence band difference ΔEv21 between the first blocking layer 13 (hole blocking layer) and the first barrier layer 14 is greater than 240 meV, the first valence band difference ΔEv11 between the second blocking layer 17 (electron blocking layer) and the second waveguide layer 18 is equal to a meV, and the second conduction band difference ΔEc21 between the first blocking layer 13 (hole blocking layer) and the first waveguide layer 12 is equal to b meV, wherein a≤0 and b≤0.

[0096] The inventors found that the differences in polarization intensity, lattice matching and doping efficiency of the material system determine the completely different EBL design logic. The traditional GaN-based EBL (electron blocking layer) is a necessary means to make up for the shortcomings of the material, while the epitaxial structure of the semiconductor laser involved in this application and the GaAs-based EBL (electron blocking layer) used in the semiconductor laser may become a redundant design in terms of performance and cost.

[0097] GaN materials (especially InGaN quantum wells) have significant lattice mismatch and piezoelectric polarization effects, which lead to quantum well band tilting, and electrons easily leak from the active region to the p-type layer. At the same time, the p-type doping efficiency in GaN is low, the hole mobility is much lower than that of electrons, and the hole injection efficiency is low. In order to overcome the strong polarization effect and hole injection barrier of InGaN / GaN quantum wells, GaN-based laser chips must adopt an electron blocking layer (EBL) structure (such as p-AlGaN layer) to block electron leakage through high conduction band barriers. There is no need to consider reducing the blocking of holes by the electron blocking layer to an extremely low level during design. The band gradient can be adjusted by optimizing the composition, thickness and doping design of the p-type transition compensation layer and the electron blocking layer (p-AlGaN layer) to improve the hole injection efficiency.

[0098] The GaAs-based structure involved in this application naturally forms a high potential barrier through the band offset of the heterojunction (such as the increase of Al components greatly increases the conduction band and valence band offset), which can effectively limit carriers, and the polarization electric field is weak, the quantum well band is flat, and the leakage risk is low. At the same time, the p-type GaAs has a high doping efficiency, the hole mobility is much better than GaN, the hole injection is more sufficient, and the electron-hole asymmetry problem is not significant. Therefore, when using the electron / hole blocking layer design in the GaAs-based structure, it is necessary to additionally solve the defects caused by lattice mismatch, the reduction of hole injection efficiency and doping compatibility problems. When designing the electron blocking layer, it is necessary to reduce the blocking effect of the layer on holes to a very low level (<20meV). Therefore, reducing the blocking effect of the electron blocking layer on holes and reducing the blocking effect of the hole blocking layer on electrons are the key to the design of GaAs-based EBL.

[0099] In addition, the material combinations of GaN-based structures and GaAs-based structures are also different. The material combination of GaN-based structures: QW+InGaN waveguide layer+AlGaN EBL+ AlGaN confinement layer; the material combination of GaAs-based structures: QW+AlGaAs waveguide layer+InAlGaAs EBL+ AlGaAs waveguide layer+ AlGaAs confinement layer.

[0100] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0101] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An epitaxial structure of a semiconductor laser, comprising: The first waveguide layer, the first blocking layer, the first barrier layer, the quantum well layer, the second barrier layer, the second blocking layer, and the second waveguide layer are stacked from bottom to top, characterized in that: A first conduction band difference ΔEc11 between the second blocking layer and the second barrier layer is greater than 70 meV, a second valence band difference ΔEv21 between the first blocking layer and the first barrier layer is greater than 240 meV, a first valence band difference ΔEv11 between the second blocking layer and the second waveguide layer is equal to a meV, and a second conduction band difference ΔEc21 between the first blocking layer and the first waveguide layer is equal to b meV, wherein a≤0, b≤0.

2. The epitaxial structure of a semiconductor laser according to claim 1, characterized in that: The content of aluminum in the first waveguide layer is greater than that in the first barrier layer; and the content of aluminum in the second waveguide layer is greater than that in the second barrier layer.

3. The epitaxial structure of a semiconductor laser according to claim 2, characterized in that: The first waveguide layer is Al x2 Ga 1-x2 As, 0.2≤x2≤0.4; The first barrier layer is Ga x3 In 1-x3 P, x3 ≥ 0.55; The first barrier layer is Al x4 Ga 1-x4 As, 0.05≤x4≤0.20; The second barrier layer is Al x6 Ga 1-x6 As, 0.05≤x6≤0.20; The second barrier layer is Al x7 Ga y7 In 1-x7-y7 As, 1-x7-y7<0.2, 0.25≤x7≤0.45; The second waveguide layer is Al x8 Ga 1-x8 As, 0.20≤x8≤0.

30.

