A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode

Abstract

The invention relates to a method for regulating a built-in electric field in an active region of a deep ultraviolet light-emitting diode, belonging to the technical field of semiconductor photodiodes. The method comprises, from bottom to top, a substrate, a buffer layer, an n-type semiconductor electron injection layer, a multi-quantum well active layer, a p-type electron blocking layer, a p-type semiconductor hole injection layer, a p-type contact layer, a p-type electrode, and an n-type electrode. The multi-quantum well active layer comprises a plurality of periodically grown units, each unit comprises a quantum well and quantum barriers on both sides of the quantum well, Mg is doped on a side close to the quantum well in the quantum barriers on the upper side of the quantum well, Si is doped on a side close to the quantum well in the quantum barriers on the lower side of the quantum well, and each quantum barrier is not fully doped. The built-in electric field of a deep ultraviolet light-emitting diode is regulated by a selective doping method, so as to solve the problems of wavelength red shift and efficiency attenuation caused by an excessively large built-in electric field, and at the same time, the electron and hole injection of the DUV LED is regulated, so as to improve the photoelectric performance of the DUV LED by suppressing electron leakage and enhancing hole injection.

Description

Technical Field

[0001] The invention relates to a method for regulating a built-in electric field in an active region of a deep ultraviolet light-emitting diode, and belongs to the technical field of semiconductor photodiodes. Background Art

[0002] AlGaN material is a wide bandgap direct bandgap semiconductor with adjustable bandgap width in the range of 3.4eV to 6.2eV. The corresponding emission wavelength range can be changed from 365nm to 200nm. It is the most suitable material for preparing deep ultraviolet light-emitting diodes. Compared with traditional ultraviolet pump lamps, AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) have the advantages of less environmental harm, low operating voltage, low energy consumption and long service life. In addition, DUV LEDs have great application value and broad market space in high-density optical storage, sterilization and disinfection, air and water purification, biochemical experiments, anti-counterfeiting detection, display communication, medical testing, etc.

[0003] After nearly a decade of development, with the joint efforts of many researchers and the industry, AlGaN-based DUV LEDs have made important progress in epitaxial growth, device technology and structural design. In terms of carrier injection, many structures have well solved the problem of low hole injection efficiency caused by the introduction of an electron blocking layer (EBL). However, AlGaN materials have a wurtzite crystal structure, and there is spontaneous polarization in the crystal. And because there is a lattice mismatch between the quantum well and the quantum barrier, a piezoelectric polarization effect will be triggered. Both of these polarizations will cause a strong built-in electric field inside the quantum well, causing its energy band to bend, reducing the transition energy, and then causing a red shift in the spectrum, limiting the spectral range of the DUV LED. At the same time, the built-in electric field will cause the separation of electrons and holes in spatial distribution, and the wave function overlap rate will decrease, reducing the radiation recombination rate and luminous efficiency of the DUV LED.

[0004] Therefore, regulating the built-in electric field in the active area of ​​DUV LEDs and reducing the wavelength red shift and efficiency attenuation caused by the built-in electric field are issues that need to be urgently addressed in engineering and science.

[0005] A Chinese patent document (publication number CN 113782652 A) discloses a quantum barrier doped ultraviolet LED epitaxial wafer and a manufacturing method thereof, and shows a method for doping ultraviolet LED quantum barriers, wherein at least one group of quantum barrier layers near one end of the N-type AlGaN layer is doped with Si elements, and the remaining quantum barrier layers are doped with Mg elements, so that electrons and holes can be better injected into the middle of the active region. However, for the quantum wells sandwiched by the Si-doped quantum barrier layers, although the distribution of holes in the quantum wells is improved because the polarization electric field is weakened, the distribution of electrons in the quantum wells will be attracted by the positive electric center formed after the Si in the quantum barrier is ionized and closer to one side of the quantum barrier. Similarly, for the quantum wells sandwiched by the Mg-doped quantum barrier layers, although the distribution of electrons in the quantum wells is improved because the polarization electric field is weakened, the distribution of holes in the quantum wells will be attracted by the negative electric center formed after the Mg in the quantum barrier is ionized and closer to one side of the quantum barrier.

