An improved spectral infrared led epitaxial wafer and method of making the same

Abstract

The present application relates to the technical field of LED, in particular to an infrared LED epitaxial wafer for improving spectrum and a preparation method thereof.The infrared LED epitaxial wafer comprises, from bottom to top, an N-type GaAs substrate, an N-type GaAs buffer layer, an N-type current expansion layer, an N-type confinement layer, a voltage division type single-peak light emitting layer, a P-type confinement layer, a P-type current expansion layer and a P-face contact layer.The voltage division type single-peak light emitting layer is a periodic structure grown by a fluctuation layer, a quantum well layer, a strain transition layer and a quantum barrier layer in sequence.Based on a conventional 940nm infrared LED epitaxial structure, the voltage division type single-peak light emitting layer is designed, which can effectively solve the double-peak problem caused by the light emitting spectrum anomaly due to the In component segregation local state, stress sudden change energy level splitting and unstable TMIn source of the precursor supply and other factors.The infrared LED has stable spectrum and only a single light emitting peak, and has excellent performance.

Description

Technical Field

[0001] This invention relates to the field of LED technology, specifically to an infrared LED epitaxial wafer with improved spectrum and its preparation method. Background Technology

[0002] Infrared LEDs (light-emitting diodes) are semiconductor light sources that emit light in the range of 780nm to 1600nm. Their core technology is based on the electroluminescence effect of III-V group compounds (such as GaAs, AlGaAs, and InGaAs). Unlike visible light LEDs, the light radiation from infrared LEDs cannot be directly observed by the human eye and must be captured by an infrared sensor. Infrared LEDs with an emission wavelength of 940nm are the most widely used infrared products, extensively applied in mobile phone cameras, security monitoring, infrared detection, infrared remote sensing, and high-speed communications.

[0003] As applications deepen, the double-peak problem in the emission spectrum of 940nm infrared LEDs has been a persistent challenge for engineers. Conventional 940nm infrared LED epitaxial structures include... Figure 1 As shown, the epitaxial layers are grown starting from the N-type GaAs substrate 100, and from bottom to top are the N-type GaAs buffer layer 101, the N-type current spreading layer 102, the N-type confinement layer 103, the multi-quantum-well light-emitting layer 104, the P-type confinement layer 105, the P-type current spreading layer 106, and the P-face contact layer 107. During the epitaxial growth process, the thickness of the quantum well structure is uneven due to material stress, or there are regions of different thicknesses in the active region, resulting in differences in the emission wavelength in different regions, thus producing a double peak. In addition, the epitaxial structure is grown using MOCVD (metal-organic chemical vapor deposition). Since the group III source TMI is a solid source material, if there is slight blockage in the TMI pipeline during the growth of the quantum well InGaAs material, it will cause fluctuations in the In composition, resulting in uneven distribution of the In composition within the quantum well and producing a double peak in the emission wavelength. Meanwhile, at a wavelength of 940 nm, quantum well InGaAs materials exhibit significant compressive stress due to the large lattice difference between the material and the substrate, which easily leads to band splitting and the generation of bimodal spectra. This bimodal problem can severely impact the normal operation of applications requiring high monochromaticity, such as optocouplers, biosensors, or communication applications. Therefore, developing an LED that can improve the spectral bimodal problem of 940 nm infrared LEDs is particularly important. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present application provides an infrared LED epitaxial wafer with improved spectrum and a preparation method thereof, the infrared LED epitaxial wafer has stable spectrum and only a single light emitting peak, effectively solving the double-peak problem of the light emitting spectrum of the conventional infrared LED quantum well caused by the In component segregation local state, stress mutation energy level splitting and instability of the TMIn source of the precursor supply and other factors.

