Light emitting diode capable of improving luminous efficiency and preparation method thereof

Abstract

The embodiment of the invention provides a light emitting diode capable of improving light emitting efficiency and a preparation method thereof, and belongs to the technical field of semiconductors. The light-emitting diode comprises an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer, a first P-type current expansion layer and a P-type window layer which are stacked in sequence, wherein the doping concentration of the first P-type current expansion layer is smaller than that of the P-type window layer. According to the embodiment of the invention, the uniformity of carrier injection can be improved, and the luminous efficiency of an LED is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a light emitting diode with improved light emitting efficiency and a preparation method thereof. Background Art

[0002] Light Emitting Diode (LED) has been widely used in various light source fields such as backlight, lighting, and landscaping due to its small size, long service life, rich colors, and low energy consumption.

[0003] In the related art, an LED includes a light-emitting structure, a P-type current spreading layer, and a P-type window layer stacked in sequence, wherein the doping concentration of the P-type current spreading layer is greater than the doping concentration of the P-type window layer.

[0004] However, since the greater the doping concentration, the greater the carrier concentration and the smaller the resistance, the higher the doping concentration of the P-type current spreading layer will result in a smaller resistance of the P-type current spreading layer. When the current is transmitted to the P-type current spreading layer, it will be transmitted downward quickly in the vertical direction, affecting the lateral expansion effect of the current in the P-type current spreading layer, thereby affecting the luminous efficiency of the LED. Summary of the invention

[0005] The embodiment of the present disclosure provides a light emitting diode with improved luminous efficiency and a method for manufacturing the same, which can improve the uniformity of carrier injection and improve the luminous efficiency of the LED. The technical solution is as follows:

[0006] On the one hand, a light-emitting diode is provided, comprising an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer, a first P-type current spreading layer and a P-type window layer stacked in sequence, wherein the doping concentration of the first P-type current spreading layer is less than the doping concentration of the P-type window layer.

[0007] Optionally, the doping concentration of the first P-type current spreading layer gradually increases along a direction from the P-type semiconductor layer to the P-type window layer.

[0008] Optionally, the doping concentration of the first P-type current spreading layer is 3*10 17 / cm 3 Up to 5*10 17 / cm 3 .

[0009] Optionally, the first P-type current spreading layer includes a first P-type sublayer, a second P-type sublayer and a third P-type sublayer stacked in sequence in a direction away from the P-type semiconductor layer, the doping concentration of the first P-type sublayer is less than the doping concentration of the second P-type sublayer, and the doping concentration of the second P-type sublayer is less than the doping concentration of the third P-type sublayer; the thickness of the first P-type sublayer is less than the thickness of the third P-type sublayer, and the thickness of the third P-type sublayer is less than the thickness of the second P-type sublayer.

[0010] Optionally, the doping concentration of the P-type window layer is 2*10 18 / cm 3 Up to 3*10 18 / cm 3 .

[0011] Optionally, the first P-type current spreading layer and the P-type window layer are both Mg-doped GaP layers.

[0012] On the other hand, a method for preparing a light-emitting diode is provided, comprising: forming a light-emitting layer on an N-type semiconductor layer; forming a P-type semiconductor layer on the light-emitting layer; and forming a first P-type current spreading layer and a P-type window layer stacked in sequence on the P-type semiconductor layer, wherein the doping concentration of the first P-type current spreading layer is less than the doping concentration of the P-type window layer.

[0013] Optionally, the first P-type current spreading layer and the P-type window layer stacked in sequence are formed on the P-type semiconductor layer, including: forming an undoped current spreading material layer on the P-type semiconductor layer; forming the P-type window layer on the current spreading material layer, and allowing the doped elements in the P-type window layer to diffuse into the current spreading material layer to obtain the first P-type current spreading layer.

[0014] Optionally, the current spreading material layer includes a first sublayer, a second sublayer and a third sublayer stacked in sequence in a direction away from the P-type semiconductor layer, the growth rate of the first sublayer is smaller than the growth rate of the second sublayer, and the growth rate of the second sublayer is smaller than the growth rate of the third sublayer.

[0015] Optionally, the growth rate of the first sublayer is 1 angstrom / s to 5 angstroms / s, the growth rate of the second sublayer is 5 angstroms / s to 15 angstroms / s, and the growth rate of the third sublayer is 15 angstroms / s to 20 angstroms / s.

