Epitaxial structure of semiconductor laser and preparation method thereof

Abstract

The present application provides an epitaxial structure of a semiconductor laser and a preparation method thereof. The epitaxial structure includes: 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 stacked from bottom to top. By adjusting the different contents of aluminum and gallium in the first waveguide layer, the first barrier layer, the second barrier layer, and the second waveguide layer, adjusting the different contents of gallium and indium in the first barrier layer, and adjusting the different contents of aluminum, gallium, and indium in the second barrier layer, the first conduction band difference ΔEc11 is greater than 70meV, the second valence band difference ΔEv21 is greater than 240meV, and the first valence band difference ΔEv11 and the second conduction band difference ΔEc21 are both less than or equal to 0meV. The epitaxial structure can well balance the confinement effect on electrons and holes, so that the epitaxial structure has the best carrier confinement ability and improves the output efficiency of the device.

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 thin, high-bandgap carrier-blocking layer is inserted between low-bandgap waveguide layers to confine carriers (especially electrons) as much as possible within the quantum well. However, current adjustments to the epitaxial structure often result in insufficient carrier confinement, preventing significant improvements in semiconductor laser output efficiency. 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 restricting effects on electrons and holes, so that the carrier restriction capability of the epitaxial structure reaches an optimal state, and the output efficiency of the semiconductor laser is greatly improved; at the same time, the lattice matching between the layers of the epitaxial structure is good, which is suitable for large-scale and batch production.

[0004] The technical solutions provided in this application are as follows:

[0005] 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,

[0006] 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, where a≤0 and b≤0.

[0007] In one embodiment, the aluminum content in the first waveguide layer is greater than that in the first barrier layer; and the aluminum content in the second waveguide layer is greater than that in the second barrier layer.

[0008] In one embodiment, the first waveguide layer is Al x2 Ga 1-x2 As, 0.2≤x2≤0.4;

[0009] The first barrier layer is Ga x3 In 1-x3 P, x3 ≥ 0.55;

[0010] The first barrier layer is Al x4 Ga 1-x4 As, 0.05≤x4≤0.20;

[0011] The second barrier layer is Al x6 Ga 1-x6 As, 0.05≤x6≤0.20;

[0012] The second barrier layer is Al x7 Ga y7 In 1-x7-y7 As, 1-x7-y7<0.2, 0.25≤x7≤0.45;

[0013] The second waveguide layer is Al x8 Ga 1-x8 As, 0.20≤x8≤0.30.

[0014] In one embodiment, the first confinement layer is Al x1 Ga 1-x1 As, 0.25≤x1≤0.80;

[0015] The quantum well layer is In x5 Ga 1-x5 As, 0≤x5≤0.25;

[0016] The second confinement layer is Al x9 Ga 1-x9 As, 0.35≤x9≤0.90.

[0017] 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.

[0018] 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;

[0019] The first barrier layer is Ga m2 In1-m2 P, 0.60≤m2≤0.85;

[0020] The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25;

[0021] The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25;

[0022] The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60;

[0023] The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20.

[0024] 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;

[0025] The first confinement layer and the second confinement layer are both InP.

[0026] 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.

[0027] The present application provides a method for preparing an epitaxial structure of a semiconductor laser, comprising:

[0028] Growing a first waveguide layer, a first barrier layer, a first potential barrier layer, a quantum well layer, a second potential barrier layer, a second barrier layer, and a second waveguide layer in a stacked manner on a substrate;

[0029] 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 contents of gallium and indium in the first barrier layer, 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.

[0030] In one embodiment, the first confinement layer is made of AlGaAs material;

[0031] The first waveguide layer is made of AlGaAs material;

[0032] The first barrier layer is made of GaInP material;

[0033] The first barrier layer is made of AlGaAs material;

[0034] The quantum well layer is made of InGaAs material;

[0035] The second barrier layer is made of AlGaAs material;

[0036] The second barrier layer is made of AlGaInAs material;

[0037] The second waveguide layer is made of AlGaAs material;

[0038] The second confinement layer is made of AlGaAs material.

[0039] In one embodiment, the first waveguide layer Al is grown x2 Ga 1-x2 When As is used, 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;

[0040] When growing the first barrier layer Al x4 Ga 1-x4 When As is added, 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;

[0041] When growing the second barrier layer Alx6 Ga 1-x6 When As is used, 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;

[0042] In the growth of 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.