[0005] The first object of the present application is to provide an infrared LED epitaxial wafer with improved spectrum, which is grown from an N-type GaAs substrate to grow epitaxial layers from bottom to top, including an N-type GaAs buffer layer, an N-type current expansion layer, an N-type confinement layer, a single-peak light emitting layer with pressure division, a P-type confinement layer, a P-type current expansion layer and a P-face contact layer.

[0006] The single-peak light emitting layer with pressure division is a periodic structure grown from a fluctuation layer, a quantum well layer, a strain transition layer and a quantum barrier layer.

[0007] The present application is based on the conventional 940nm infrared LED epitaxial structure, and before growing each quantum well material InGaAs, a fluctuation layer is grown, and by changing the growth process, the local state caused by the uneven In component of In in the conventional InGaAs material can be inhibited, which is beneficial to repair the low In area and ensure the uniformity of the In component in each atomic layer of the well layer; and after the growth of each quantum well InGaAs is completed, a strain transition layer is grown before growing the quantum barrier layer, and by controlling the In component, the strain from the compressive stress mutation to the tensile strain in the conventional 940nm infrared LED is improved, and the spectrum double-peak problem caused by the energy band splitting caused by the strain mutation is avoided.

[0008] Further, the cycle number of the periodic structure is 6 pairs to 12 pairs.

[0009] Further, the material of the fluctuation layer is InAs, and the thickness in each cycle is 5nm to 10nm; the fluctuation layer is undoped.

[0010] Further, the material of the strain transition layer is In x1 Ga 1-x1AsP, the thickness in each cycle is 20nm-30nm, wherein the initial In component x1 is set to 0.15, x1 gradually decreases from 0.15 to 0 during the growth of the strain transition layer, and the gradient rate of x1 is 0.01 / s. The design principle of the strain transition layer behind the well is to utilize the tensile strain characteristics between the InGaAsP material and the GaAs substrate lattice, adopt the mode of gradually reducing the In component and continuously increasing PH3 during growth, on the one hand, the lattice size can be reduced by reducing the In component to reduce the compressive strain, on the other hand, the strain form is slowly transitioned from compressive strain to tensile strain through the compensation of P element, instead of stress mutation, so that the problem of spectral double peaks caused by energy band splitting due to strain mutation can be effectively avoided.

[0011] The second object of the application is to provide a preparation method of an infrared LED epitaxial wafer with improved spectrum, which comprises growing, on an N-type GaAs substrate by using a MOCVD device, an N-type GaAs buffer layer, an N-type current expansion layer, an N-type confinement layer, a split-pressure single-peak light emitting layer, a P-type confinement layer, a P-type current expansion layer and a P-face contact layer in sequence; the split-pressure single-peak light emitting layer is a periodic structure grown in sequence by a fluctuation layer, a quantum well layer, a strain transition layer and a quantum barrier layer; the fluctuation layer, the quantum well layer and the strain transition layer are all grown by using a split-pressure two-way TMIn source series connection process.

[0012] Further, the split-pressure two-way TMIn source series connection process is as follows: two bottles of TMIn source are connected in series, one bottle of TMIn source close to the reaction chamber is set to have a bottle pressure of 200mbar-300mbar during growth, and the other bottle of TMIn source away from the reaction chamber is set to have a pressure of 800mbar-1000mbar during growth.

[0013] In the epitaxial wafer preparation process, the single bottle TMIn source used in the conventional growth process is improved to a double-way TMIn source series connection mode for growth. By using the double-way TMIn source series connection growth mode and keeping the pressure difference between the inlet and outlet, it can be ensured that the TMIn source entering the reaction chamber is always from a low pressure state, and the front end has a high bottle pressure source as a precursor supplement, so that the problem of unstable concentration of TMIn as a solid organic metal source entering the reaction chamber can be improved, thereby preventing the fluctuation of In component in the quantum well and improving the double peak. In addition, the split-pressure series connection technology can also prevent the blockage of the pipeline during the use of the TMIn source, and can also avoid the problem of In component fluctuation and double peak caused by the increase of the outflow setting flow of the TMIn source at the bottle bottom.