[0016] The technical solution provided by the embodiments of the present disclosure brings the following beneficial effects:

[0017] In the disclosed embodiment, the doping concentration of the first P-type current spreading layer is less than the doping concentration of the P-type window layer. Since the lower the doping concentration, the lower the concentration of carriers and the greater the resistance, that is, the resistance of the P-type window layer is smaller, the current can be quickly transferred to the first P-type current spreading layer in the longitudinal direction when passing through the P-type window layer. The resistance of the first P-type current spreading layer is larger, and the first P-type current spreading layer will play a better role in hindering the longitudinal transfer of the current, which is conducive to making the current better expand horizontally to various regions in the first P-type current spreading layer and then transfer longitudinally, thereby improving the uniformity of carrier injection and improving the luminous efficiency of the LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is a schematic diagram of the structure of an LED provided by an embodiment of the present disclosure;

[0020] Figure 2 is a flow chart of a method for preparing an LED provided by an embodiment of the present disclosure;

[0021] Figure 3 is a flow chart of another method for preparing an LED provided by an embodiment of the present disclosure;

[0022] Figure 4 This is a schematic diagram of a structure of an LED manufacturing process provided by an embodiment of the present disclosure;

[0023] Figure 5 is a schematic diagram of the brightness of LEDs in a control group provided by an embodiment of the present disclosure;

[0024] Figure 6 It is a schematic diagram of the brightness of an experimental group of LEDs provided in an embodiment of the present disclosure.

[0025] Reference numerals:

[0026] 10: N-type semiconductor layer; 11: N-type confinement layer; 12: N-type waveguide layer; 20: light-emitting layer; 30: P-type semiconductor layer; 31: P-type confinement layer; 32: P-type waveguide layer; 40: first P-type current spreading layer; 41: first P-type sublayer; 411: first sublayer; 42: second P-type sublayer; 421: second sublayer; 43: third P-type sublayer; 431: third sublayer; 50: P-type window layer; 60: substrate; 70: distributed Bragg reflection (DBR) layer; 80: second P-type current spreading layer; 90: P-type contact layer. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0028] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" and similar words mean that the elements or objects appearing before "include" include the elements or objects listed after "include" and their equivalents, and do not exclude other elements or objects. Words such as "connect" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0029] Figure 1 is a schematic diagram of the structure of an LED provided by an embodiment of the present disclosure. The LED may be a red-yellow LED, such as Figure 1 As shown, the LED includes an N-type semiconductor layer 10, a light-emitting layer 20, a P-type semiconductor layer 30, a first P-type current spreading layer 40 and a P-type window layer 50 stacked in sequence. The doping concentration of the first P-type current spreading layer 40 is less than the doping concentration of the P-type window layer 50.

[0030] In the disclosed embodiment, the doping concentration of the first P-type current spreading layer 40 is less than the doping concentration of the P-type window layer 50. Since the lower the doping concentration, the lower the concentration of carriers and the greater the resistance, that is, the resistance of the P-type window layer 50 is smaller, the current can be quickly transferred to the first P-type current spreading layer 40 in the longitudinal direction when passing through the P-type window layer 50. The resistance of the first P-type current spreading layer 40 is larger, and the first P-type current spreading layer 40 will play a better role in hindering the longitudinal transfer of the current, which is conducive to making the current better spread horizontally to various regions in the first P-type current spreading layer 40 and then transfer longitudinally, thereby improving the uniformity of carrier injection and improving the luminous efficiency of the LED.

[0031] It should be noted that, since the doping types of the first P-type current spreading layer 40 and the P-type window layer 50 are both P-type doping, the above-mentioned carriers are holes.

[0032] Optionally, the doping concentration of the first P-type current spreading layer 40 gradually increases along the direction from the P-type semiconductor layer 30 to the P-type window layer 50. That is, in the first P-type current spreading layer 40, the doping concentration of the portion closest to the P-type window layer 50 is the largest, and the doping concentration of the portion closest to the P-type semiconductor layer 30 is the smallest. Here, the doping concentration gradually increases may refer to a linear increase in the doping concentration, or to a gradient increase in the doping concentration, etc.

[0033] In this way, the concentration of carriers in the part of the first P-type current spreading layer 40 far from the P-type semiconductor layer 30 can be relatively large, ensuring that the number of carriers and the injection efficiency are high. In addition, the concentration of carriers in the part of the first P-type current spreading layer 40 close to the P-type semiconductor layer 30 is relatively small, which can ensure that the current expansion capability of the part of the first P-type current spreading layer 40 close to the P-type semiconductor layer 30 is good. Thus, while ensuring that the number of carriers and the injection efficiency are high, the uniformity of carrier injection is improved, so as to effectively improve the luminous efficiency of the LED.