[0006] A Chinese patent document (publication number CN 106159047 A) discloses a light-emitting diode epitaxial structure with a PN-doped quantum barrier and a manufacturing method thereof, and demonstrates a light-emitting diode structure with a micro-PN junction quantum barrier. Compared with conventional light-emitting diodes, this invention partially shields the polarization electric field by using a built-in electric field in the PN double-doped GaN barrier layer, thereby reducing the total electric field in the quantum well and increasing the overlap rate of the electron-hole wave function. However, the research of the present invention is based on the InGaN-based quantum well. For deep ultraviolet light-emitting diodes, due to the strong electron injection capability, the PN double doping close together will cause the height of the effective electron barrier to be affected, making it easier to leak to the P-type region. At the same time, the electric field weakened in the quantum barrier cannot act on the quantum well efficiently, and the quantum well is the main area where electrons and holes recombine. Summary of the invention

[0007] Generally, in order to form an active region that enables electrons and holes to recombine, Al x Ga 1-x N layer and Al y Ga 1-yAn N-layer multi-period composite structure of quantum wells and quantum barriers, where x < y. However, due to the difference in the Al and Ga components between the quantum wells and quantum barriers, charges introduced by the piezoelectric polarization effect will be generated at the interface between the quantum wells and quantum barriers. Looking at each quantum well, the quantum barrier in the

[0001] crystal direction and its interaction generate positive interface charges, and the quantum barrier in the [000-1] crystal direction and its interaction generate negative interface charges. A polarization electric field along the [000-1] direction is formed between the positive and negative charges, causing the spatial separation of electrons and holes in the quantum well, thereby leading to a decrease in the radiative recombination rate. The decrease in the radiative recombination rate means low optical power and external quantum efficiency of the DUV LED, which is very disadvantageous for realizing high-efficiency light-emitting diodes.

[0008] Aiming at the deficiencies of the prior art, the present invention provides a method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode. By means of selective doping, the built-in electric field of the DUV LED is regulated to solve the problems of wavelength redshift and efficiency attenuation caused by an excessive built-in electric field. At the same time, the electron and hole injection of the DUV LED is regulated, and the optoelectronic performance of the DUV LED is improved by suppressing electron leakage and enhancing hole injection.

[0009] In order to weaken the influence brought by the built-in electric field of the DUV LED, the present invention proposes a method for regulating the electric field in the active region of an AlGaN-based DUV LED by doping Si and Mg respectively in the quantum barriers on both sides of each quantum well.

[0010] The technical solution of the present invention is as follows:

[0011] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode, the deep ultraviolet light-emitting diode sequentially includes a substrate, a buffer layer, an n-type semiconductor electron injection layer, a multi-quantum well active layer, a p-type electron blocking layer, a p-type semiconductor hole injection layer, a p-type contact layer, a p-type electrode from bottom to top, and an n-type electrode is provided above the other side of the n-type semiconductor electron injection layer. The multi-quantum well active layer includes a plurality of units grown periodically, each unit includes a quantum well and quantum barriers on both the upper and lower sides of the quantum well, the unit is grown repeatedly 3-10 times, the quantum barrier on the upper side of the quantum well is doped with Mg near the side close to the quantum well, the quantum barrier on the lower side of the quantum well is doped with Si near the side close to the quantum well, and each quantum barrier is not fully doped.

[0012] Preferably, the substrate is one of silicon carbide (SiC), sapphire, gallium nitride (GaN), aluminum nitride (AlN), or silicon (Si). And for a polar substrate, it can be divided into a polar plane, a non-polar plane, and a semi-polar plane substrate according to the different epitaxial growth directions, thus affecting the growth direction of the light-emitting diode epitaxial layer.

[0013] Preferably, the material of the buffer layer is Alx1 Ga 1-x1 N, where 0≤x1≤1, 0≤1-x1≤1.