[0014] Further, the growth step of the fluctuation layer is as follows: the reaction chamber temperature is set to 690℃±10℃, TMIn and AsH3 are input, and InAs material with a thickness of 5nm-10nm is grown.

[0015] Further, after the growth of the fluctuation layer, the fluctuation layer is annealed at 700-720 DEG C, and TMGa and AsH3 are introduced during the annealing process, wherein the flow rate of TMGa is set to 40-60 sccm, and the flow rate of AsH3 is set to 400-600 sccm. In this technical solution, after the growth of the fluctuation layer, the fluctuation layer is annealed at 700-720 DEG C and TMGa and AsH3 are introduced, and the In broken bonds generated by the cleavage effect of InAs at high temperature can react with Ga and As atoms on the surface of the epitaxial layer to form an InGaAs nucleation buffer layer, so that the problem of bimodal distribution caused by the inconsistent In component due to the random aggregation of In atoms to form high-In and low-In regions during the conventional growth of an InGaAs quantum well structure can be prevented.

[0016] Further, the growth of the strain transition layer comprises the following steps: setting the temperature of the reaction chamber to 690 DEG C + / - 10 DEG C, introducing TMIn, TMGa, AsH3 and PH3, and growing an InGaAs material with a thickness of 20-30 nm. x1 Ga 1-x1 AsP material, wherein the initial In component x1 is set to 0.15, and x1 gradually decreases from 0.15 to 0 during the growth of the strain transition layer, and the rate of the gradual change of x1 is 0.01 / s.

[0017] Further, the initial flow rate of PH3 is set to 300 sccm during the growth of the strain transition layer, and then the flow rate of PH3 gradually increases from 300 sccm to 600 sccm during the growth of the strain transition layer, wherein the rate of the gradual change is 5 sccm / s.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The application is based on the conventional 940nm infrared LED epitaxial structure, adopts the design of the single-peak light emitting layer with pressure division, on the one hand, the single-peak light emitting layer with pressure division is designed as a periodic structure grown in sequence by the fluctuation layer, the quantum well layer, the strain transition layer and the quantum barrier layer, the fluctuation layer is used to inhibit the local state caused by the uneven In component in the conventional InGaAs material due to the segregation of In, the problem of the double peaks caused by the inconsistent In component in the quantum well is solved, the strain transition layer is used to improve the defect that the strain between the well / barrier in the conventional 940nm infrared LED changes from the compressive stress to the tensile stress, the problem of the spectral double peaks caused by the energy band splitting caused by the strain mutation is avoided, on the other hand, the fluctuation layer, the quantum well layer and the strain transition layer in the single-peak light emitting layer with pressure division are grown by the pressure division double-path TMIn source series process, the problem of the unstable concentration of TMIn as a solid-state organic metal source into the reaction chamber is improved, the problem of the double peaks caused by the fluctuation of the In component in the quantum well is prevented, at the same time, the problem of the double peaks caused by the fluctuation of the In component due to the blockage of TMIn source in the pipeline or the increase of the source flow setting in the TMIn source used to the bottle bottom is prevented.

[0020] The infrared LED prepared by the application has stable spectrum and only single light emitting peak, excellent performance, and can be applied to the photoelectric coupler, the biological sensor or the communication application field. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the conventional 940nm infrared LED epitaxial wafer;

[0022] Figure 2 It is a structural schematic diagram of the infrared LED epitaxial wafer of the application;

[0023] Figure 3 It is a schematic diagram of one cycle structure of the single-peak light emitting layer with pressure division of the application;

[0024] Figure 4 It is a test spectrum diagram of the infrared LED of the application;

[0025] Figure 5 It is a test spectrum diagram of the conventional 940nm infrared LED.