[0043] In one embodiment, the method includes:

[0044] In growing the first barrier layer Ga x3 In 1-x3 When P is used, the growth thickness is controlled to be 0.004 μm to 0.030 μm, the growth rate is 0.02 to 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, and the temperature in the chamber is kept constant;

[0045] as well as,

[0046] When growing the second barrier layer Al x7 Ga y7 In 1-x7-y7 When As is used, the growth thickness is controlled at 0.004 μm to 0.030 μm, the growth rate is 0.02 to 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 and keep the temperature in the chamber constant.

[0047] In one embodiment, the method includes:

[0048] 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;

[0049] 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.

[0050] In one embodiment, the quantum well layer In x5 Ga 1-x5During 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 the following conditions: 0≤x5≤0.25;

[0051] After the quantum well layer is formed, the reaction source is stopped for 15-20 seconds and the temperature is kept constant.

[0052] 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;

[0053] The first barrier layer is Ga m2 In 1-m2 P, 0.60≤m2≤0.85;

[0054] The first barrier layer is Al m3 Ga n3 In 1-m3-n3 As, 0.20≤m3≤0.40, 0.10≤n3≤0.25;

[0055] The quantum well layer is Al m4 Ga n4 In 1-m4-n4 As, 0.02≤m4≤0.10, 0.30≤n4≤0.50;

[0056] The second barrier layer is Al m5 Ga n5 In 1-m5-n5 As, 0.20≤m5≤0.40, 0.10≤n5≤0.25;

[0057] The second barrier layer is Al m6 In 1-m6 As, 0.45≤m6≤0.60;

[0058] The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20;

[0059] The first confinement layer and the second confinement layer are both InP.

[0060] In one embodiment, the first waveguide layer Al is grown m1 Ga n1 In 1-m1-n1When As is used, the growth thickness is controlled at 0.3~1.5μm, the growth rate is 0.05~0.8nm / s, and the Al and Ga content ranges meet the following requirements: 0.25≤m1≤0.45, 0.05≤n1≤0.20;

[0061] In growing the first barrier layer Ga m2 In 1-m2 When P is used, the growth thickness is controlled to be 0.004 μm to 0.030 μm, the growth rate is 0.02 to 0.8 nm / s, and the In content range satisfies: 0.60 ≤ m2 ≤ 0.85; after the first barrier layer is grown, the injection of the reaction source is stopped for 15-20 seconds, and the temperature in the chamber is kept constant;

[0062] When growing the first barrier layer Al m3 Ga n3 In 1-m3-n3 When As is used, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.8nm / s, and the Al and Ga content ranges meet the following requirements: 0.20≤m3≤0.40, 0.10≤n3≤0.25;

[0063] 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, and the growth rate is 0.02-0.1 nm / s. The Al and Ga contents 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, and the temperature is kept constant.

[0064] When growing the second barrier layer Al m5 Ga n5 In 1-m5-n5 When As is used, the growth thickness is controlled at 0.003~0.060μm, the growth rate is 0.02~0.8nm / s, and the Al and Ga content ranges meet the following requirements: 0.20≤m5≤0.40, 0.10≤n5≤0.25;

[0065] When growing the second barrier layer Al m6 In 1-m6 When As is grown, the growth thickness is controlled to be 0.004 μm to 0.030 μm, the growth rate is 0.02 to 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, and the temperature in the chamber is kept constant;

[0066] In the growth of the second waveguide layer Alm7 Ga n7 In 1-m7-n7 When As is used, 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.

[0067] In one embodiment, the method includes:

[0068] 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;

[0069] 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.

[0070] The epitaxial structure design of the semiconductor laser provided in this application can well balance the restriction effects on electrons and holes, so that the epitaxial structure's carrier restriction ability reaches an optimal state, 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), relying on the adjustment of the aluminum and gallium content in the first waveguide layer, the first barrier layer, the second barrier layer, and the second waveguide layer, can keep the indium element within an appropriate range, thereby achieving good lattice matching between the layers in the epitaxial structure, suitable for large-scale, 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. In particular, the output power and electro-optical conversion efficiency under high temperature power conditions will be greatly improved, greatly expanding the application direction of semiconductor lasers.

[0071] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without any creative work.

