P-sch layer, cw laser epitaxial structure and preparation method thereof

Abstract

The application provides a P-SCH layer, a CW laser epitaxial structure and a preparation method thereof, and belongs to the field of semiconductors. The application provides a P-SCH layer, which is a multilayer structure, the number of layers of the multilayer structure is 2n, n is greater than or equal to 2, the emission wavelength increases from the first layer to the 2n layer; the difference between the emission wavelength of the n+1 layer and the emission wavelength of the n layer is 100-120 nm, and the difference between the emission wavelength of the remaining adjacent layers is 10-20 nm. The layer has a small span of two end emission wavelengths and a large span of middle emission wavelengths, a ladder structure, which greatly guarantees the electron leakage rate and the hole injection rate, thereby controlling the increase rate of the photon density with the increase of the current injection, and improving the device temperature stability.

Description

A P-SCH layer, CW laser epitaxial structure and its fabrication method Technical Field

[0001] This invention relates to the field of semiconductors, specifically to a P-SCH layer, a CW laser epitaxial structure, and its fabrication method. Background Technology

[0002] With the rapid development of 5G communication, cloud computing, and artificial intelligence technologies, global data traffic is growing exponentially, creating an increasingly urgent demand for high-power laser sources in high-speed optical interconnect systems. In the 1310nm optical communication band, CW lasers have become the core light source device for silicon photonics integrated systems due to their excellent single-mode characteristics (typical side-mode rejection ratio >50dB) and wavelength stability (temperature drift coefficient 0.08–0.12nm / ℃). However, in high-density optoelectronic co-packaging (CPO) applications, lasers face the problem of thermal accumulation: the thermal conductivity of traditional p-type confinement layers (P-SCH) is insufficient (typical value <50W / m·K), resulting in significant thermal saturation when the drive current is >80mA, leading to a power drop of >15%. Summary of the Invention

[0003] This invention provides a P-SCH layer, a CW laser epitaxial structure, and a method for fabricating the same. The P-SCH layer of this invention has good thermal conductivity.

[0004] This invention provides a P-SCH layer, which is a multi-layer structure with 2n layers, where n≥2, and the emission wavelength increases from the 1st layer to the 2nth layer.

[0005] The difference between the emission wavelength of the (n+1)th layer and the emission wavelength of the nth layer is 100-120 nm, and the difference between the emission wavelengths of the remaining adjacent layers is 10-20 nm.

[0006] Preferably, when n=2, the P-SCH layer consists of a first P-SCH layer, a second P-SCH layer, a third P-SCH layer, and a fourth P-SCH layer;

[0007] The thickness of the first P-SCH layer is 5±0.15nm, and the emission wavelength is 970±10nm; the thickness of the second P-SCH layer is 5±0.15nm, and the emission wavelength is 980±10nm; the thickness of the third P-SCH layer is 5±0.15nm, and the emission wavelength is 1100±10nm; the thickness of the fourth P-SCH layer is 10±0.30nm, and the emission wavelength is 1120±10nm.

[0008] The present invention also provides a CW laser epitaxial structure, characterized in that it includes the P-SCH layer described in the above technical solution.

[0009] Preferably, the substrate comprises, in sequence, an N-type InP substrate 001, an N-InP buffer layer 002, an N-InGaAsP lower confinement layer 003, an InGaAsP lower waveguide layer 004, an InGaAsP / InGaAsP quantum well active region 005, a P-SCH layer 006, a P-InGaAsP upper confinement layer 007, a P-InP buffer layer 008, a P-InGaAsP grating layer 009, a P-InP grating buried layer 010, a P-InP grating cap layer 011, a P-InP connection layer 014, a first P-InGaAsP barrier gradient layer 015-1, a second P-InGaAsP barrier gradient layer 015-2, and a P-InGaAs ohmic contact layer 016.

[0010] It also includes: a stacked P-type InP confinement layer 013 and an N-type InP confinement layer 012;

[0011] The N-type InP confinement layer 013 is located around the P-InGaAsP upper confinement layer 007, P-InP buffer layer 008, P-InGaAsP grating layer 009, P-InP grating buried layer 010 and P-InP grating cap layer 011.

[0012] The P-type InP confinement layer 012 is located around the N-InP buffer layer 002, the N-InGaAsP lower confinement layer 003, the InGaAsP lower waveguide layer 004, the InGaAsP / InGaAsP quantum well active region 005, and the InGaAsP P-SCH layer 006.

[0013] The elements of each layer in the P-SCH layer 006 are In, Ga, As, and P;

[0014] The first layer of the P-SCH layer 006 is in contact with the active region 005 of the InGaAsP / InGaAsP quantum well.