[0034] Optionally, the doping concentration of the first P-type current spreading layer 40 is 3*10 17 / cm 3 Up to 5*10 17 / cm 3 If the concentration of the first P-type current spreading layer 40 is too low, the number of carriers and the injection efficiency may be low, affecting the radiation recombination efficiency of the carriers; if the doping concentration of the first P-type current spreading layer 40 is too high, the lateral expansion capability of the first P-type current spreading layer 40 for the current may be affected. The doping concentration of the first P-type current spreading layer 40 within this range can ensure a high number of carriers and injection efficiency, while improving the lateral expansion capability of the current.

[0035] For example, along the direction from the P-type semiconductor layer 30 to the P-type window layer 50, the doping concentration of the first P-type current spreading layer 40 may be from 3*10 17 / cm 3 Gradually increase to 5*10 17 / cm 3 .

[0036] Optionally, the thickness of the first P-type current spreading layer 40 is 2700 angstroms to 3300 angstroms. When the thickness of the first P-type current spreading layer 40 is within this range, the first P-type current spreading layer 40 has a better lateral capability to current.

[0037] For example, the thickness of the first P-type current spreading layer 40 may be 2700 angstroms, 3000 angstroms, or 3300 angstroms.

[0038] Optionally, the first P-type current spreading layer 40 may be made of an undoped current spreading material layer.

[0039] For example, the first P-type current spreading layer 40 may be obtained by diffusing the doping elements in the P-type window layer 50 downward to the undoped current spreading material layer under high temperature conditions.

[0040] Since the doping elements in the P-type window layer 50 are easy to diffuse downward under high temperature conditions, if the first P-type current spreading layer 40 is first grown by doping the P-type elements, and then the P-type window layer 50 is grown on the first P-type current spreading layer 40, the doping elements in the P-type window layer 50 diffuse into the first P-type current spreading layer 40, which may cause the doping concentration of the first P-type current spreading layer 40 to be too high. Making the first P-type current spreading layer 40 by an undoped current spreading material layer can ensure that the doping concentration of the first P-type current spreading layer 40 is low and the carrier injection efficiency is high.

[0041] like Figure 1 As shown, the first P-type current spreading layer 40 includes a first P-type sublayer 41 , a second P-type sublayer 42 , and a third P-type sublayer 43 which are sequentially stacked in a direction away from the P-type semiconductor layer 30 .

[0042] Exemplarily, the doping concentration of the first P-type sublayer 41 is less than the doping concentration of the second P-type sublayer 42 , and the doping concentration of the second P-type sublayer 42 is less than the doping concentration of the third P-type sublayer 43 .

[0043] In one possible embodiment, the doping concentration of the first P-type sublayer 41 gradually increases along the direction from the P-type semiconductor layer 30 to the P-type window layer 50, the doping concentration of the second P-type sublayer 42 gradually increases along the direction from the P-type semiconductor layer 30 to the P-type window layer 50, the doping concentration of the third P-type sublayer 43 gradually increases along the direction from the P-type semiconductor layer 30 to the P-type window layer 50, and the maximum doping concentration of the first P-type sublayer 41 is less than the minimum doping concentration of the second P-type sublayer 42, and the maximum doping concentration of the second P-type sublayer 42 is less than the minimum doping concentration of the third P-type sublayer.

[0044] In another possible implementation, the doping concentration of the first P-type sublayer 41, the doping concentration of the second P-type sublayer 42, and the doping concentration of the third P-type sublayer 43 are all fixed. That is, the doping concentrations of the various parts of the first P-type sublayer 41 are the same, the doping concentrations of the various parts of the second P-type sublayer 42 are the same, and the doping concentrations of the various parts of the third P-type sublayer 43 are the same. The doping concentration relationship of the three P-type sublayers satisfies that the doping concentration of the first P-type sublayer 41 is less than the doping concentration of the second P-type sublayer 42, and the doping concentration of the second P-type sublayer 42 is less than the doping concentration of the third P-type sublayer 43.

[0045] Exemplarily, the first P-type sublayer 41, the second P-type sublayer 42, and the third P-type sublayer 43 may also have different growth rates. For example, the growth rate of the first P-type sublayer 41 is less than the growth rate of the second P-type sublayer 42, and the growth rate of the second P-type sublayer 42 is less than the growth rate of the third P-type sublayer 43.

[0046] Optionally, the thickness of the first P-type sublayer 41 is smaller than the thickness of the third P-type sublayer 43 , and the thickness of the third P-type sublayer 43 is smaller than the thickness of the second P-type sublayer 42 .