[0073] Figure 1 Schematic diagram of the energy band of a typical epitaxial structure with a carrier blocking layer;

[0074] Figure 2 A schematic diagram of the energy bands of an epitaxial structure provided in one embodiment of the present application;

[0075] Figure 3 A schematic diagram of the energy bands of an epitaxial structure provided in another embodiment of the present application;

[0076] Figure 4 An embodiment of the present application provides a substrate and a buffer layer, as well as an epitaxial structure of a semiconductor laser grown thereon.

[0077] Reference numerals:

[0078] 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,

[0079] Substrate 1, buffer layer 10,

[0080] Epitaxial structure 100 includes: a first confinement layer 11 , a first waveguide layer 12 , a first barrier layer 13 , a first potential barrier layer 14 , a quantum well layer 15 , a second potential 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

[0081] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. It should be noted that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein can be arranged and designed in a variety of 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 claimed application, but rather merely represents selected embodiments of the present application. All other embodiments derived by those skilled in the art based on the embodiments of the present application without inventive effort are within the scope of protection of this application. It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. In addition, in the description of this application, the terms "first," "second," etc. are used only to distinguish descriptions and should not be understood to indicate or imply relative importance.

[0082] Through a series of researches by the applicant, it is found that in the epitaxial structure design of semiconductor lasers, the band gap design of the typical GaAs / AlGaAs-based epitaxial structure with carrier blocking layer is as follows: Figure 1As 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. At the same time, the effect of quantum well strain on gain and growth quality should be considered to select 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.

[0083] like Figure 1 As shown, the typical epitaxial structure bandgap design with carrier blocking layers has two characteristics: the P-type electron blocking layer 07 restricts the movement of electrons in the N region to the P region, while also restricting 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, while also restricting 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 The purpose is 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.

[0084] In addition, the applicant of this application has found that in the process of adjusting the proportions of various elements in the epitaxial structure, one cannot simply pursue the band gap. It is also necessary 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, which cannot achieve a good matching state with the AlGaAs material, resulting in greater difficulty in growing the epitaxial material and is not conducive to large-scale, batch production.

[0085] Based on the above research conclusions, the applicant provides a Figure 2 、 Figure 3 and Figure 4The 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.

[0086] See also Figure 4 The epitaxial structure 100 can be formed on an N-type GaAs substrate or an InP substrate. 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 barrier layer 13 is a hole barrier layer, the first barrier layer 14 is an N-type barrier layer, the quantum well layer 15 and the second barrier layer 16 are P-type barrier layers, the second barrier 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.

[0087] In one embodiment, Figure 2 As shown, an N-type epitaxial structure 100 is formed on a GaAs substrate and includes a first confinement layer below the first waveguide layer and a second confinement layer above the second waveguide layer. The first confinement layer is made of AlGaAs, the first waveguide layer is made of AlGaAs, the first barrier layer is made of GaInP, the first barrier layer is made of AlGaAs, the quantum well layer is made of InGaAs, the second barrier layer is made of AlGaAs, the second barrier layer is made of AlGaInAs, the second waveguide layer is made of AlGaAs, and the second confinement layer is made of AlGaAs. The material combination in the above embodiment is merely a typical and practically feasible preferred combination. In other embodiments, the material combination may vary; for example, the quantum well structure may also be an InAlGaAs structure.

[0088] 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, where a≤0 and b≤0.

[0089] In this embodiment, by first adjusting the aluminum and gallium contents in the second barrier layer 16 and the second waveguide layer 18, and then adjusting the aluminum, gallium, and indium contents 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. At the same time, it can ensure that holes in the valence band can smoothly pass through the second blocking layer 17 (electron blocking layer) and enter the quantum well layer 15 (first valence band difference ΔEv11 ≈ 0). As shown in Table 1 below, the stronger electron-blocking effect is manifested in: 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, which is better than the first conduction band difference (ΔEc1 ≈ 60 meV) in the prior art.

[0090] Table 1 shows an example of the change of element content and band gap of the second barrier layer 16, the second blocking layer 17, and the second waveguide layer 18.

[0091]

[0092] Similarly, by first adjusting the aluminum and gallium contents in the first waveguide layer 12 and the first barrier layer 14, and then adjusting the gallium and indium contents in the first blocking layer 13 (hole blocking layer), a first blocking layer 13 (hole blocking layer) with a stronger hole-blocking effect can be obtained. At the same time, this ensures that electrons in the conduction band can smoothly pass through the first blocking layer 13 (hole blocking layer) and enter the quantum well layer 15 (i.e., ensuring a second conduction band difference ΔEc21 ≈ 0). As shown in Table 2 below, this stronger hole-blocking effect is manifested in: a second valence band difference ΔEv21 between the first blocking layer 13 (hole blocking layer) and the first barrier layer 14 greater than 240 meV, which is superior to the second valence band difference (ΔEv2 ≈ 200 meV) in the prior art.