[0026] Explanation of reference numerals in the schematic diagram:

[0027] 100, N-type GaAs substrate; 101, N-type GaAs buffer layer; 102, N-type current expansion layer; 103, N-type confinement layer; 104, multi-quantum well light emitting layer; 105, P-type confinement layer; 106, P-type current expansion layer; 107, P-face contact layer; 204, single-peak light emitting layer with pressure division; 205, fluctuation layer; 206, quantum well layer; 207, strain transition layer; 208, quantum barrier layer. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and not intended to be limiting on the present application and its applications or uses. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present application.

[0029] In the description of the present application, it should be understood that the use of the words "first", "second" and the like words to define elements is merely intended to facilitate the distinction between the corresponding elements, and the above words do not have special meanings unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.

[0030] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are usually based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and in the absence of the opposite description, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0031] Please refer to Figures 1 to 5 It should be noted that the diagrams provided in the embodiments only illustrate the basic concept of the present application in a schematic manner, and only show the components related to the present application in the diagrams, not the number, shape and size of the components when actually implemented. The shape, number and proportion of each component when actually implemented can be arbitrarily changed, and the component layout form can also be more complex.

[0032] An embodiment of the present application provides an infrared LED epitaxial wafer for improving spectrum, a structural schematic diagram of which is shown in Figure 2 The epitaxial layer is grown from the N-type GaAs substrate 100, and the N-type GaAs buffer layer 101, the N-type current expansion layer 102, the N-type confinement layer 103, the voltage division type single-peak light emitting layer 204, the P-type confinement layer 105, the P-type current expansion layer 106, and the P-face contact layer 107 are sequentially grown from bottom to top.

[0033] Specifically, the voltage division type single-peak light emitting layer is a periodic structure sequentially grown by the fluctuation layer 205, the quantum well layer 206, the strain transition layer 207, and the quantum barrier layer 208, and the cycle logarithm is 6 pairs to 12 pairs, and a schematic diagram of a single cycle structure is shown in Figure 3 .

[0034] In some embodiments, the fluctuation layer is made of InAs, and has a thickness of 5-10 nm in each cycle; and the fluctuation layer is undoped.

[0035] In some embodiments, the strain transition layer is made of In x1 Ga 1-x1 AsP, and has a thickness of 20-30 nm in each cycle, wherein the initial In component x1 is set to 0.15, x1 gradually decreases from 0.15 to 0 during the growth of the strain transition layer, and the rate of the gradual change of x1 is 0.01 / s.

[0036] In some embodiments, the fluctuation layer, the quantum well layer, and the strain transition layer are grown by using a two-way TMIn source series process. The two-way TMIn source series process refers to connecting two TMIn source bottles in series, and setting the pressure of the TMIn source bottle close to the reaction chamber to 200-300 mbar during growth, and setting the pressure of the TMIn source bottle far from the reaction chamber to 800-1000 mbar during growth. By optimizing the light-emitting quantum well layer of a conventional 940 nm infrared LED to a single-peak light-emitting region grown by using the two-way TMIn source series process, the fluctuation layer is used to solve the problem of the formation of localized states caused by the segregation of In in InGaAs quantum well material, and the strain transition layer is used to improve the defect that the stress suddenly changes from compressive stress to tensile stress between the well and the barrier, so as to finally solve the problem of the existence of double peaks in the spectrum of the conventional 940 nm infrared LED.

[0037] In another embodiment, the present application further provides a preparation method of an infrared LED epitaxial wafer with improved spectrum. The method comprises the following steps:

[0038] (1) The MOCVD is extracted to a low pressure of 50 mbar in a pure H2 atmosphere, the reaction chamber is set to a temperature of 400°C, then the N-type GaAs substrate is transferred to the reaction chamber through a mechanical hand transfer bin, and then rapidly heated to 700°C and maintained at 700°C for 5 min.