[0014] Preferably, the material of the n-type semiconductor electron injection layer is n-Al x2 Ga 1-x2 N, among which n-Al x2 Ga 1-x2 The value range of the Al component x2 of N is: 0≤x2≤1, 0≤1-x2≤1.

[0015] Preferably, the multi-quantum well active layer is an alternately grown Al x3 Ga 1-x3 N quantum barrier layer and Al x4 Ga 1-x4 N quantum well layer, further preferably, the Al component x3 in the quantum barrier layer is greater than the Al component x4 in the quantum well layer.

[0016] Further preferably, the Al composition in the barrier layer is 0.5≤x3≤1, 0<x4<x3.

[0017] Preferably, the thickness of Mg doping in each quantum barrier is 0.01 to 0.4 times the thickness of the quantum barrier, and the Mg doping concentration can be 1e16 to 1e20; the thickness of Si doping in each quantum barrier is 0.01 to 0.4 times the thickness of the quantum barrier, and the Si doping concentration can be 1e16 to 1e20. Note that in order to best weaken the polarization electric field in the quantum well and prevent Mg atoms from falling into the quantum well to form non-radiative recombination centers, we set the thickness of Mg doping to 0.01 to 0.4 times the thickness of the quantum barrier, and use undoped quantum barriers to prevent Mg atoms from falling into the quantum well.

[0018] Further preferably, according to the TCAD simulation results, the optimal value of the doping thickness is 0.3 times the thickness of the quantum barrier, the thickness of Mg doping in each quantum barrier is 0.3 times the thickness of the quantum barrier, and the thickness of Si doping in each quantum barrier is 0.3 times the thickness of the quantum barrier. By partially doping the quantum barrier with n-type and p-type, the polarization electric field is weakened. The Mg acceptor is ionized under the action of the applied voltage and polarization charge, and a negative charge center is left after the hole is released, which weakens the electric field generated by the positive polarization charge between the quantum well and the quantum barrier. At the same time, the Si donor is ionized under the condition of an applied voltage, and a positive charge center is left after the electron is released, which weakens the electric field generated by the negative polarization charge between the quantum well and the quantum barrier. Not only that, by doping the quantum barrier, the barrier height of electrons and holes at the quantum barrier is greatly reduced, so that the concentration of electrons and holes in the quantum well is improved. And the electron barrier at the EBL is also increased, so that the electrons leaking into the p-type hole region are greatly reduced.

[0019] Preferably, the material of the p-type electron blocking layer is Al x5 Ga 1-x5 N, where 0≤x5≤1, 0≤1-x5≤1.

[0020] More preferably, x5≥x3, that is, the Al component of the p-type electron blocking layer is ≥ the Al component of the barrier layer.

[0021] Preferably, the material of the p-type semiconductor hole injection layer is Al x6 Ga 1-x6 N, where 0≤x6≤1, 0≤1-x6≤1.

[0022] Preferably, the material of the p-type contact layer is Al x7 Ga 1-x7 N, where 0≤x7≤1, 0≤1-x7≤1.

[0023] Preferably, the material of the p-type electrode is metal Ni / Au, Cr / Au, Ni / Al or Pt / Au, which are different metal layers deposited successively.

[0024] Preferably, the material of the n-type electrode is metal Ti / Al / Ti / Au, Al / Au or Cr / Au, which are different metal layers deposited successively.

[0025] The introduction of n-type and p-type doped layer structures in the quantum barriers of deep ultraviolet light-emitting diodes can be accomplished in MOCVD by using H2 as a carrier gas and introducing Si source and Mg source when growing different doped layers, thereby completing the growth of n-type and p-type quantum barriers and simultaneously completing the growth of 3 to 10 AlGaN / AlGaN multiple quantum wells.