[0015] Preferably, the InGaAsP / InGaAsP quantum well active region 005 includes stacked quantum well layers and quantum barrier layers; the top and bottom layers of the InGaAsP / InGaAsP quantum well active region 005 are both quantum barrier layers.

[0016] The quantum barrier layer in contact with the first layer of the P-SCH layer 006 includes a stacked first InGaAsP layer and a second InGaAsP layer.

[0017] The thickness of the first InGaAsP layer is 10±0.30nm, and the emission wavelength is 1120±10nm; the thickness of the second InGaAsP layer is 5±0.15nm, and the emission wavelength is 1000±10nm.

[0018] The second InGaAsP layer is in contact with the first layer.

[0019] Preferably, in the InGaAsP / InGaAsP quantum well active region 005: except for the quantum barrier layer that is in contact with the first layer of the P-SCH layer 006, the thickness of the quantum barrier layer is 10±0.30nm and the emission wavelength is 1120±10nm; the thickness of the quantum well layer is 5±0.15nm and the emission wavelength is 970±10nm.

[0020] The quantum well layer has 5 layers.

[0021] Preferably, the thickness of the N-InP buffer layer 002 is 500±15nm;

[0022] The thickness of the N-InGaAsP lower confinement layer 003 is 100±3nm, the emission wavelength is 1000±10nm, and the Si doping concentration is 1×10⁻⁶. 18 cm -3 ;

[0023] The thickness of the InGaAsP lower waveguide layer 004 is 50±1.5nm, and the emission wavelength is 1057±10nm;

[0024] The thickness of the 007 confinement layer on the P-InGaAsP is 75±2.25 nm, the emission wavelength is 1000±10 nm, and the Zn doping concentration is 1×10⁻⁶. 18 cm -3 ;

[0025] The thickness of the P-InP buffer layer 008 is 80±2.4nm;

[0026] The thickness of the P-InGaAsP grating layer 009 is 30±0.9nm;

[0027] The thickness of the P-InP grating cap layer 011 is 30±0.9nm.

[0028] Preferably, the thickness of the N-InP confinement layer 013 is 800±24nm; the thickness of the P-InP confinement layer 012 is 200±6nm; and the thickness of the P-InP interconnect layer 014 is 300±9nm.

[0029] The thicknesses of the first P-InGaAsP barrier gradient layer 015-1 and the second P-InGaAsP barrier gradient layer 015-2 are independently 50±1.5nm;

[0030] In the direction from the first P-InGaAsP barrier gradient layer 015-1 to the second P-InGaAsP barrier gradient layer 015-2: the Zn doping concentration increases from 1×10⁻⁶. 18 cm -3 Increase to 5×10 19 cm -3 ;

[0031] The thickness of the P-InGaAs ohmic contact layer 016 is 200±6 nm, and the Zn doping concentration is 5×10⁻⁶. 19 cm -3 .

[0032] This invention also provides a method for fabricating the CW laser epitaxial structure described in the above technical solution, comprising the following steps:

[0033] On a substrate N-InP001, an N-InP buffer layer 002, an N-InGaAsP lower confinement layer 003, an InGaAsP lower waveguide layer 004, a quantum well active region 005, an InGaAsP P-SCH layer 006, an P-InGaAsP upper confinement layer 007, a P-InP buffer layer 008, and a P-InGaAsP grating layer precursor are sequentially deposited.

[0034] The P-InGaAsP grating layer precursor was photolithographically etched to obtain the P-InGaAsP grating layer 009.

[0035] A P-InP grating buried layer 010 and a P-InP grating cap layer 011 are deposited on the surface of the P-InGaAsP grating layer 009;

[0036] Photoresist is coated on the surfaces of substrate N-InP001, N-InP buffer layer 002, N-InGaAsP lower confinement layer 003, InGaAsP lower waveguide layer 004, quantum well active region 005, InGaAsP P-SCH layer 006, P-InGaAsP upper confinement layer 007, P-InP buffer layer 008, P-InGaAsP grating layer 009, P-InP grating buried layer 010, and P-InP grating cap layer 011. Then, a mask is deposited according to the shape formed by N-InP confinement layer 013 and P-InP confinement layer 012, followed by exposure, development, and etching to expose the areas to be deposited in N-InP confinement layer 013 and P-InP confinement layer 012.

[0037] An N-InP confinement layer 013 and a P-InP confinement layer 012 are sequentially deposited in the area to be deposited;

[0038] After removing the mask, P-InP interconnect layer 014, first P-InGaAsP barrier gradient layer 015-1, second P-InGaAsP barrier gradient layer 015-2 and P-InGaAs ohmic contact layer 016 are sequentially deposited on the surface of P-InP grating buried layer 011.