[0039] (2) Growth of N-type GaAs buffer layer: the reaction chamber is set to a temperature of 690℃±10℃, TMGa and AsH3 are introduced, and a GaAs buffer layer material with a thickness of 200nm-300nm is grown, SiH4 is used as an N-type dopant, and the doping concentration is 1×10 18 cm -3 ~2×10 18 cm -3 .

[0040] (3) Growth of N-type current expansion layer: the reaction chamber is set to a temperature of 690℃±10℃, TMGa, TMAl and AsH3 are introduced, and an Al y1 Ga 1-y1 As material with a thickness of 2000nm-3000nm is grown, the value of y1 is in the range of 0.1-0.15, SiH4 is used as an N-type dopant, and the doping concentration is 0.7×10 18 cm -3 ~1.5×10 18 cm -3 .

[0041] (4) Growth of N-type confinement layer: the reaction chamber is set to a temperature of 720℃±10℃, TMGa, TMAl and AsH3 are introduced, and an Al y2 Ga 1-y2 As material with a thickness of 400nm-500nm is grown, the value of y2 is in the range of 0.25-0.50, SiH4 is used as an N-type dopant, and the doping concentration is 1×10 18 cm -3 ~2×10 18 cm -3 .

[0042] (5) Growth of pressure ratio single-peak luminescence layer: the luminescence layer is a periodic structure of fluctuation layer, quantum well layer, strain transition layer and quantum barrier layer grown in sequence, and the cycle logarithm is 6 pairs-12 pairs, wherein when the fluctuation layer, quantum well layer and strain transition layer are grown, two TMIn source bottles are connected in series, the TMIn source bottle close to the reaction chamber is set to a bottle pressure of 200mbar-300mbar during growth, and the TMIn source bottle far from the reaction chamber is set to a pressure of 800mbar-1000mbar during growth, and the growth of a single cycle structure specifically includes the following steps:

[0043] (a) Growth of fluctuation layer: the temperature of the reaction chamber is set to 690℃±10℃, TMIn, AsH3 are introduced, and InAs material with a thickness of 5nm-10nm is grown, after the growth of the fluctuation layer, TMIn is turned off, and the temperature is kept constant at 700℃-720℃, TMGa and AsH3 are introduced during the annealing process, the flow rate of TMGa is set to 40sccm-60sccm, the flow rate of AsH3 is set to 400sccm-600sccm, and the annealing time is 4min; by means of the cracking effect of InAs at high temperature, the broken In bonds can react with Ga and As atoms on the surface of the epitaxial layer to form an InGaAs nucleation buffer layer, which can prevent the random aggregation of In atoms to form high-In and low-In regions and cause uneven local states during the growth of a conventional InGaAs quantum well structure; the InAs fluctuation layer is undoped;

[0044] (b) Growth of quantum well layer: the temperature of the reaction chamber is set to 690℃±10℃, TMGa, TMIn, and AsH3 are introduced, and the material grown is In x2 Ga 1-x2 As quantum well layer, the thickness of a single quantum well In x2 Ga 1-x2 As is 5nm-8nm, wherein the value of x2 is 0.13-0.20; the quantum well is undoped;

[0045] (c) Growth of strain transition layer: the temperature of the reaction chamber is set to 690℃±10℃, TMIn, TMGa, AsH3, and PH3 are introduced, and In x1 Ga 1-x1 AsP material with a thickness of 20nm-30nm is grown, wherein the initial In component x1 is set to 0.15, then x1 gradually decreases from 0.15 to 0 during the growth of the strain transition layer, and the rate of gradual change of the component x1 is 0.01 / s; at the same time, the initial PH3 flow rate during the growth of the strain transition layer is set to 300sccm, then the PH3 flow rate gradually increases from 300sccm to 600sccm during the growth process, and the rate of gradual change is 5sccm / s; the strain transition layer is undoped; on the one hand, the lattice size is reduced by reducing the In component to reduce the compressive strain, and on the other hand, the strain form is slowly transitioned from compressive strain to tensile strain by compensating with P element, which solves the problem of sudden strain mutation from compressive stress to tensile strain between the well / barrier in a conventional 940nm infrared LED, and avoids the problem of spectral double peaks caused by energy band splitting due to sudden strain mutation;