[0026] Preferably, the preparation process of the method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode is specifically as follows:

[0027] (1) In the MOCVD reaction chamber, Al is grown on the substrate surface. x1 Ga 1-x1 N buffer layer, the substrate material can be one of silicon carbide (SiC), sapphire, gallium nitride (GaN), aluminum nitride (AlN), or silicon (Si);

[0028] (2) In a MOCVD reaction chamber, an n-type electron injection layer is grown on the buffer layer in step (1), wherein the material of the n-type electron injection layer is AlGaN material, and an n-type semiconductor is formed by introducing Si doping;

[0029] (3) In the MOCVD reaction chamber, the temperature is set to 1000°C to 1300°C, the pressure is set to 20 to 80 Torr, and the V / III ratio is set to 100 to 4000, and Al is alternately grown on the n-type semiconductor electron injection layer in step (2). x3 Ga 1-x3 N quantum barrier layer and Al x4 Ga 1-x4 N quantum well layer thereby forms an active region, wherein the Al component x3 in the quantum barrier layer is greater than the Al component x4 in the quantum well layer; when growing a portion of the quantum barrier close to one side of the quantum well, the time for introducing the Si source is controlled according to the desired doping thickness; at the same time, when growing a portion of the quantum barrier close to one side of the quantum well, the time for introducing the Mg source is controlled according to the desired doping thickness;

[0030] (4) In the MOCVD reaction chamber, an AlGaN electron blocking layer is continuously grown on the surface of the multi-quantum well active layer, and p-type doping is performed by introducing Mg impurities;

[0031] (5) In a MOCVD reaction chamber, a p-type AlGaN hole injection layer is then grown on the surface of the p-type electron blocking layer obtained in step (4), and p-type doping is performed by introducing Mg impurities;

[0032] (6) In the MOCVD reaction chamber, a p-type contact layer is then grown on the surface of the hole injection layer obtained in step (5), the material of which is GaN, and p-type heavy doping is performed by introducing Mg impurities;

[0033] (7) After the growth is completed, high temperature annealing treatment is carried out in a N2 atmosphere for about 20 minutes to remove hydrogen and activate the acceptor activity and p-type conductivity of Mg;

[0034] (8) Then, the mesa of the AlGaN-based deep ultraviolet light-emitting diode is etched out through photolithography, etching and other steps, and a portion of the n-type electron injection layer is exposed. Then, the p-type electrode, current spreading layer and n-type electrode are manufactured through processes such as photolithography and electron beam evaporation.

[0035] Preferably, in the above-mentioned MOCVD epitaxial growth process of AlGaN-based deep ultraviolet light-emitting diodes, trimethylgallium or triethylgallium is used as the gallium source, trimethylaluminum is used as the aluminum source; ammonia is used as the nitrogen source, silane is used as the Si impurity source, and bismuth magnesium is used as the Mg impurity source.

[0036] Finally, the present invention uses TCAD simulation to assist in analyzing the effects of n-type and p-type quantum barriers on the performance of DUV LEDs, which can save a lot of time and cost and better guide the subsequent DUV LED preparation process.

[0037] The present invention provides a DUV LED structure with a selectively doped quantum barrier structure, and proposes a method of selectively doping the quantum barrier with Mg and Si to reduce the built-in electric field in the active region of the DUV LED. The technology can effectively weaken the influence of the polarization electric field on the spatial distribution of electrons and holes, and can adjust the potential barrier by doping, thereby increasing the injection of electrons and holes, so as to achieve the results of obtaining a high radiation recombination rate, external quantum efficiency and optical power.

[0038] The beneficial effects of the present invention are:

[0039] The present invention introduces n-type and p-type doped quantum barriers into the epitaxial structure of a traditional deep ultraviolet light-emitting diode, and the doping concentration can be lightly doped or heavily doped. The doping of the n-type and p-type layers in the quantum barrier is selective doping rather than full doping, and the doping thickness of each type of doping can be 0.01 to 0.5 times the total thickness of the quantum barrier. The n-type layer is in the lower part of each quantum well, and the p-type layer is in the upper part of the quantum well. The introduction of this structure can reduce the influence of the polarization electric field on the spatial distribution of electrons and holes, increase the overlap rate of the electron and hole wave functions, and thus improve the radiation recombination rate of the deep ultraviolet light-emitting diode, so that it can obtain better photoelectric characteristics.