[0093] Table 2 shows an example of the change of element content and band gap of the first waveguide layer 12, the first blocking layer 13, and the first barrier layer 14.

[0094]

[0095] Therefore, the epitaxial structure design of the semiconductor laser in the present application can well balance the confinement effects on electrons and holes, so that the epitaxial structure's carrier confinement ability reaches an optimal state, 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 maintain the gallium and indium elements within an appropriate 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, thereby ensuring good lattice matching between the layers in the epitaxial structure, making it 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. In particular, the output power and electro-optical conversion efficiency under high temperature power conditions will be significantly improved, greatly expanding the application direction of semiconductor lasers.

[0096] 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 .

[0097] In this embodiment, the aluminum content in the first waveguide layer 12 is greater than the aluminum content in the first barrier layer 14. This allows for adjusting the different contents of gallium and indium in the first barrier layer 13 (hole blocking layer). This facilitates designing a larger second valence band difference ΔEv21 between the first barrier layer 13 (hole blocking layer) and the first barrier layer 14 while ensuring that the second conduction band difference ΔEc21 between the first barrier layer 13 (hole blocking layer) and the first waveguide layer 12 is b meV, where b≤0.

[0098] Similarly, the aluminum content in the second waveguide layer 18 is greater than the aluminum content in the second barrier layer 16. This allows, when adjusting the contents of aluminum, gallium, and indium in the second blocking layer 17 (electron blocking layer), to design a larger first conduction band difference ΔEc11 between the second blocking layer 17 (electron blocking layer) and the second barrier layer 16 while ensuring that the first valence band difference ΔEv11 between the second blocking layer 17 (electron blocking layer) and the second waveguide layer 18 is ΔEv11=a meV, where a≤0.

[0099] In one embodiment, it can be more specifically configured that: the first waveguide layer 12 is 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 Ga 0.75 As, the second barrier layer 16 is Al 0.1 Ga 0.9 As.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] The reduction in the Al content in the first barrier layer 14 and the second barrier layer 16 leads to a reduction in the In content in the first blocking layer 13 (hole blocking layer) and the second blocking layer 17 (electron blocking layer). The reduction in In content facilitates the growth of epitaxial materials. Therefore, the epitaxial structure design in the embodiments of the present application can greatly reduce the difficulty of epitaxial growth.

[0107] 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 blocking layer) and the second barrier layer 17 (electron blocking layer) can achieve a higher band gap difference while having 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, while the growth tolerance is relatively large.

[0108] 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, which can achieve a lower voltage and 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 low 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 low 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.

[0109] In this embodiment, the above-mentioned value ranges have been verified by the applicant through epitaxial growth design, and are all able to balance the restriction effects on electrons and holes, so that the carrier restriction capability of the epitaxial structure reaches an 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 an appropriate range, and the lattice matching between the layers in the epitaxial structure is good, which is suitable for large-scale and batch production.

[0110] In one embodiment, the first confinement layer 11 is Al x1 Ga 1-x1As, 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 confinement layer 19 is Al x9 Ga 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.

[0111] 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.

[0112] 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.

[0113] In this application, the Al content (bandgap) in first confinement layer 11, first waveguide layer 12, second waveguide layer 18, and second confinement layer 19 varies synchronously with the quantum well layer 15 (wavelength, quantum well bandgap). Specifically, the quantum well bandgap Eg is negatively correlated with wavelength. Therefore, the longer the wavelength of the quantum well layer, the smaller the quantum well bandgap Eg. Consequently, the bandgap Eg of the corresponding waveguide layer and barrier layer also decreases, achieving an effective bandgap difference, reducing resistance, and achieving higher efficiency.

[0114] More specifically, the lasing wavelength of a semiconductor laser chip depends on the energy 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, the following conditions are met:

[0115]

[0116] 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 electron at the bottom of the conduction band, It is the first sub-energy level of the valence band top hole.

[0117] The following formula is satisfied for quantum well strain:

[0118]

[0119] 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 tangent shape transformation, 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.