[0046] (d) Growth of quantum barrier layer: the temperature of the reaction chamber is set to 690℃±10℃, TMAl, TMGa, AsH3, and PH3 are introduced, and the material grown is (Al y3 Ga 1-y3 )0.5 As 0.5 P quantum barrier layer, single quantum barrier layer (Al y3 Ga 1-y3 ) 0.5 As 0.5 P, wherein y3 is in the range of 0.3-0.5; the quantum barrier is undoped.

[0047] (6) Growth of P-type confinement layer: the reaction chamber is set to a temperature of 690℃±10℃, TMGa, TMAl, and AsH3 are introduced, and Al y4 Ga 1-y4 As material is grown, wherein y4 is in the range of 0.25-0.50, CCl4 is used as P-type dopant, and the doping concentration is 1×10 18 cm -3 -2×10 18 cm -3 .

[0048] (7) Growth of P-type current spreading layer: the reaction chamber is set to a temperature of 690℃±10℃, TMGa, TMAl, and AsH3 are introduced, and Al y5 Ga 1-y5 As material is grown, wherein y5 is in the range of 0.1-0.15, CCl4 is used as P-type dopant, and the doping concentration is 0.7×10 18 cm -3 -1.5×10 18 cm -3 .

[0049] (8) Growth of P-face contact layer: the reaction chamber is set to a temperature of 600℃±10℃, TMGa and AsH3 are introduced, and GaAs contact layer material is grown, with a thickness of 50nm-100nm, CCl4 is used as P-type dopant, and the doping concentration is 0.5×10 20 cm -3 -2×10 20 cm -3 .

[0050] (9) Wafer taking: after the growth is completed, the temperature of the MOCVD reaction chamber is reduced to 110℃, then the pressure is adjusted to 1000mbar, the reaction chamber is opened, and the epitaxial wafer is taken out.

[0051] In order to further illustrate the present application, the present application is described in detail below in conjunction with specific examples.

[0052] Example 1

[0053] A preparation method of an infrared LED epitaxial wafer with improved spectrum, specifically comprising the following steps:

[0054] (1) MOCVD is performed in a pure H2 atmosphere with a low pressure of 50 mbar, the reaction chamber is set to a temperature of 400°C, then an N-type GaAs substrate is transferred into the reaction chamber through a mechanical hand transfer bin, and then rapidly heated to 700°C and maintained at 700°C for 5 min.

[0055] (2) Growth of an N-type GaAs buffer layer: the reaction chamber is set to a temperature of 690°C, TMGa and AsH3 are introduced, a GaAs buffer layer material with a thickness of 200 nm is grown, SiH4 is used as an N-type dopant, and the doping concentration is 1×10 18 cm -3 .

[0056] (3) Growth of an N-type current expansion layer: the reaction chamber is set to a temperature of 690°C, TMGa, TMAl and AsH3 are introduced, Al 0.1 Ga 0.9 As material with a thickness of 3000 nm is grown, SiH4 is used as an N-type dopant, and the doping concentration is 1×10 18 cm -3 .

[0057] (4) Growth of an N-type confinement layer: the reaction chamber is set to a temperature of 720°C, TMGa, TMAl and AsH3 are introduced, Al 0.3 Ga 0.7 As material with a thickness of 400 nm is grown, SiH4 is used as an N-type dopant, and the doping concentration is 2×10 18 cm -3 .