[0040] At the same time, the introduction of this structure can reduce the effective barrier height of the quantum barrier to electrons and increase the effective barrier height of the EBL to electrons, reduce the effective barrier height of the quantum barrier and EBL to holes, thereby improving the injection efficiency of holes while suppressing electron leakage, improving the radiation recombination rate in the active area, and ultimately improving the external quantum efficiency and optical power of the deep ultraviolet light-emitting diode. The introduction of this structure has almost no effect on the voltage-current characteristic curve of the DUV LED, which means that under the same power loss, the deep ultraviolet light-emitting diode can obtain better light output characteristics, thereby proving the high efficiency of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the structure of an AlGaN-based deep ultraviolet light-emitting diode with n-type and p-type doped quantum barrier structures proposed by the present invention;

[0042] Figure 2 It is a schematic diagram of the structure of the multi-quantum well active layer of the present invention;

[0043] Figure 3 This is a schematic diagram of quantum barrier doping of the present invention;

[0044] Wherein: 1. substrate, 2. buffer layer, 3. n-type semiconductor electron injection layer, 4. multi-quantum well active layer; 5. p-type electron blocking layer, 6. p-type semiconductor hole injection layer, 7. p-type contact layer, 8. p-type electrode, 9. n-type electrode;

[0045] 41. A unit consisting of a quantum well and quantum barriers on the upper and lower sides of the quantum well; 411. A portion of the quantum barrier that is doped with Mg, 412. A portion of the quantum barrier that is doped with Si;

[0046] Figure 4 This is a comparison diagram of the electric field intensity in the active region of an AlGaN-based standard deep ultraviolet light-emitting diode and the deep ultraviolet light-emitting diode proposed in the present invention. The positive direction of the electric field is the

[0001] crystal direction.

[0047] Figure 5(a) is a comparison of the distribution diagrams of the electron concentration in the active layer of a standard deep ultraviolet light-emitting diode and the deep ultraviolet light-emitting diode proposed in the present invention. For a clearer comparison, the horizontal axis corresponding to the electron concentration of the deep ultraviolet light-emitting diode proposed in the present invention is shifted by 4 nm relative to the horizontal axis of the electron concentration of the standard deep ultraviolet light-emitting diode.

[0048] Figure 5(b) is a comparison of the distribution diagrams of the hole concentration in the active layer of a standard deep ultraviolet light-emitting diode and the deep ultraviolet light-emitting diode proposed in the present invention. For a clearer comparison, the horizontal axis corresponding to the hole concentration of the deep ultraviolet light-emitting diode proposed in the present invention is shifted by 4 nm relative to the horizontal axis of the hole concentration of the standard deep ultraviolet light-emitting diode.

[0049] FIG6( a ) is a graph showing the relationship between light power and current density of a standard deep ultraviolet light emitting diode and a specific embodiment of the deep ultraviolet light emitting diode proposed in the present invention.

[0050] FIG6( b ) is a graph showing the relationship between the external quantum efficiency and the current density of a standard deep ultraviolet light emitting diode and a specific embodiment of the deep ultraviolet light emitting diode proposed in the present invention.

[0051] Figure 7 Graph showing the relationship between applied voltage and current density for a standard deep ultraviolet light emitting diode and an example of the deep ultraviolet light emitting diode proposed in the present invention. DETAILED DESCRIPTION

[0052] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0053] Embodiment 1:

[0054] Figure 1 , Figure 2 and Figure 3 The present invention provides a schematic structural diagram of an AlGaN-based deep ultraviolet light-emitting diode with n-type and p-type doped quantum barrier structures.

[0055] A method for regulating the built-in electric field of a deep ultraviolet light-emitting diode active region, the deep ultraviolet light-emitting diode comprises, from bottom to top, a substrate 1, a buffer layer 2, an n-type semiconductor electron injection layer 3, a multi-quantum well active layer 4, a p-type electron blocking layer 5, a p-type semiconductor hole injection layer 6, a p-type contact layer 7, a p-type electrode 8, and an n-type electrode 9 is arranged above the other side of the n-type semiconductor electron injection layer.