[0039] The present invention also provides a CW laser, comprising the CW laser epitaxial structure described in the above technical solution or the CW laser epitaxial structure prepared by the preparation method described in the above technical solution.

[0040] This invention solves the problem of high current density conditions (>8kA / cm) by innovatively designing the P-SCH layer. 2 The three-dimensional thermal diffusion problem of the p-type confinement layer is addressed by using a stepped thermal conductivity enhancement structure (the difference between the emission wavelength of the (n+1)th layer and the emission wavelength of the nth layer is 100–120 nm, and the difference between the emission wavelengths of the remaining adjacent layers is 10–20 nm). This provides sufficient electron barrier height in the p-region conduction band, suppresses electron leakage, facilitates hole crossing, ensures the hole injection rate, and further improves the thermal conductivity of the p-region heat conduction channel. This alleviates the heat dissipation problem caused by the high current density in the p-region, while maintaining the carrier confinement efficiency (Δn > 1 × 10⁻⁶). 18 cm -3 Without changing the thermal conductivity of the P-SCH layer, the thermal conductivity is increased to over 120 W / m·K, thereby increasing the high-temperature saturation current by more than 30%, which meets the stringent requirements of 400G / 800G optical modules for the high-temperature stability of lasers.

[0041] Furthermore, by adding materials with high thermal conductivity (the first InGaAsP layer and the second InGaAsP layer) to the outermost barrier layer of the p-region near the quantum well, heat can be carried away more directly. Combined with the design of the P-SCH layer, the influence of photon density alignment Fermi level difference caused by carrier utilization is ensured, while the influence of temperature alignment Fermi level difference is reduced, thus extending the operating state E of the laser to a certain extent. g <h v <ΔE F This delays the saturation phenomenon and increases the high-temperature saturation current.

[0042] Therefore, the stepped structure of the present invention, with a small wavelength span at both ends and a large span in the middle, largely ensures the electron leakage rate and hole injection rate, thereby controlling the rate of increase of photon density with current injection. At the same time, the addition of high thermal conductivity materials (first InGaAsP layer and second InGaAsP layer) constructs a heat conduction channel with higher thermal conductivity, which is beneficial to heat dissipation in the active region, further improving the temperature stability of the device. Attached Figure Description

[0043] Figure 1 is a schematic diagram of the epitaxial structure prepared in the example;

[0044] Figure 2 is a schematic diagram of the structure after the second extension in the embodiment;

[0045] Figure 3 is a schematic diagram of the etched structure in the embodiment;

[0046] Figure 4 is a schematic diagram of the structure after the third extension in the embodiment;

[0047] Figure 5 shows the common p_LQB and psch structures;

[0048] Figure 6 shows the electron current density curve of a conventional epitaxial structure;

[0049] Figure 7 shows the electron current density curve of the epitaxial structure prepared in the example;

[0050] Figure 8 shows the electron current density curve of a conventional epitaxial structure;

[0051] Figure 9 shows the electron current density curve of the epitaxial structure prepared in the example;

[0052] Figure 10 shows the optical power curves of the epitaxial structure (optimized structure) and the ordinary epitaxial structure (initial structure) prepared in the example at 85°C;

[0053] Figure 11 is a schematic diagram of the structure of the first InGaAsP layer, the second InGaAsP layer, and the P-SCH layer of the laser in an embodiment of the present invention. Detailed Implementation

[0054] This invention provides a P-SCH layer, which is a multi-layer structure with 2n layers, where n≥2, and the emission wavelength increases from the 1st layer to the 2nth layer.

[0055] The difference between the emission wavelength of the (n+1)th layer and the emission wavelength of the nth layer is 100-120 nm, and the difference between the emission wavelengths of the remaining adjacent layers is 10-20 nm.

[0056] In a specific embodiment of the present invention, n can be 2, 3, 4, 5, 6, 7, 8, 9 or 10; the difference between the emission wavelength of the (n+1)th layer and the emission wavelength of the nth layer can be 100nm, 105nm, 110nm, 115nm or 120nm, and the difference between the emission wavelengths of the remaining adjacent layers can be 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm or 20nm.

[0057] In this invention, when n=2, the P-SCH layer is composed of a first P-SCH layer, a second P-SCH layer, a third P-SCH layer, and a fourth P-SCH layer;

[0058] The thickness of the first P-SCH layer is preferably 5±0.15 nm, and the emission wavelength is preferably 970±10 nm; the thickness of the second P-SCH is preferably 5±0.15 nm, and the emission wavelength is preferably 980±10 nm; the thickness of the third P-SCH is preferably 5±0.15 nm, and the emission wavelength is preferably 1100±10 nm; the thickness of the fourth P-SCH is preferably 10±0.30 nm, and the emission wavelength is preferably 1120±10 nm.