[0047] Since the doping concentration of the first P-type sublayer 41 close to the P-type semiconductor layer 30 is relatively small and the thickness of the first P-type sublayer 41 is relatively small, the longitudinal resistance of the first P-type sublayer 41 can be relatively large, the current expansion capability of the first P-type sublayer 41 is relatively good, and the number of carriers and the injection efficiency will not be affected by the excessive thickness of the first P-type sublayer 41; the doping concentration of the third P-type sublayer 43 close to the P-type window layer 50 is relatively large, the number of carriers and the injection efficiency in the third P-type sublayer 43 can be relatively high, the thickness of the third P-type sublayer is at an intermediate level, and the lateral expansion of the current will not be affected by the excessive thickness of the third P-type sublayer 43; the doping concentration of the second P-type sublayer 42 located between the first P-type sublayer 41 and the third P-type sublayer 43 is at an intermediate level, the number of carriers, the injection efficiency and the current expansion capability in the second P-type sublayer 42 are relatively good, and the maximum thickness of the second P-type sublayer 42 can ensure that the number of carriers, the injection efficiency and the current expansion capability of the first P-type current expansion layer 40 as a whole are better.

[0048] Optionally, the thickness of the first P-type sublayer 41 is 200 angstroms to 400 angstroms.

[0049] By way of example, the thickness of the first P-type sublayer 41 may be 200 angstroms, 300 angstroms, 400 angstroms, etc.

[0050] Optionally, the thickness of the second P-type sublayer 42 is 1700 angstroms to 1900 angstroms.

[0051] By way of example, the thickness of the second P-type sublayer 42 may be 1700 angstroms, 1800 angstroms, or 1900 angstroms.

[0052] Optionally, the thickness of the third P-type sublayer 43 is 800 angstroms to 1000 angstroms.

[0053] By way of example, the thickness of the third P-type sublayer 43 may be 800 angstroms, 900 angstroms, or 1000 angstroms.

[0054] Optionally, the first P-type current spreading layer 40 is a Mg-doped GaP layer. The Mg-doped GaP layer has good current spreading capability, which is beneficial to improving the uniformity of carrier injection.

[0055] Since the first P-type current spreading layer 40 is grown at a relatively high temperature, the first P-type current spreading layer 40 may also be referred to as a high-temperature current spreading layer.

[0056] Optionally, the doping concentration of the P-type window layer 50 is 2*10 18 / cm 3 Up to 3*10 18 / cm 3 In this way, the P-type window layer 50 can cooperate with the first P-type current spreading layer 40 to improve the lateral expansion capability of the current and improve the luminous efficiency of the LED. In addition, the higher concentration of the P-type window layer 50 is conducive to the diffusion of the doped elements in the P-type window layer 50 downward to the undoped current spreading material layer under high temperature conditions to obtain the first P-type current spreading layer 40.

[0057] For example, the doping concentration of the P-type window layer 50 may be 2*10 18 / cm 3 , 2.5*10 18 / cm 3 or 3*10 18 / cm 3 wait.

[0058] Optionally, the thickness of the P-type window layer 50 is 3.5 μm to 4.5 μm.

[0059] For example, the thickness of the P-type window layer 50 may be 3.5 μm, 4 μm, or 4.5 μm.

[0060] Optionally, the P-type window layer 50 is a Mg-doped GaP window layer. In this way, not only can the lateral expansion capability of the current be ensured to be good, but also Mg can easily diffuse downward under high temperature conditions, which is conducive to growing the P-type window layer 50 at high temperature, so that Mg diffuses downward to the undoped current expansion material layer under high temperature conditions to obtain the first P-type current expansion layer 40 with a lower doping concentration.

[0061] like Figure 1 As shown, the LED further includes a substrate 60 , which is located on a side of the N-type semiconductor layer 10 away from the light emitting layer 20 .

[0062] Optionally, the substrate 60 is a GaAs substrate, a sapphire substrate, a Si substrate or a SiC substrate.

[0063] Optionally, the LED further includes a DBR layer 70 , and the DBR layer 70 is located between the substrate 60 and the N-type semiconductor layer 10 .

[0064] Optionally, the DBR layer 70 is an N-type DBR layer.

[0065] Exemplarily, the DBR layer 70 includes a plurality of pairs of N-type AlAs layers and N-type AlGaAs layers periodically and alternately stacked, and the number of periods may be 10 to 70. For example, the DBR layer 70 may include 30 pairs of N-type AlAs layers and N-type AlGaAs layers periodically and alternately stacked.