[0056] In the above structure, the material of substrate 1 is SiC substrate, the material of buffer layer 2 is AlN with a thickness of 200nm, and the material of n-type semiconductor electron injection layer 3 is n-Al 0.6 Ga 0.4 N, the doping concentration is selected as 8e18cm -3 The material of the multi-quantum well active layer 4 is an alternately grown quantum barrier layer Al 0.57 Ga 0.43 N and quantum well layer Al 0.45 Ga 0.55 N, the thickness is 10nm and 3nm respectively, the number of periods is 5 periods, and the material in contact with the p-type electron blocking layer 5 is a quantum barrier layer Al 0.57 Ga 0.43 N. In each quantum well layer Al 0.45 Ga 0.55 Above N, the doping thickness is 3nm and the doping concentration of Mg is 5e18cm -3 The p-type quantum barrier layer 411 has a doping thickness of 0.3 times the thickness of the quantum barrier layer. 0.45 Ga 0.55 Below N, the doping thickness is 3nm and the doping Si concentration is 5e18cm -3 The n-type quantum barrier layer 412 has a doping thickness of 0.3 times the thickness of the quantum barrier layer. The material of the p-type electron blocking layer 5 is p-Al 0.6 Ga 0.4 N, doping concentration is 2e19 cm -3 , with a thickness of 10 nm, and the material of the p-type semiconductor hole injection layer 6 is p-Al 0.4 Ga 0.6 N, doping concentration is 4e19cm -3 , with a thickness of 50 nm. The material of the p-type contact layer 7 is heavily doped p-GaN with a doping concentration of 1e20 cm -3 , thickness is 50nm, the material of the p-type electrode 8 is Ni / Au (5 / 5nm), which is Ni layer + Au layer. A 5nmNi metal layer is deposited first, and then a 5nmAu metal layer is deposited. The material of the n-type electrode 9 is Ti / Al / Ti / Au (30 / 120 / 30 / 200nm). Similarly, different metal layers of different thicknesses are deposited in sequence.

[0057] The specific preparation process is as follows:

[0058] (1) In the MOCVD reaction chamber, Al is grown on the substrate surface. x1 Ga 1-x1 N buffer layers, where x1=1;

[0059] (2) In the MOCVD reaction chamber, an n-type semiconductor electron injection layer is grown on the buffer layer in step (1), and the material of the n-type semiconductor electron injection layer is n-Al 0.6 Ga 0.4 N, and forms an n-type semiconductor by introducing Si doping;

[0060] (3) In the MOCVD reaction chamber, the temperature is set to 1100°C, the pressure is 56 Torr, and the V / III ratio is 200. Al is grown alternately on the n-type semiconductor electron injection layer in step (2). 0.57 Ga 0.43 N quantum barrier layer and Al 0.45 Ga 0.55 N quantum well layer to form an active region; when the part 412 near the quantum well side in the growth quantum barrier is controlled, the Si source is introduced for a time of Al 0.57 Ga 0.43 The last three tenths of the growth time of the N quantum barrier; at the same time, when the part 411 near the quantum well in the growing quantum barrier is controlled, the introduction time of the Mg source is controlled to be Al 0.57 Ga 0.43 The first three tenths of the growth time of the N quantum barriers; the thickness of Mg doped in each quantum barrier is 0.3 times the thickness of the quantum barrier, i.e. 3 nm; the Mg doping concentration is 5e18 cm -3 ; The thickness of Si doping in each quantum barrier is 0.3 times the thickness of the quantum barrier, i.e. 3nm; the Si doping concentration is 5e18cm -3 ;

[0061] (4) In the MOCVD reaction chamber, the AlGaN electron blocking layer p-Al2O3 is grown on the surface of the multi-quantum well active layer. 0.6 Ga 0.4 N, and p-type doping is performed by introducing Mg impurities;