[0059] The present invention also provides a CW laser epitaxial structure, including the InGaAsPP-SCH layer described in the above technical solution.

[0060] The CW laser epitaxial structure provided by the present invention preferably includes an N-type InP substrate 001 to improve the flatness of the substrate surface;

[0061] The CW laser epitaxial structure provided by the present invention preferably includes an N-InP buffer layer 002 on the surface of an N-type InP substrate 001; the thickness of the N-InP buffer layer 002 is preferably 500±15nm;

[0062] The CW laser epitaxial structure provided by this invention preferably includes an N-InGaAsP lower confinement layer 003 on the surface of an N-InP buffer layer 002; the thickness of the N-InGaAsP lower confinement layer 003 is preferably 100±3 nm, the emission wavelength is preferably 1000±10 nm, and the Si doping concentration is preferably 1×10⁻⁶. 18 cm -3 ;

[0063] The CW laser epitaxial structure provided by the present invention preferably includes an InGaAsP lower waveguide layer 004 on the surface of the N-InGaAsP lower confinement layer 003; the thickness of the InGaAsP lower waveguide layer 004 is preferably 50±1.5nm, and the emission wavelength is preferably 1057±10nm.

[0064] The CW laser epitaxial structure provided by the present invention preferably includes an InGaAsP / InGaAsP quantum well active region 005 on the surface of the InGaAsP lower waveguide layer 004; the InGaAsP / InGaAsP quantum well active region 005 preferably includes a stacked quantum well layer and a quantum barrier layer; the top and bottom layers of the InGaAsP / InGaAsP quantum well active region 005 are preferably both quantum barrier layers; the quantum barrier layer in contact with the first layer of the P-SCH layer 006 preferably includes a stacked first InGaAsP layer and a second InGaAsP layer; the thickness of the first InGaAsP layer is preferably 10±0.30nm, and the emission wavelength is preferably 1120±10nm; the thickness of the second InGaAsP layer is preferably 5±0.15nm, and the emission wavelength is preferably 1000±10nm; the second InGaAsP layer is in contact with the first layer.

[0065] In this invention, in the InGaAsP / InGaAsP quantum well active region 005: the thickness of the quantum barrier layer, excluding the quantum barrier layer that contacts the first layer of the P-SCH layer 006, is preferably 10±0.30 nm, and the emission wavelength is preferably 1120±10 nm; the thickness of the quantum well layer is preferably 5±0.15 nm, and the emission wavelength is preferably 970±10 nm; the number of quantum well layers is preferably 5.

[0066] The CW laser epitaxial structure provided by the present invention preferably includes a P-SCH layer 006 on the surface of the InGaAsP / InGaAsP quantum well active region 005; the elements of each layer in the P-SCH layer 006 are In, Ga, As and P; the first layer of the P-SCH layer 006 is in contact with the InGaAsP / InGaAsP quantum well active region 005.

[0067] The CW laser epitaxial structure provided by this invention preferably includes a P-InGaAsP confinement layer 007 on the surface of an N-type P-SCH layer 006; the thickness of the P-InGaAsP confinement layer 007 is preferably 75±2.25 nm, the emission wavelength is preferably 1000±10 nm, and the Zn doping concentration is preferably 1×10⁻⁶. 18 cm -3 ;

[0068] The CW laser epitaxial structure provided by the present invention preferably includes a P-InP buffer layer 008 on the surface of the P-InGaAsP confinement layer 007; the thickness of the P-InP buffer layer 008 is preferably 80±2.4nm;

[0069] The CW laser epitaxial structure provided by the present invention preferably includes a P-InGaAsP grating layer 009 on the surface of a P-InP buffer layer 008; the thickness of the P-InGaAsP grating layer 009 is preferably 30±0.9nm, the emission wavelength is preferably 1150±10nm, the depth is 30±1nm, and the period is preferably 202nm.

[0070] The CW laser epitaxial structure provided by the present invention preferably includes a P-InP grating buried layer 010 on the surface of the P-InGaAsP grating layer 009; the thickness of the P-InP grating buried layer 010 is preferably 10 nm, and the emission wavelength is preferably 917 nm.

[0071] The CW laser epitaxial structure provided by the present invention preferably includes a P-InP grating cap layer 011 on the surface of the P-InP grating buried layer 010; the thickness of the P-InP grating cap layer 011 is preferably 30±0.9nm.