[0066] like Figure 1 As shown, the N-type semiconductor layer 10 includes an N-type confinement layer 11 and an N-type waveguide layer 12 which are sequentially stacked in a direction away from the substrate 60 .

[0067] Optionally, the N-type confinement layer 11 is an N-type AlInP confinement layer.

[0068] Optionally, the N-type waveguide layer 12 is an N-type AlGaInP waveguide layer.

[0069] Optionally, the light emitting layer 20 is a multi-quantum well layer, including a plurality of pairs of AlGaInP quantum barrier layers and GaInP quantum well layers stacked alternately.

[0070] Exemplarily, the light emitting layer 20 may include 10 to 30 pairs of AlGaInP quantum barrier layers and GaInP quantum well layers stacked alternately. For example, it may be 20 pairs of AlGaInP quantum barrier layers and GaInP quantum well layers stacked alternately, or other pairs, which is not limited in the present disclosure.

[0071] like Figure 1 As shown, the P-type semiconductor layer 30 includes a P-type waveguide layer 32 and a P-type confinement layer 31 which are sequentially stacked in a direction away from the light emitting layer 20 .

[0072] Optionally, the P-type confinement layer 31 is a P-type AlInP confinement layer.

[0073] Optionally, the P-type waveguide layer 32 is a P-type AlGaInP waveguide layer.

[0074] Optionally, the LED further includes a second P-type current spreading layer 80 , and the second P-type current spreading layer 80 is located between the first P-type current spreading layer 40 and the P-type semiconductor layer 30 .

[0075] Optionally, the second P-type current spreading layer 80 may be a Mg-doped GaP current spreading layer. Since the Mg-doped GaP current spreading layer is grown at a relatively low temperature, the second P-type current spreading layer 80 may also be referred to as a low-temperature current spreading layer. The low-temperature current spreading layer may effectively improve stress and defects caused by lattice mismatch and improve the growth quality of the current spreading layer.

[0076] Optionally, the LED further includes a P-type contact layer 90 , and the P-type contact layer 90 is located on a surface of the P-type window layer 50 away from the first P-type current spreading layer 40 .

[0077] Optionally, the P-type contact layer 90 is a P-type GaP contact layer.

[0078] It should be noted that Figure 1 The film layer structure of the LED shown and the material of the above film layer are only used as an example. In other embodiments, the LED may also include more or fewer film layer structures, and the materials of each film layer can be selected according to actual needs, etc., and there is no limitation on this publicly.

[0079] Figure 2 FIG. 1 is a flow chart of a method for preparing an LED provided by an embodiment of the present disclosure. Figure 2 As shown, the preparation method comprises:

[0080] In step S101 , a light emitting layer is formed on an N-type semiconductor layer.

[0081] In step S102 , a P-type semiconductor layer is formed on the light emitting layer.

[0082] In step S103 , a first P-type current spreading layer and a P-type window layer stacked in sequence are formed on the P-type semiconductor layer.

[0083] Wherein, the doping concentration of the first P-type current spreading layer is less than the doping concentration of the P-type window layer.

[0084] In the disclosed embodiment, the doping concentration of the first P-type current spreading layer is less than the doping concentration of the P-type window layer. Since the lower the doping concentration, the lower the concentration of carriers and the greater the resistance, that is, the resistance of the P-type window layer is smaller, the current can be quickly transferred to the first P-type current spreading layer in the longitudinal direction when passing through the P-type window layer. The resistance of the first P-type current spreading layer is larger, and the first P-type current spreading layer will play a better role in hindering the longitudinal transfer of the current, which is conducive to making the current better expand horizontally to various regions in the first P-type current spreading layer and then transfer longitudinally, thereby improving the uniformity of carrier injection and improving the luminous efficiency of the LED.

[0085] Figure 3 FIG. 1 is a flow chart of another method for preparing an LED provided by an embodiment of the present disclosure. Figure 3 As shown, the preparation method comprises:

[0086] In step S201 , a DBR layer, an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer are sequentially stacked on a substrate.

[0087] For example, the substrate may be placed in a metal-organic chemical vapor deposition (MOCVD) reaction chamber to form a DBR layer, an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer stacked in sequence on the substrate.

[0088] In step S202 , an undoped current spreading material layer is formed on the P-type semiconductor layer.

[0089] Figure 4 Schematic diagram of a structure of an LED manufacturing process provided by an embodiment of the present disclosure. Figure 4 As shown, the current spreading material layer includes a first sublayer 411 , a second sublayer 421 and a third sublayer 431 which are sequentially stacked in a direction away from the P-type semiconductor layer 30 .