[0062] (5) In the MOCVD reaction chamber, a p-type AlGaN hole injection layer is then grown on the surface of the p-type electron blocking layer obtained in step (4). The material of the p-type semiconductor hole injection layer is p-Al 0.4 Ga 0.6 N, and p-type doping is performed by introducing Mg impurities;

[0063] (6) In the MOCVD reaction chamber, a p-type contact layer is then grown on the surface of the hole injection layer. The material of the p-type contact layer is p-GaN, and p-type heavy doping is performed by introducing Mg impurities;

[0064] (7) After the growth is completed, a high temperature annealing treatment at 1100°C is carried out in a N2 atmosphere for about 20 minutes to remove hydrogen and activate the acceptor activity and p-type conductivity of Mg;

[0065] (8) Then, the mesa of the AlGaN-based deep ultraviolet light-emitting diode is etched out through photolithography, etching and other steps, and a portion of the n-type electron injection layer is exposed. Then, the p-type electrode, current spreading layer and n-type electrode are manufactured through processes such as photolithography and electron beam evaporation.

[0066] In the above-mentioned MOCVD epitaxial growth process of AlGaN-based deep ultraviolet light-emitting diodes, trimethylgallium is used as a gallium source, trimethylaluminum is used as an aluminum source; ammonia is used as a nitrogen source, silane is used as a Si impurity source, and bismuth magnesium is used as a Mg impurity source.

[0067] Depend on Figure 4 It can be seen that the electric field strength of the deep ultraviolet light-emitting diode proposed in the present invention at the quantum well is almost 50% of that of the standard deep ultraviolet light-emitting diode. This is because the acceptor center left after Mg ionization and the donor center left after Si ionization weaken the intensity of the polarization electric field caused by spontaneous polarization and piezoelectric polarization.

[0068] As can be seen from Figure 5(a), compared with the standard deep ultraviolet light-emitting diode, the electron concentration in the active region of the deep ultraviolet light-emitting diode proposed by the present invention has increased significantly. As can be seen from Figure 5(b), compared with the standard deep ultraviolet light-emitting diode, the hole concentration in the active region of the deep ultraviolet light-emitting diode proposed by the present invention has increased significantly. As can be seen from Figure 6(a), the optical power of the deep ultraviolet light-emitting diode proposed by the present invention has increased by 28% compared with the standard deep ultraviolet light-emitting diode (the current density is 170A / cm 2 From Figure 6(b), it can be seen that the external quantum efficiency decay rate of the deep ultraviolet light-emitting diode proposed in the present invention (current density is 170A / cm 2 Under the condition of ), it is reduced by 42.51% compared with the standard deep ultraviolet light-emitting diode. Figure 7 It can be found that the invention does not affect the electrical characteristics of the deep ultraviolet light emitting diode, which means that the deep ultraviolet light emitting diode proposed in the present invention can generate higher light power output under the same power consumption.

[0069] Embodiment 2:

[0070] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode. The other steps in this embodiment are the same as those in embodiment 1, except that the thickness of the quantum barrier doping layers 411 and 412 in this embodiment is changed to 2nm, and the doping concentration of the doping layer is changed to 2e17.

[0071] Embodiment 3:

[0072] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode. The other steps in this embodiment are the same as those in embodiment 1, except that the doping concentration of the quantum barrier doping layers 411 and 412 in this embodiment is changed to 2e17.

[0073] Embodiment 4:

[0074] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode, wherein the steps are as described in Example 1, except that the material of the multi-quantum well active layer 4 is an alternately grown quantum barrier layer Al 0.57 Ga 0.43 N and quantum well layer Al 0.45 Ga 0.55 N, the number of cycles is 3 cycles.

[0075] Embodiment 5:

[0076] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode, wherein the steps are as described in Example 1, except that the material of the multi-quantum well active layer 4 is an alternately grown quantum barrier layer Al 0.57 Ga 0.43 N and quantum well layer Al 0.45 Ga 0.55 N, the number of cycles is 10 cycles.