[0058] (5) Growth of a partial pressure single-peak light-emitting layer: the light-emitting layer is a periodic structure sequentially grown by a fluctuation layer, a quantum well layer, a strain transition layer and a quantum barrier layer, and the cycle number is 11 pairs, wherein when the fluctuation layer, the quantum well layer and the strain transition layer are grown, two TMIn source bottles are connected in series, one TMIn source bottle close to the reaction chamber is set to a bottle pressure of 300 mbar during growth, and the other TMIn source bottle away from the reaction chamber is set to a pressure of 1000 mbar during growth, and the growth of a single cycle structure specifically comprises the following steps:

[0059] (a) Growth of a fluctuation layer: the reaction chamber temperature is set to 690°C, TMIn and AsH3 are introduced, and InAs material with a thickness of 5 nm is grown, then TMIn is turned off after the growth of the fluctuation layer, and annealing is performed at 720°C, TMGa and AsH3 are introduced during the annealing process, the flow rate of TMGa is set to 60 sccm, the flow rate of AsH3 is set to 400 sccm, and the annealing time is 4 min; the InAs fluctuation layer is undoped;

[0060] (b) Growth of quantum well layer: set the temperature of the reaction chamber to 690 °C, and introduce TMGa, TMIn, and AsH3. The material grown is In 0.13 Ga 0.87 As quantum well layer, with a single quantum well In 0.13 Ga 0.87 As layer having a thickness of 6 nm, and the quantum well is undoped.

[0061] (c) Growth of strain transition layer: set the temperature of the reaction chamber to 690 °C ± 10 °C, and introduce TMIn, TMGa, AsH3, and PH3. The material grown is In x1 Ga 1-x1 AsP having a thickness of 23 nm, wherein the initial In component x1 is set to a value of 0.15, and then during the growth of the strain transition layer, x1 gradually decreases from 0.15 to 0 at a rate of 0.01 / s; simultaneously, the initial PH3 flow during growth of the strain transition layer is set to 300 sccm, and then during the growth, the PH3 flow gradually increases from 300 sccm to 600 sccm at a rate of 5 sccm / s; the strain transition layer is undoped.

[0062] (d) Growth of quantum barrier layer: set the temperature of the reaction chamber to 690 °C, and introduce TMAl, TMGa, AsH3, and PH3. The material grown is (Al 0.4 Ga 0.6 ) 0.5 As 0.5 P quantum barrier layer, with a single quantum barrier (Al 0.4 Ga 0.6 ) 0.5 As 0.5 P layer having a thickness of 25 nm, and the quantum barrier is undoped.

[0063] (6) Growth of P-type confinement layer: set the temperature of the reaction chamber to 700 °C, and introduce TMGa, TMAl, and AsH3. The material grown is Al 0.45 Ga 0.55 As having a thickness of 500 nm, with CCl4 used as a P-type dopant, and a doping concentration of 2 x 1018cm 18 cm -3 .

[0064] (7) Growth of P-type current spreading layer: set the temperature of the reaction chamber to 690 °C, and introduce TMGa, TMAl, and AsH3. The material grown is Al 0.1 Ga 0.9 As having a thickness of 7000 nm, with CCl4 used as a P-type dopant, and a doping concentration of 1.0 x 1018cm 18 cm-3 .

[0065] (8) Growth of P surface contact layer: the reaction chamber is set to a temperature of 610 DEG C, TMGa and AsH3 are introduced, a GaAs contact layer material with a thickness of 80 nm is grown, CCl4 is used as a P-type dopant, and the doping concentration is 1 x 1018 cm-3. 20 cm -3 .

[0066] (9) Wafer taking: after the growth is completed, the temperature of the MOCVD reaction chamber is reduced to 110 DEG C, then the pressure is adjusted to 1000 mbar, the reaction chamber is opened, and the epitaxial wafer is taken out.

[0067] Comparative Example 1

[0068] A conventional 940 nm infrared LED epitaxial wafer is prepared by using a conventional method, and a structure diagram thereof is shown in Figure 1 .