[0090] Optionally, the first sublayer 411 , the second sublayer 421 , and the third sublayer 431 are all GaP layers.

[0091] In the embodiment of the present disclosure, the thickness of the first sublayer 411 is the same as the thickness of the first P-type sublayer, the thickness of the second sublayer 421 is the same as the thickness of the second P-type sublayer, and the thickness of the third sublayer 431 is the same as the thickness of the third P-type sublayer. Figure 1 The relevant embodiments will not be described in detail here.

[0092] Optionally, step S202 may include the following steps:

[0093] In the first step, a first sublayer is formed on the P-type semiconductor layer.

[0094] Optionally, the growth temperature of the first sub-layer 411 is 750° C. to 800° C.

[0095] Exemplarily, the temperature of the reaction chamber may be controlled to be 780° C., and a gallium source, phosphine and hydrogen may be introduced to form an undoped GaP layer on the P-type semiconductor layer 30 to obtain the first sublayer 411 .

[0096] Optionally, the growth rate of the first sublayer 411 is 1 angstrom / s to 5 angstroms / s. The low growth rate of the first sublayer 411 can ensure good quality of the first sublayer 411, and is conducive to the diffusion of doping elements in the P-type window layer to the first sublayer 411 in subsequent steps, so that the doping concentration of the first P-type sublayer is small, ensuring good current expansion capability of the first P-type sublayer.

[0097] For example, the growth rate of the first sub-layer 411 may be 1 angstrom / s, 3 angstroms / s, 5 angstroms / s, etc.

[0098] Optionally, the growth time of the first sub-layer 411 is 1 min to 5 min.

[0099] For example, the growth time of the first sub-layer 411 may be 1 min, 3 min, 5 min, etc.

[0100] In the second step, a second sub-layer is formed on the first sub-layer.

[0101] Optionally, the growth temperature of the second sub-layer 421 is 750° C. to 800° C.

[0102] Exemplarily, the temperature of the reaction chamber may be controlled to be 780° C., and a gallium source, phosphine, and hydrogen may be introduced to form an undoped GaP layer on the first sublayer 411 to obtain the second sublayer 421 .

[0103] Optionally, the growth rate of the first sub-layer 411 is lower than the growth rate of the second sub-layer 421. In this way, the growth quality of the second sub-layer 421 can be ensured to be good while improving the production efficiency.

[0104] Optionally, the growth rate of the second sub-layer 421 gradually increases along the direction from the P-type semiconductor layer 30 to the P-type window layer 50 .

[0105] Optionally, the growth rate of the second sublayer 421 is 5 angstroms / s to 15 angstroms / s. In this way, the doping elements in the P-type window layer can be diffused to the second sublayer 421 in subsequent steps, so that the carrier injection capability and current expansion capability of the obtained second P-type sublayer are both good.

[0106] For example, along the direction from the P-type semiconductor layer 30 to the P-type window layer 50 , the growth rate of the second sublayer 421 may be gradually increased from 5 angstroms / s to 15 angstroms / s.

[0107] Optionally, the growth time of the second sub-layer 421 is 2 min to 4 min.

[0108] For example, the growth time of the first sub-layer 411 may be 2 min, 3 min, 4 min, etc.

[0109] In the third step, a third sub-layer is formed on the second sub-layer.

[0110] Optionally, the growth temperature of the third sub-layer 431 is 750° C. to 800° C.

[0111] Exemplarily, the temperature of the reaction chamber may be controlled to be 780° C., and a gallium source, phosphine, and hydrogen may be introduced to form an undoped GaP layer on the second sublayer 421 to obtain the third sublayer 431 .

[0112] Optionally, the growth rate of the second sub-layer 421 is lower than the growth rate of the third sub-layer 431. In this way, the growth quality of the third sub-layer 431 can be ensured to be good while further improving the production efficiency.

[0113] Optionally, the growth rate of the third sublayer 431 is 15 angstroms / s to 20 angstroms / s. The high growth rate of the third sublayer 431 can ensure the good quality of the third sublayer 431, and is conducive to the diffusion of the doping elements in the P-type window layer to the third sublayer 431 in the subsequent steps, so that the doping concentration of the obtained third P-type sublayer is relatively large, ensuring the good carrier injection capability of the third P-type sublayer.

[0114] For example, the growth rate of the third sub-layer 431 may be 15 angstroms / s, 17 angstroms / s, or 20 angstroms / s.