[0072] The CW laser epitaxial structure provided by the present invention preferably includes a P-InP bonding layer 014 on the surface of the P-InP grating cap layer 011; the thickness of the P-InP bonding layer 014 is preferably 300±9nm.

[0073] The CW laser epitaxial structure provided by the present invention preferably includes a first P-InGaAsP barrier gradient layer 015-1 on the surface of the P-InP interconnect layer 014; the thickness of the first P-InGaAsP barrier gradient layer 015-1 is preferably 50±1.5nm independently.

[0074] The CW laser epitaxial structure provided by this invention preferably includes a second P-InGaAsP barrier gradient layer 015-2 on the surface of a first P-InGaAsP barrier gradient layer 015-1; the thickness of the first P-InGaAsP barrier gradient layer 015-1 is preferably 50 nm; in the direction from the first P-InGaAsP barrier gradient layer 015-1 to the second P-InGaAsP barrier gradient layer 015-2: the Zn doping concentration is preferably from 1 × 10⁻⁶. 18 cm -3 Increase to 5×10 19 cm -3 ;

[0075] The CW laser epitaxial structure provided by this invention preferably includes a P-InGaAs ohmic contact layer 016 on the surface of the second P-InGaAs P barrier gradient layer 015-2; the thickness of the P-InGaAs ohmic contact layer 016 is preferably 200±6nm, and the Zn doping concentration is preferably 5×10⁻⁶nm. 19 cm -3 .

[0076] The CW laser epitaxial structure provided by the present invention preferably includes a stacked N-type InP confinement layer 013 and a P-type InP confinement layer 012;

[0077] The N-type InP confinement layer 013 is located around the P-InGaAsP upper confinement layer 007, P-InP buffer layer 008, P-InGaAsP grating layer 009 and P-InP grating buried layer 010.

[0078] The P-type InP confinement layer 012 is located around the N-InP buffer layer 002, the N-InGaAsP lower confinement layer 003, the InGaAsP lower waveguide layer 004, the InGaAsP / InGaAsP quantum well active region 005, and the InGaAsP P-SCH layer 006; the N-type InP confinement layer 013 and the P-type InP confinement layer 012 form a PNPN thyristor structure.

[0079] The thickness of the N-InP confinement layer 013 is 800±24nm; the thickness of the P-InP confinement layer 012 is 200±6nm.

[0080] This invention also provides a method for fabricating the CW laser epitaxial structure described in the above technical solution, comprising the following steps:

[0081] On a substrate N-InP001, an N-InP buffer layer 002, an N-InGaAsP lower confinement layer 003, an InGaAsP lower waveguide layer 004, a quantum well active region 005, an InGaAsP P-SCH layer 006, an P-InGaAsP upper confinement layer 007, a P-InP buffer layer 008, and a P-InGaAsP grating layer precursor are sequentially deposited.

[0082] The P-InGaAsP grating layer precursor was photolithographically etched to obtain the P-InGaAsP grating layer 009.

[0083] A P-InP grating buried layer 010 and a P-InP grating cap layer 011 are deposited on the surface of the P-InGaAsP grating layer 009;

[0084] Photoresist is coated on the surfaces of substrate N-InP001, N-InP buffer layer 002, N-InGaAsP lower confinement layer 003, InGaAsP lower waveguide layer 004, quantum well active region 005, InGaAsP P-SCH layer 006, P-InGaAsP upper confinement layer 007, P-InP buffer layer 008, P-InGaAsP grating layer 009, P-InP grating buried layer 010, and P-InP grating cap layer 011. Then, a mask is deposited according to the shape formed by N-InP confinement layer 013 and P-InP confinement layer 012, followed by exposure, development, and etching to expose the areas to be deposited in N-InP confinement layer 013 and P-InP confinement layer 012.

[0085] An N-InP confinement layer 013 and a P-InP confinement layer 012 are sequentially deposited in the area to be deposited;

[0086] After removing the mask, P-InP interconnect layer 014, first P-InGaAsP barrier gradient layer 015-1, second P-InGaAsP barrier gradient layer 015-2 and P-InGaAs ohmic contact layer 016 are sequentially deposited on the surface of P-InP grating buried layer 011.

[0087] The present invention also provides a CW laser, comprising the CW laser epitaxial structure described in the above technical solution or the CW laser epitaxial structure prepared by the preparation method described in the above technical solution.

[0088] The following detailed description of the P-SCH layer, CW laser epitaxial structure, and fabrication method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0089] Figure 1 is a schematic diagram of the epitaxial structure prepared in the example.