[0069] Test Example

[0070] The infrared LED obtained in Example 1 and the conventional 940 nm infrared LED obtained in Comparative Example 1 are tested for the emission spectrum under a 20 mA current, and the results are shown in Figure 4 and Figure 5 .

[0071] Comparison Figure 4 and Figure 5 It can be seen that the spectrum of the infrared LED prepared by the present application is single and stable, and there is no two emission peaks, which is a single peak; while the spectrum of the conventional 940 nm infrared LED has two emission peak values, that is, there is a double peak phenomenon. It is shown that the technical solution of the present application can effectively solve the problem of double emission peaks of the conventional 940 nm infrared LED due to unstable structure and process.

[0072] Finally, it needs to be emphasized that the above description is only the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An improved spectral infrared LED epiwafer, characterized by, The infrared LED epitaxial wafer grows epitaxial layers from an N-type GaAs substrate, and grows N-type GaAs buffer layer, N-type current expansion layer, N-type confinement layer, voltage division type single-peak light emitting layer, P-type confinement layer, P-type current expansion layer, P-face contact layer in turn from bottom to top; The voltage division type single-peak light emitting layer is a periodic structure grown in turn by fluctuation layer, quantum well layer, strain transition layer and quantum barrier layer; The material of the fluctuation layer is InAs, and the thickness in each cycle is 5nm-10nm; the fluctuation layer is non-doped; The material of the strain transition layer is In x1 Ga 1-x1 AsP, the thickness of which is 20-30 nm in each cycle, wherein the initial In component x1 is set to 0.15, x1 gradually decreases from 0.15 to 0 during the growth of the strain transition layer, and the rate of gradual change of x1 is 0.01 / s.

2. The improved spectral infrared LED epitaxial wafer according to claim 1, wherein, The cycle logarithm of the periodic structure is 6 pairs-12 pairs.

3. The method of claim 1 or 2, wherein the method further comprises: N-type GaAs buffer layer, N-type current expansion layer, N-type confinement layer, voltage division type single-peak light emitting layer, P-type confinement layer, P-type current expansion layer, P-face contact layer are grown in turn on the N-type GaAs substrate by using MOCVD equipment; The voltage division type single-peak light emitting layer is a periodic structure grown in turn by fluctuation layer, quantum well layer, strain transition layer and quantum barrier layer; The fluctuation layer, quantum well layer and strain transition layer are all grown by using voltage division type double TMIn source series process.

4. The method of claim 3, wherein the method further comprises: The voltage division type double TMIn source series process is that two bottles of TMIn source are connected in series, one bottle of TMIn source close to the reaction chamber is set to 200mbar-300mbar during growth, and the other bottle of TMIn source far from the reaction chamber is set to 800mbar-1000mbar during growth.

5. The method of claim 3, wherein the method further comprises: The growth step of the fluctuation layer is that the reaction chamber temperature is set to 690℃±10℃, TMIn and AsH3 are input, and InAs material with a thickness of 5nm-10nm is grown.

6. The method of claim 3, wherein the method further comprises: After the growth of the fluctuation layer is completed, constant temperature annealing is carried out at 700℃-720℃, and TMGa and AsH3 are input during the annealing process, wherein the flow rate of TMGa is set to 40sccm-60sccm, and the flow rate of AsH3 is set to 400sccm-600sccm.

7. The method for preparing an infrared LED epitaxial wafer with improved spectrum according to claim 3, characterized in that, The growth step of the strain transition layer is: setting the reaction chamber temperature to 690℃±10℃, inputting TMIn, TMGa, AsH3, PH3, growing In x1 Ga 1-x1 AsP material.

8. The method for preparing an infrared LED epitaxial wafer with improved spectrum according to claim 3, characterized in that, The initial PH3 flow rate is set to 300sccm during the growth of the strain transition layer, and then the PH3 flow rate gradually increases from 300sccm to 600sccm during the growth of the strain transition layer, wherein the gradual change rate is 5sccm / s.

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