[0115] Optionally, the growth time of the third sub-layer 431 is 0.5 min to 1.5 min.

[0116] For example, the growth time of the third sub-layer 431 may be 0.5 min, 1 min, or 1.5 min.

[0117] Through the above three steps, an undoped current spreading material layer can be formed on the P-type semiconductor layer 30 .

[0118] Optionally, before performing step S202 , a second P-type current spreading layer 80 may be formed on the P-type semiconductor layer 30 .

[0119] Exemplarily, the temperature of the reaction chamber can be controlled to 730° C., and a magnesium source, a gallium source, phosphine and hydrogen are introduced to form a Mg-doped GaP current spreading layer on the P-type semiconductor layer 30 to obtain the second P-type current spreading layer 80 .

[0120] For example, after the second P-type current spreading layer 80 is formed, the introduction of the magnesium source may be stopped, and only phosphine and hydrogen may be introduced for 5 minutes to increase the temperature of the reaction chamber.

[0121] It should be noted that, when the second P-type current spreading layer 80 is formed, the step S202 is to form an undoped current spreading material layer on the second P-type current spreading layer 80 .

[0122] In step S203, a P-type window layer is formed on the current spreading material layer, and the doping elements in the P-type window layer are diffused into the current spreading material layer to obtain a first P-type current spreading layer.

[0123] Optionally, the growth temperature of the P-type window layer is 750° C. to 800° C. Since the doping elements in the P-type window layer are easy to diffuse downward under high temperature conditions, the doping elements in the P-type window layer can diffuse downward to the current spreading material layer better within this relatively high temperature range, thereby making the doping concentration distribution of the first P-type current spreading layer better, ensuring that the first P-type current spreading layer has a better ability to laterally expand the current.

[0124] Exemplarily, the temperature of the reaction chamber can be controlled to 780°C, and a magnesium source, a gallium source, phosphine and hydrogen are introduced to form a Mg-doped GaP window layer on the current spreading material layer to obtain a P-type window layer, and the doping elements in the P-type window layer are diffused into the current spreading material layer to obtain a first P-type current spreading layer.

[0125] Optionally, the growth time of the P-type window layer 50 is 23 minutes to 28 minutes. The growth time within this range is also conducive to ensuring a good doping concentration distribution of the first P-type current spreading layer, which can improve the current spreading capability of the first P-type current spreading layer and improve the uniformity of carrier injection.

[0126] For example, the growth time of the P-type window layer 50 may be 23 minutes, 25 minutes, or 28 minutes.

[0127] Through the above steps S202 to S203 , a first P-type current spreading layer and a P-type window layer stacked in sequence can be formed on the P-type semiconductor layer.

[0128] In step S204 , a P-type contact layer is formed on the P-type window layer.

[0129] Optionally, the material, doping concentration, thickness and number of cycles of each layer can be found in Figure 1 The detailed description of the related embodiments is omitted here.

[0130] The average brightness of the LED provided by the embodiment of the present disclosure is exemplarily described below. Figure 1 The LED in the related embodiment adopts Figure 3 The control group LED refers to the LED in the related art. The difference between the control group LED and the experimental group LED is that the doping concentration and formation method of the high-temperature current spreading layer are different. The high-temperature current spreading layer of the control group LED is formed by doping P-type elements during the film growth process, and the doping concentration of the high-temperature current spreading layer of the control group LED is higher.

[0131] The brightness of multiple control group LEDs and multiple experimental group LEDs are tested respectively. Figure 5 Schematic diagram of the brightness of a control group LED provided in an embodiment of the present disclosure. Figure 5 Part (a) shows the brightness of the first control group LED. Figure 5 Part (b) shows the brightness of the second control group LED. Figure 5 In the figure, the brightness of the control group LED is distinguished by different colors, and a bar graph is used to represent the brightness distribution of the control group LED in the brightness range of 100mcd to 200mcd. The luminous output power (LOP) is used in the bar graph to represent the brightness of the LED. Figure 5 As shown, the brightness of the LEDs in the first control group is mostly in the range of about 150mcd, and the brightness of the LEDs in the second control group is mostly in the range of about 140mcd and 150mcd.