[0090] Example 1

[0091] The manufacturing process employs a four-stage epitaxial growth process combined with photolithography and etching techniques.

[0092] First extension (basic structure growth)

[0093] Process conditions: MOCVD equipment, N-InP001 substrate;

[0094] Growth sequence:

[0095] N-InP buffer layer 002: 500nm thick, used to improve substrate surface flatness;

[0096] N-InGaAsP lower confinement layer 003: thickness 100nm, emission wavelength 1000nm, Si doping concentration 1×10⁻⁶ 18 cm-3 ;

[0097] InGaAsP waveguide layer 004: 50nm thickness, 1057nm emission wavelength;

[0098] The active region of the quantum well 005 is an InGaAsP / InGaAsP multi-quantum-well structure. There are 5 sets of quantum wells near the N side (a total of 6 quantum barrier layers and 5 quantum well layers). Each barrier layer is 10 nm thick and the well layer is 5 nm thick. The outermost quantum barrier near the p side is 15 nm thick and is divided into two InGaAsP layers: one with a thickness of 10 nm and an emission wavelength of 1120 nm, and the other with a thickness of 5 nm and an emission wavelength of 1000 nm. The emission wavelength of the remaining quantum barrier layers is 1120 nm, and the emission wavelength of the quantum well layers is 1340 nm.

[0099] InGaAsPP-SCH layer 006: 5nm thick InGaAsP with 970nm emission wavelength, 5nm thick InGaAsP with 980nm emission wavelength, 5nm thick InGaAsP with 1100nm emission wavelength, and 10nm thick InGaAsP with 1120nm emission wavelength.

[0100] P-InGaAsP confinement layer 007: 75 nm thick, emission wavelength 1000 nm, Zn doping concentration 1 × 10⁻⁶ 18 cm -3 ;

[0101] P-InP buffer layer 008: 80nm thickness, emission wavelength 917nm;

[0102] P-InGaAsP grating layer 009: 30nm thick, emission wavelength 1150nm, depth 30nm, photolithography process: grating pattern with a period of 202nm is fabricated on the surface of grating layer 009 by holographic exposure.

[0103] Used to form a distributed feedback DFB grating.

[0104] Figure 11 is a schematic diagram of the structure of the first InGaAsP layer P-LQB1, the second InGaAsP layer P-LQB2, and the P-SCH layers (psch1~4) of the laser in an embodiment of the present invention.

[0105] Second extension

[0106] Epitaxial growth:

[0107] P-InP grating buried layer 010: 10nm thick, emission wavelength 917nm;

[0108] P-InP grating cap layer 011: 30nm thick, emission wavelength 917nm;

[0109] Figure 2 is a schematic diagram of the structure after the second extension in the embodiment.

[0110] Third epitaxy (lateral confinement layer growth)

[0111] Mask fabrication: Photoresist is coated on the surfaces of substrate N-InP001, N-InP buffer layer 002, N-InGaAsP lower confinement layer 003, InGaAsP lower waveguide layer 004, quantum well active region 005, InGaAsP-SCH layer 006, P-InGaAsP upper confinement layer 007, P-InP buffer layer 008, P-InGaAsP grating layer 009, P-InP grating buried layer 010, and P-InP grating cap layer 011. Then, SiO2 thin film is deposited according to the shape formed by N-InP confinement layer 013 and P-InP confinement layer 012. The areas to be deposited in N-InP confinement layer 013 and P-InP confinement layer 012 are not deposited. Low-temperature and low-speed deposition is carried out using PEALD equipment with a temperature ≤150℃ and a thickness of 500nm to reduce film stress.

[0112] Exposure, development and etching: Form a mesa structure with a width ranging from 1.5 to 1.7 μm to expose the periphery of the quantum well active region 005.

[0113] Figure 3 is a schematic diagram of the etched structure in the embodiment.

[0114] Epitaxial growth:

[0115] A small amount of P-type doped source diethylzinc is introduced to grow the first P-InP confinement layer 012, with a thickness of 800 nm and an emission wavelength of 917 nm; then the N-type doped source SiH4 is switched to grow the second N-InP confinement layer 013, with a thickness of 200 nm and an emission wavelength of 917 nm.

[0116] Figure 4 is a schematic diagram of the structure after the third extension in the embodiment.

[0117] Fourth epitaxial surface functional layer integration

[0118] Dielectric film removal: The SiO2 mask layer was removed using HF;

[0119] Epitaxial growth:

[0120] P-InP interconnect layer 014: 300nm thick, connecting the lateral confinement layer and the top electrode;

[0121] P-InGaAsP barrier gradient layers 015-1 and 015-2: two 50nm layers each, with Zn gradient doping concentrations starting from 1×10⁻⁶.18 cm -3 Up to 5×10 19 cm -3 ;

[0122] P-InGaAs ohmic contact layer 016: 200 nm thick, Zn doping concentration 5 × 10⁻⁶ 19 cm -3 This reduces contact resistance.