[0120] According to the design method of the present application, all achievable wavelength 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 operating wavelength. Therefore, Table 3 below provides an example of forming a 950nm wavelength band on an N-type GaAs substrate for reference. The specific structural information is as follows:

[0121] Table 3 shows the changes in the content of each element in the 950nm band formed on an N-type GaAs substrate and the changes in the energy band difference.

[0122]

[0123] The epitaxial structure can also be formed on a P-type GaAs substrate. Before forming the epitaxial structure on the substrate, a buffer layer can be formed first. 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 Gay13 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-x16 As, 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.

[0124] In another embodiment of the present application, Figure 3 The following diagram illustrates an N-type epitaxial structure 100 formed on an InP substrate, showing an energy band diagram of the epitaxial structure. N-type epitaxial structure 100 includes: a first confinement layer made of InP material, a first waveguide layer made of AlGaInAs material, a first barrier layer made of GaInP material, a first barrier layer made of AlGaInAs material, a quantum well layer made of AlGaInAs material, a second barrier layer made of AlGaInAs material, a second waveguide layer made of AlGaInAs material, and a second confinement layer made of InP material. The material combination in the above embodiment is merely a typical and practically feasible preferred combination. In other embodiments, the material combination may vary.

[0125] 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; specifically, m2=0.69. The first barrier layer is Al m3 Ga n3 In 1-m3-n3As, 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; specifically, m6=0.58. The second waveguide layer is Al m7 Ga n7 In 1-m7-n7 As, 0.35≤m7≤0.50, 0.10≤n7≤0.20; specifically, m7=0.40, n7=0.19. 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.

[0126] 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.

[0127] In a specific embodiment, an example of forming a 1480 nm wavelength band on an N-type InP substrate is given in Table 4 below for reference. The specific structural information is as follows:

[0128] Table 4 shows the changes in the content of each element in the 1480nm band formed on an N-type InP substrate and the changes in the energy band difference.

[0129]

[0130] The present application also provides a method for preparing an epitaxial structure of a semiconductor laser.

[0131] The growth sources used in the epitaxial growth process include: Group III high-purity metal organic compound sources: trimethylgallium (TMGa), trimethylaluminum (TMAl) and trimethylindium (TMIn); Group V high-purity metal organic compound sources: arsine (AsH3) and phosphine (PH3); doping sources: (di)silane (used to form N-type doping) and tetrabromomethane (CBr4) (used to form P-type doping).

[0132] 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 formed on the substrate can buffer the stress between the substrate and the upper layer structure, improve the lattice matching degree, and enhance the connection performance between the substrate and the epitaxial structure of the semiconductor laser.

[0133] 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 grown using TMAl, TMGa, and AsH3 sources, wherein the Al content ranges from 0.25 to 0.80, i.e., 0.25 ≤ x1 ≤ 0.80, the growth thickness is controlled to be 1.5 to 3.0 μm, and the growth rate is 0.1 to 1.0 nm / s.

[0134] S3, using TMAl source, TMGa source and AsH3 source, form the first waveguide layer 12 on the first confinement 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.

[0135] S4. In the same deposition chamber, a TMIn source, a TMGa source, and a PH3 source are used to epitaxially grow a first barrier layer 13 (hole blocking layer) on the first waveguide layer 12. The material of the first barrier layer 13 (hole blocking layer) is GaInP, wherein the In content is greater than or equal to 0.55, the growth thickness is controlled to be 0.004μm to 0.030μm, and the growth rate is 0.02 to 0.1nm / s. Because the first barrier layer 13 (hole blocking layer) contains In, In will precipitate at high temperatures. The precipitated In will form a p-type confinement layer of In material at the interface, thus affecting the performance of the semiconductor laser. Therefore, when forming the first barrier layer 13 (hole blocking layer), the temperature must be strictly controlled. The growth temperature should be controlled at around 600°C, for example, between 580°C and 640°C, to prevent In precipitation.

[0136] After the first blocking layer 13 (hole blocking layer) is formed, the injection of the reaction source is stopped for 15-20 seconds and the temperature in the chamber is kept constant. This ensures that even if a small amount of In is precipitated after the first blocking layer 13 (hole blocking layer) is formed, it will not mix with the first waveguide layer 12 to form a layer structure.

[0137] 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.

[0138] S5, using TMAl source, TMGa source and AsH3 source, form the first barrier layer 14 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 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 growth temperature of the first barrier layer 14 is selected to be 680° C. to 750° C.