[0132] Figure 6 It is a schematic diagram of the brightness of an experimental group of LEDs provided in an embodiment of the present disclosure. Figure 6 Part (a) shows the brightness of the LEDs in the first experimental group. Figure 6 Part (b) shows the brightness of the LEDs in the second experimental group. Figure 6 In the figure, different colors are used to distinguish the brightness of the experimental group LEDs, and a bar graph is used to represent the brightness distribution of the experimental group LEDs in the brightness range of 100mcd to 200mcd. The bar graph uses LOP to represent the brightness of the LEDs. Figure 6 As shown, the brightness of the LEDs in the first experimental group is mostly in the range of about 160mcd, and the brightness of the LEDs in the second experimental group is mostly in the range of about 160mcd.

[0133] Table 1 is the average brightness test results of the control group LED and the experimental group LED. After testing, it was found that the average brightness of the two experimental group LEDs was 162.9mcd and 162.8mcd, and the average brightness of the two control group LEDs was 154.2mcd and 149.1mcd, that is, the average brightness of the experimental group LEDs was higher than the average brightness of the control group LEDs. Therefore, the LED provided by the embodiment of the present disclosure improves the luminous efficiency of the LED.

[0134] Table 1 Average brightness test results

[0135]

[0136] The above description does not limit the present disclosure in any form. Although the present disclosure has been disclosed as above through the embodiments, it is not used to limit the present disclosure. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present disclosure. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure still falls within the scope of the technical solution of the present disclosure.

Claims

1. A light emitting diode, characterized in that: The invention comprises an N-type semiconductor layer (10), a light-emitting layer (20), a P-type semiconductor layer (30), a first P-type current spreading layer (40) and a P-type window layer (50) which are stacked in sequence, wherein the doping concentration of the first P-type current spreading layer (40) is lower than the doping concentration of the P-type window layer (50).

2. The light emitting diode according to claim 1, characterized in that: The doping concentration of the first P-type current spreading layer (40) gradually increases along a direction from the P-type semiconductor layer (30) to the P-type window layer (50).

3. The light emitting diode according to claim 2, characterized in that: The doping concentration of the first P-type current spreading layer (40) is 3*10 17 / cm 3 Up to 5*10 17 / cm 3 .

4. The light emitting diode according to claim 2, characterized in that: The first P-type current spreading layer (40) comprises a first P-type sublayer (41), a second P-type sublayer (42) and a third P-type sublayer (43) which are sequentially stacked in a direction away from the P-type semiconductor layer (30), The doping concentration of the first P-type sublayer (41) is less than the doping concentration of the second P-type sublayer (42), and the doping concentration of the second P-type sublayer (42) is less than the doping concentration of the third P-type sublayer (43); The thickness of the first P-type sublayer (41) is smaller than the thickness of the third P-type sublayer (43), and the thickness of the third P-type sublayer (43) is smaller than the thickness of the second P-type sublayer (42).

5. The light emitting diode according to any one of claims 1 to 4, characterized in that: The doping concentration of the P-type window layer (50) is 2*10 18 / cm 3 Up to 3*10 18 / cm 3 .

6. The light emitting diode according to any one of claims 1 to 4, characterized in that: The first P-type current spreading layer (40) and the P-type window layer (50) are both Mg-doped GaP layers.

7. A method for preparing a light emitting diode, characterized in that: include: forming a light emitting layer (20) on the N-type semiconductor layer (10); forming a P-type semiconductor layer (30) on the light-emitting layer (20); A first P-type current spreading layer (40) and a P-type window layer (50) stacked in sequence are formed on the P-type semiconductor layer (30), wherein the doping concentration of the first P-type current spreading layer (40) is lower than the doping concentration of the P-type window layer (50).

8. The preparation method according to claim 7, characterized in that: The first P-type current spreading layer (40) and the P-type window layer (50) are sequentially stacked on the P-type semiconductor layer (30), comprising: forming an undoped current spreading material layer on the P-type semiconductor layer (30); The P-type window layer (50) is formed on the current spreading material layer, and the doping elements in the P-type window layer (50) are diffused into the current spreading material layer to obtain the first P-type current spreading layer (40).

9. The preparation method according to claim 8, characterized in that: The current spreading material layer comprises a first sublayer (411), a second sublayer (421) and a third sublayer (431) which are stacked in sequence in a direction away from the P-type semiconductor layer (30), the growth rate of the first sublayer (411) being lower than the growth rate of the second sublayer (421), and the growth rate of the second sublayer (421) being lower than the growth rate of the third sublayer (431).

10. The preparation method according to claim 9, characterized in that: The growth rate of the first sublayer (411) is 1 angstrom / s to 5 angstroms / s, the growth rate of the second sublayer (421) is 5 angstroms / s to 15 angstroms / s, and the growth rate of the third sublayer (431) is 15 angstroms / s to 20 angstroms / s.

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