[0123] Final structure: After four epitaxys, a complete epitaxial structure as shown in Figure 1 is formed, achieving synergistic optimization of high thermal conductivity channels and carrier confinement.

[0124] The epitaxial structure (optimized structure) with the above-mentioned heat-conducting channels p_LQB and psch structures was simulated using simulation software. The simulation results were compared with those of the ordinary epitaxial structure with ordinary p_LQB and psch structures (initial structure, the ordinary epitaxial structure differs from the epitaxial structure of this embodiment only in the p_LQB and psch structures: p_LQB has a thickness of 15nm, an emission wavelength of 1120nm, and is InGaAsP; psch structure has a thickness of 25nm, an emission wavelength of 1120nm, and is InGaAsP).

[0125] Figure 5 shows the common p_LQB and psch structures;

[0126] Figure 6 shows the electron current density curve of a conventional epitaxial structure;

[0127] Figure 7 shows the electron current density curve of the epitaxial structure prepared in the example;

[0128] Figure 8 shows the electron current density curve of a conventional epitaxial structure;

[0129] Figure 9 shows the electron current density curve of the epitaxial structure prepared in the example;

[0130] Figure 10 shows the optical power curves of the epitaxial structure (optimized structure) and the ordinary epitaxial structure (initial structure) prepared in the example at 85°C.

[0131] As shown in Figures 6-9, under the same current injection, the electron leakage rate of the initial structure is 21.08%, and the electron leakage rate of the optimized structure is 18.63%. The hole injection rates of the two structures are similar, so the carrier utilization rate of the active region is not much different.

[0132] As shown in Figure 10, the high-temperature saturation current of the optimized structure is more than 10mA greater than that of the initial structure, while the maximum power is more than 10mW greater than that of the initial structure.

[0133] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A P-SCH layer, characterized in that, It has a multi-layer structure with 2n layers, where n≥2. The emission wavelength increases from the 1st layer to the 2nth layer. The difference between the emission wavelength of the (n+1)th layer and the emission wavelength of the nth layer is 100~120nm, and the difference between the emission wavelengths of the remaining adjacent layers is 10~20nm.

2. The P-SCH layer according to claim 1, characterized in that, When n=2, the P-SCH layer consists of a first P-SCH layer, a second P-SCH layer, a third P-SCH layer, and a fourth P-SCH layer; the first P-SCH layer has a thickness of 5±0.15nm and an emission wavelength of 970±10nm; the second P-SCH layer has a thickness of 5±0.15nm and an emission wavelength of 980±10nm; the third P-SCH layer has a thickness of 5±0.15nm and an emission wavelength of 1100±10nm; and the fourth P-SCH layer has a thickness of 10±0.30nm and an emission wavelength of 1120±10nm.

3. A CW laser epitaxial structure, characterized in that, Includes the P-SCH layer as described in claim 1 or 2.

4. The CW laser epitaxial structure according to claim 3, characterized in that, The structure includes, in sequence, an N-type InP substrate (001), an N-InP buffer layer (002), an N-InGaAsP lower confinement layer (003), an InGaAsP lower waveguide layer (004), an InGaAsP / InGaAsP quantum well active region (005), a P-SCH layer (006), a P-InGaAsP upper confinement layer (007), a P-InP buffer layer (008), a P-InGaAsP grating layer (009), a P-InP grating buried layer (010), a P-InP grating cap layer (011), a P-InP interconnect layer (014), a first P-InGaAsP barrier gradient layer (015-1), a second P-InGaAsP barrier gradient layer (015-2), and a P-InGaAs ohmic contact layer (016); it also includes, in sequence, a stacked P-InP confinement layer (013) and an N-InP... The confinement layer (012) is located outside the P-InGaAsP upper confinement layer (007), P-InP buffer layer (008), P-InGaAsP grating layer (009), P-InP grating buried layer (010) and P-InP grating cap layer (011). The P-InP confinement layer (012) is located outside the N-InP buffer layer (002), N-InGaAsP lower confinement layer (003), InGaAsP lower waveguide layer (004), InGaAsP / InGaAsP quantum well active region (005), and InGaAsP P-SCH layer (006). The elements of each layer in the P-SCH layer (006) are In, Ga, As and P. The first layer of the P-SCH layer (006) is adjacent to the InGaAsP / InGaAsP quantum well active region. The active region of the quantum well (005) is in phase contact.