4. The epitaxial structure of a semiconductor laser according to claim 3, characterized in that: The epitaxial structure of the semiconductor laser further includes: a first confinement layer disposed below the first waveguide layer and a second confinement layer disposed above the second waveguide layer; The first confinement layer is Al x1 Ga 1-x1 As, 0.25≤x1≤0.80; The quantum well layer is In x5 Ga 1-x5 As, 0≤x5≤0.25; The second confinement layer is Al x9 Ga 1-x9 As, 0.35≤x9≤0.

90.

5. The epitaxial structure of a semiconductor laser according to claim 4, characterized in that: The thickness of the first limiting layer is 1.5-3 microns, the thickness of the first waveguide layer is 0.3-1.5 microns, the thickness of the first barrier layer is 0.004-0.030 microns, the thickness of the first barrier layer is 0.003-0.060 microns, the thickness of the quantum well layer is 0.006-0.010 microns, the thickness of the second barrier layer is 0.003-0.060 microns, the thickness of the second barrier layer is 0.004-0.030 microns, the thickness of the second waveguide layer is 0.3-1.0 microns, and the thickness of the second limiting layer is 0.5-2 microns.

6. The epitaxial structure of a semiconductor laser according to claim 2, characterized in that: The first waveguide layer is Al m1 Ga n1 In 1-m1-n1 As, 0.25≤m1≤0.45, 0.05≤n1≤0.20; The first barrier layer is Ga m2 In 1-m2 P, 0.60≤m2≤0.85; The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25; The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25; The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60; The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.

20.

7. The epitaxial structure of a semiconductor laser according to claim 6, characterized in that: The epitaxial structure of the semiconductor laser further includes: a first confinement layer disposed below the first waveguide layer and a second confinement layer disposed above the second waveguide layer; The quantum well layer is Al m4 Ga n4 In 1-m4-n4 As, 0.02≤m4≤0.10, 0.30≤n4≤0.50; The first confinement layer and the second confinement layer are both InP.

8. The epitaxial structure of a semiconductor laser according to claim 7, characterized in that: The thickness of the first limiting layer is 1.5-3 microns, the thickness of the first waveguide layer is 0.3-1.5 microns, the thickness of the first barrier layer is 0.004-0.030 microns, the thickness of the first barrier layer is 0.003-0.060 microns, the thickness of the quantum well layer is 0.006-0.012 microns, the thickness of the second barrier layer is 0.003-0.060 microns, the thickness of the second barrier layer is 0.004-0.030 microns, the thickness of the second waveguide layer is 0.1-1.0 microns, and the thickness of the second limiting layer is 0.5-2.5 microns.

9. A method for preparing an epitaxial structure of a semiconductor laser, characterized in that: include: Growing a first waveguide layer, a first blocking layer, a first potential barrier layer, a quantum well layer, a second potential barrier layer, a second blocking layer, and a second waveguide layer in a stacked manner on a substrate; During the growth of the first waveguide layer, the first barrier layer, the first barrier layer, the second barrier layer, the second barrier layer and the second waveguide layer: adjusting the contents of aluminum and gallium in the first waveguide layer, adjusting the contents of gallium and indium in the first barrier layer, and adjusting the contents of aluminum and indium in the second barrier layer, so that a first conduction band difference ΔEc11 between the second barrier layer and the second barrier layer is greater than 70 meV, a second valence band difference ΔEv21 between the first barrier layer and the first barrier layer is greater than 240 meV, a first valence band difference ΔEv11 between the second barrier layer and the second waveguide layer is equal to meV, and a second conduction band difference ΔEc21 between the first barrier layer and the first waveguide layer is equal to b meV, where a≤0 and b≤0.

10. The method for preparing an epitaxial structure of a semiconductor laser according to claim 9, characterized in that: The epitaxial structure of the semiconductor laser further includes: a first confinement layer disposed below the first waveguide layer and a second confinement layer disposed above the second waveguide layer; The first confinement layer is made of AlGaAs material; The first waveguide layer is made of AlGaAs material; The first barrier layer is made of GaInP material; The first barrier layer is made of AlGaAs material; The quantum well layer is made of InGaAs material; The second barrier layer is made of AlGaAs material; The second barrier layer is made of AlGaInAs material; The second waveguide layer is made of AlGaAs material; The second confinement layer is made of AlGaAs material.

11. The method for preparing an epitaxial structure of a semiconductor laser according to claim 10, characterized in that: In growing the first waveguide layer Al x2 Ga 1-x2 When As, the growth thickness is controlled at 0.5~1.5μm, the growth rate is 0.1~0.7nm / s, and the Al content range satisfies: 0.2≤x2≤0.4; When growing the first barrier layer Al x 4Ga 1-x4 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.1nm / s, and the Al content range satisfies: 0.05≤x4≤0.20; When growing the second barrier layer Al x6 Ga 1-x6 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.1nm / s, and the Al content range satisfies: 0.05≤x6≤0.20; In growing the second waveguide layer Al x8 Ga 1-x8 When As is added, the growth thickness is controlled at 0.3~1.0μm, the growth rate is 0.1~0.7nm / s, and the Al content range satisfies: 0.20≤x8≤0.