[0139] 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 within this range. A TMIn source, a TMGa source, and an AsH3 source are used to grow the 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 to be 0.006-0.01μm, and the growth rate is 0.02-0.1nm / s. Since the quantum well layer 15 is an In-containing material, the deposition temperature must be lower than that of the In-free material to prevent In precipitation. After the quantum well layer 15 is formed, the reaction source is stopped and the temperature is kept constant. The stopping time is 15-20 seconds.

[0140] In step S7, a second barrier layer 16 is formed above the quantum well 15 using a TMAl source, a TMGa source, and an AsH3 source. 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 made of the same material as the first waveguide layer 12. The growth temperature is selected to be 680°C to 750°C. During the formation of the second barrier layer 16, x6 ranges from 0.05 to 0.20.

[0141] S8. The temperature in the chamber is controlled to decrease to 580°C-640°C. A second blocking layer 17 (electron blocking layer) is grown on the second barrier layer 16 using a TMIn source, a TMAl source, a TMGa source, and an AsH3 source. The material of the second blocking layer 17 (electron blocking layer) is AlGaInAs, wherein the In content is within a range of 0.20, the growth thickness is controlled to be 0.004-0.020μm, and the growth rate is 0.02-0.1nm / s. After the second blocking layer 17 (electron blocking layer) is formed, the gas source is stopped, and the injection stop time is 15-20 seconds. Stopping the gas source injection for a period of time ensures that even if In is precipitated, it will not form a mixed layer structure with the layer structure above.

[0142] S9, raise the temperature, use TMAl source, TMGa source and AsH3 source to form the second waveguide layer 18 on the second blocking layer 17 (electron blocking layer). The material of the second waveguide layer 18 is AlGaAs, the Al content range is 0.20~0.30, the growth thickness is controlled at 0.3~1.0μm, and the growth rate is 0.1~0.7nm / 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.

[0143] S10, using TMAl source, TMGa source and AsH3 source, grow the second confinement layer 19 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.

[0144] S11. Using a TMGa source and an AsH3 source, a cap layer 20 is formed on the second confinement layer 19. The cap layer 20 is GaAs. The cap layer 20 has a thickness of 0.01 μm to 0.04 μm and a growth rate of 0.1 to 0.5 nm / s.

[0145] The above preparation method of the present application has the following advantages:

[0146] (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.

[0147] (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 will 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 will be reduced to a very low level or even eliminated, which can effectively improve the carrier injection efficiency and carrier confinement capability.

[0148] (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, the smaller voltage means that the voltage under the same current is reduced. Specifically, refer to the formula: V = V0 + I*R s , where V0 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.

[0149] (4) The formation temperature of the second blocking layer 17 (electron blocking layer) and the first blocking layer 13 (hole blocking 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. And 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 In from precipitating and not affecting the upper layer structure, and not forming a mixed structure with the layer structure formed above.

[0150] In another embodiment of the present application, the substrate 1 is InP, and a method for fabricating an epitaxial structure of a semiconductor laser is provided. The method includes 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.

[0151] During the growth of the first waveguide layer Al m1 Ga n1 In 1-m1-n1 When As is used, the growth thickness is controlled at 0.3~1.5μm, the growth rate is 0.05~0.8nm / s, and the content ranges of Al and Ga satisfy: 0.25≤m1≤0.45, 0.05≤n1≤0.20.

[0152] 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 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.

[0153] When growing the first barrier layer Al m3 Ga n3 In 1-m3-n3 When As is used, the growth thickness is controlled within a range of 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s. The Al and Ga content ranges satisfy the following conditions: 0.20≤m³≤0.40, and 0.10≤n³≤0.25. When forming the first barrier layer, the growth temperature is selected between 630°C and 750°C, the growth thickness is controlled within a range of 0.003-0.060 μm, and the growth rate is 0.02-0.8 nm / s.

[0154] 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 at 0.006-0.012 μm, and the growth rate is 0.02-0.1 nm / s, where the Al and Ga contents meet the following requirements: 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.

[0155] When growing the second barrier layer Al m5 Ga n5 In 1-m5-n5When forming As, the growth thickness is controlled between 0.003 and 0.060 μm, and the growth rate is 0.02 to 0.8 nm / s. The Al and Ga content ranges satisfy the following conditions: 0.20 ≤ m5 ≤ 0.40, and 0.10 ≤ n5 ≤ 0.25. When forming the second barrier layer, the growth temperature is selected between 630°C and 750°C, the growth thickness is controlled between 0.003 and 0.060 μm, and the growth rate is 0.02 to 0.8 nm / s.