5. The CW laser epitaxial structure according to claim 4, characterized in that, The InGaAsP / InGaAsP quantum well active region (005) includes stacked quantum well layers and quantum barrier layers; the top and bottom layers of the InGaAsP / InGaAsP quantum well active region (005) are both quantum barrier layers; the quantum barrier layer in contact with the first layer of the P-SCH layer (006) includes stacked first InGaAsP layer and second InGaAsP layer; the thickness of the first InGaAsP layer is 10±0.30nm and the emission wavelength is 1120±10nm; the thickness of the second InGaAsP layer is 5±0.15nm and the emission wavelength is 1000±10nm; the second InGaAsP layer is in contact with the first layer.

6. The CW laser epitaxial structure according to claim 5, characterized in that, In the InGaAsP / InGaAsP quantum well active region (005): except for the quantum barrier layer that is in contact with the first layer of the P-SCH layer (006), the thickness of the quantum barrier layer is 10±0.30nm and the emission wavelength is 1120±10nm; the thickness of the quantum well layer is 5±0.15nm and the emission wavelength is 970±10nm; the number of quantum well layers is 5.

7. The CW laser epitaxial structure according to claim 4, characterized in that, The thickness of the N-InP buffer layer (002) is 500±15nm; the thickness of the N-InGaAsP lower confinement layer (003) is 100±3nm, the emission wavelength is 1000±10nm, and the Si doping concentration is 1×10⁻⁶. 18 cm -3 The InGaAsP lower waveguide layer (004) has a thickness of 50±1.5 nm and an emission wavelength of 1057±10 nm; the P-InGaAsP upper confinement layer (007) has a thickness of 75±2.25 nm, an emission wavelength of 1000±10 nm, and a Zn doping concentration of 1×10⁻⁶. 18 cm -3 The thickness of the P-InP buffer layer (008) is 80±2.4nm; the thickness of the P-InGaAsP grating layer (009) is 30±0.9nm; and the thickness of the P-InP grating cap layer (011) is 30±0.9nm.

8. The CW laser epitaxial structure according to claim 4, characterized in that, The thickness of the N-InP confinement layer (013) is 800±24 nm; the thickness of the P-InP confinement layer (012) is 200±6 nm; the thickness of the P-InP interconnect layer (014) is 300±9 nm; the thicknesses of the first P-InGaAsP barrier gradient layer (015-1) and the second P-InGaAsP barrier gradient layer (015-2) are independently 50±1.5 nm; in the direction from the first P-InGaAsP barrier gradient layer (015-1) to the second P-InGaAsP barrier gradient layer (015-2): the Zn doping concentration increases from 1×10⁻⁶. 18 cm -3 Increase to 5×10 19 cm -3 The thickness of the P-InGaAs ohmic contact layer (016) is 200±6 nm, and the Zn doping concentration is 5×10⁻⁶. 19 cm -3 .

9. The method for fabricating the CW laser epitaxial structure according to any one of claims 4 to 8, characterized in that, Includes the following steps: On an N-InP substrate (001), an N-InP buffer layer (002), an N-InGaAsP lower confinement layer (003), an InGaAsP lower waveguide layer (004), a quantum well active region (005), an InGaAsP P-SCH layer (006), an InGaAsP upper confinement layer (007), a P-InP buffer layer (008), and a P-InGaAsP grating layer precursor are sequentially deposited. The P-InGaAsP grating layer precursor is photolithographically ... Photoresist is coated on the surfaces of the lower waveguide layer (004), the quantum well active region (005), the InGaAsP-SCH layer (006), the P-InGaAsP upper confinement layer (007), the P-InP buffer layer (008), the P-InGaAsP grating layer (009), the P-InP grating buried layer (010), and the P-InP grating cap layer (011). Then, a mask is deposited according to the shape formed by the N-InP confinement layer (013) and the P-InP confinement layer (012), followed by exposure, development, and etching to expose the areas to be deposited for the N-InP confinement layer (013) and the P-InP confinement layer (012). The N-InP confinement layer (013) and the P-InP confinement layer (012) are then deposited sequentially in these areas. After removing the mask, P-InP is deposited sequentially on the surface of the P-InP grating buried layer (011). The layer consists of a connecting layer (014), a first P-InGaAsP barrier gradient layer (015-1), a second P-InGaAsP barrier gradient layer (015-2), and a P-InGaAs ohmic contact layer (016).

10. A CW laser, characterized in that, Includes the CW laser epitaxial structure according to any one of claims 3 to 8 or the CW laser epitaxial structure prepared by the preparation method according to claim 9.

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