30.

12. The method for preparing an epitaxial structure of a semiconductor laser according to claim 11, characterized in that: include: In growing the first barrier layer Ga x3 In 1-x3 When P, the growth thickness is controlled at 0.004 μm~0.020 μm, the growth rate is 0.02~0.1 nm / s, and the In content range satisfies: x3≥0.55; after the first barrier layer is grown, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged; as well as, In growing the second barrier layer Al x7 Ga y7 In 1-x7-y7 As, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.1 nm / s, and the In content range satisfies: 1-x7-y7<0.2; the second barrier layer Al x7 Ga y7 In 1-x7-y7 After the As growth is completed, stop injecting the reaction source for 15-20 seconds to keep the temperature in the chamber constant.

13. The method for preparing an epitaxial structure of a semiconductor laser according to claim 11, characterized in that: include: When forming the first barrier layer, the growth temperature is selected to be 680° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.1 nm / s; When forming the second barrier layer, the growth temperature is selected to be 680° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.1 nm / s.

14. The method for preparing an epitaxial structure of a semiconductor laser according to claim 11, characterized in that: In the quantum well layer x5 Ga 1-x5 During As deposition, the deposition temperature in the chamber is controlled to be lowered to 580-640°C, the growth thickness is controlled to be 0.006-0.01 μm, the growth rate is 0.02-0.1 nm / s, and the In content satisfies: 0≤x5≤0.25; After the quantum well layer is formed, the reaction source is stopped for 15-20 seconds to keep the temperature constant.

15. The method for preparing an epitaxial structure of a semiconductor laser according to claim 9, characterized in that: The epitaxial structure of the semiconductor laser further includes: a first confinement layer disposed below the first waveguide layer and a second confinement layer disposed above the second waveguide layer; The first waveguide layer is Al m1 Ga n1 In 1-m1-n1 As, 0.25≤m1≤0.45, 0.05≤n1≤0.20; The first barrier layer is Ga m2 In 1-m2 P, 0.60≤m2≤0.85; The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25; The quantum well layer is Al m4 Ga n4 In 1-m4-n4 As, 0.02≤m4≤0.10, 0.30≤n4≤0.50; The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25; The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60; The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20; The first confinement layer and the second confinement layer are both InP.

16. The method for preparing an epitaxial structure of a semiconductor laser according to claim 15, characterized in that: In growing the first waveguide layer Al m1 Ga n1 In 1-m1-n1 When As, the growth thickness is controlled at 0.3~1.5μm, the growth rate is 0.05~0.8nm / s, and the content range of Al and Ga satisfies: 0.25≤m1≤0.45, 0.05≤n1≤0.20; In growing the first barrier layer Ga m2 In 1-m2 When P, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.8 nm / s, and the In content range satisfies: 0.60≤m2≤0.85; After the growth of the first barrier layer is completed, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged; When growing the first barrier layer Al m3 Ga n3 In 1-m3-n3 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.8nm / s, and the content range of Al and Ga satisfies: 0.20≤m3≤0.40, 0.10≤n3≤0.25; In the quantum well layer Al m4 Ga n4 In 1-m4-n4 During As deposition, the deposition temperature in the chamber is controlled to be lowered to 580-700°C, the growth thickness is controlled to be 0.006-0.012 μm, the growth rate is 0.02-0.1 nm / s, and the contents of Al and Ga satisfy the following conditions: 0.02≤m4≤0.10, 0.30≤n4≤0.50; after the quantum well layer is formed, the reaction source is stopped for 15-20 seconds to keep the temperature constant; When growing the second barrier layer Al m5 Ga n5 In 1-m5-n5 When As, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.8nm / s, and the content range of Al and Ga satisfies: 0.20≤m5≤0.40, 0.10≤n5≤0.25; In growing the second barrier layer Al m6 In 1-m6 When As, the growth thickness is controlled at 0.004 μm~0.030 μm, the growth rate is 0.02~0.8 nm / s, and the Al content range satisfies: 0.45≤m6≤0.60; after the second barrier layer is grown, the injection of the reaction source is stopped for 15-20 seconds to keep the temperature in the chamber unchanged; In growing the second waveguide layer Al m7 Ga n7 In 1-m7-n7 When As is added, the growth thickness is controlled at 0.1~1.0μm, the growth rate is 0.05~0.8nm / s, and the content ranges of Al and Ga satisfy: 0.35≤m7≤0.50, 0.10≤n7≤0.

20.

17. The method for preparing an epitaxial structure of a semiconductor laser according to claim 16, characterized in that: include: When forming the first barrier layer, the growth temperature is selected to be 630° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s; When forming the second barrier layer, the growth temperature is selected to be 630° C.-750° C., the growth thickness is controlled to be 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s.

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