[0156] When growing the second barrier layer Al m6 In 1-m6 When As is used, 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.

[0157] In the growth of the second waveguide layer Al m7 Ga n7 In 1-m7-n7 When As is used, 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.

[0158] 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 described in any of the above embodiments, or an epitaxial structure obtained by using any of the above methods for preparing the epitaxial structure 100.

[0159] 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, where a≤0 and b≤0.

[0160] The inventors discovered that differences in material polarization strength, lattice matching, and doping efficiency determine distinct EBL design logic. While traditional GaN-based EBLs are necessary to address material shortcomings, the epitaxial structure of the semiconductor laser and the GaAs-based EBLs employed in this application can become redundant in terms of performance and cost.

[0161] GaN materials (especially InGaN quantum wells) have significant lattice mismatch and piezoelectric polarization effects, which lead to quantum well band tilt and electrons easily leaking from the active region into 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. To overcome the strong polarization effect and hole injection barriers of InGaN / GaN quantum wells, GaN-based laser chips must adopt an electron blocking layer (EBL) structure (such as a p-AlGaN layer) to block electron leakage through a high conduction band barrier. During design, there is no need to consider reducing the electron blocking layer's blocking effect on holes to an extremely low level. The band gradient can be adjusted to improve the hole injection efficiency by optimizing the composition, thickness, and doping design of the p-type transition compensation layer and the electron blocking layer (p-AlGaN layer).

[0162] The GaAs-based structure involved in this application naturally forms a high potential barrier through the band offset of the heterojunction (for example, the increase in the Al component significantly 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 doping efficiency of p-type GaAs is high, the hole mobility is much better than that of 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 in hole injection efficiency and the doping compatibility problem. When designing the electron blocking layer, it is necessary to reduce the blocking effect of the layer on holes to an extremely 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.

[0163] In addition, the material combinations of GaN-based structures and GaAs-based structures are also different. The material combination of GaN-based structures is: QW + InGaN waveguide layer + AlGaN EBL + AlGaN confinement layer; the material combination of GaAs-based structures is: QW + AlGaAs waveguide layer + InAlGaAs EBL + AlGaAs waveguide layer + AlGaAs confinement layer.

[0164] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

[0165] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection 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, where a≤0 and b≤0; 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.

2. The epitaxial structure of the semiconductor laser according to claim 1, wherein: 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.

3. The epitaxial structure of the semiconductor laser according to claim 2, wherein: 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.

4. A method for preparing an epitaxial structure of a semiconductor laser, characterized in that: include: Growing a first waveguide layer, a first barrier layer, a first potential barrier layer, a quantum well layer, a second potential barrier layer, a second barrier 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, the first barrier layer, the second barrier layer, and the second 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; 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.

5. The method for preparing an epitaxial structure of a semiconductor laser according to claim 4, wherein: 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 quantum well layer is made of InGaAs material; The second confinement layer is made of AlGaAs material.

6. The method for preparing an epitaxial structure of a semiconductor laser according to claim 5, wherein: During the growth of the first waveguide layer Al x2 Ga 1-x2 When As is used, 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 is added, 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 is used, 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 the growth of 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.

7. The method for preparing an epitaxial structure of a semiconductor laser according to claim 6, wherein: include: In growing the first barrier layer Ga x3 In 1-x3 When P is used, the growth thickness is controlled to be 0.004 μm to 0.020 μm, and the growth rate is 0.02 to 0.1 nm / s, so that 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, and the temperature in the chamber is kept constant; as well as, When growing the second barrier layer Al x7 Ga y7 In 1-x7-y7 When As is used, the growth thickness is controlled at 0.004 μm to 0.030 μm, and the growth rate is 0.02 to 0.1 nm / s, so that 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 and keep the temperature in the chamber constant.

8. The method for preparing an epitaxial structure of a semiconductor laser according to claim 7, wherein: 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.

9. The method for preparing an epitaxial structure of a semiconductor laser according to claim 7, wherein: 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 the following conditions: 0≤x5≤0.25; After the quantum well layer is formed, the reaction source is stopped for 15-20 seconds and the temperature is kept constant.

Images