[0077] Embodiment 6:

[0078] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode, wherein the steps are as described in Example 1, except that each quantum well layer Al 0.45 Ga 0.55 Above N, the doping thickness of the p-type quantum barrier layer 411 is 0.01 times the thickness of the quantum barrier layer. 0.45 Ga 0.55 Below N, the doping thickness of the n-type quantum barrier layer 412 is 0.01 times the thickness of the quantum barrier layer.

[0079] Embodiment 7:

[0080] A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode, wherein the steps are as described in Example 1, except that each quantum well layer Al 0.45 Ga 0.55Above N, the doping thickness of the p-type quantum barrier layer 411 is 0.4 times the thickness of the quantum barrier layer. 0.45 Ga 0.55 Below N, the doping thickness of the n-type quantum barrier layer 412 is 0.4 times the thickness of the quantum barrier layer.

[0081] The above-mentioned process is only a preferred embodiment of the present invention. It should be noted that, for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered as the protection scope of the present invention. Matters not covered by the present invention are known technologies.

Claims

1. A method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode, characterized in that: The deep ultraviolet light-emitting diode includes, from bottom to top, a substrate, a buffer layer, an n-type semiconductor electron injection layer, a multi-quantum well active layer, a p-type electron blocking layer, a p-type semiconductor hole injection layer, a p-type contact layer, a p-type electrode, and an n-type electrode is arranged on the other side of the n-type semiconductor electron injection layer. The multi-quantum well active layer includes a plurality of units grown periodically, each unit includes a quantum well and quantum barriers on the upper and lower sides of the quantum well, and the unit is repeatedly grown 3-10 times. The quantum barriers on the upper side of the quantum well are doped with Mg on one side close to the quantum well, and the quantum barriers on the lower side of the quantum well are doped with Si on one side close to the quantum well, and each quantum barrier is not fully doped. The thickness of Mg doping in each quantum barrier is 0.01 to 0.4 times the thickness of the quantum barrier, and the Mg doping concentration is 1e16 to 1e20; the thickness of Si doping in each quantum barrier is 0.01 to 0.4 times the thickness of the quantum barrier, and the Si doping concentration is 1e16 to 1e20.

2. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 1, characterized in that: The substrate is one of silicon carbide, sapphire, gallium nitride, aluminum nitride, or silicon.

3. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 1, characterized in that: The multi-quantum well active layer is an alternately grown Al x3 Ga 1-x3 N quantum barrier layer and Al x4 Ga 1-x4 N quantum well layer.

4. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 3, characterized in that: The Al composition x3 in the quantum barrier layer is greater than the Al composition x4 in the quantum well layer.

5. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 4, characterized in that: 0.5≤x3≤1, 0<x4<x3.

6. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 5, characterized in that: The thickness of Mg doping in each quantum barrier is 0.3 times the thickness of the quantum barrier, and the thickness of Si doping in each quantum barrier is 0.3 times the thickness of the quantum barrier.

7. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 3, characterized in that: Includes one or more of the following conditions: Ⅰ. The material of the buffer layer is Al x1 Ga 1-x1 N, where 0≤x1≤1, 0≤1-x1≤1; II. The material of the n-type semiconductor electron injection layer is n-Al x2 Ga 1-x2 N, among which n-Al x2 Ga 1-x2 The value range of Al component x2 of N is: 0≤x2≤1, 0≤1-x2≤1; III. The material of the p-type electron blocking layer is Al x5 Ga 1-x5 N, where 0≤x5≤1, 0≤1-x5≤1; IV. The material of the p-type semiconductor hole injection layer is Al x6 Ga 1-x6 N, where 0≤x6≤1, 0≤1-x6≤1; Ⅴ. The material of the p-type contact layer is Al x7 Ga 1-x7 N, where 0≤x7≤1, 0≤1-x7≤1; VI. The material of the p-type electrode is metal Ni / Au, Cr / Au, Ni / Al or Pt / Au, which are different metal layers deposited successively; VII. The material of the n-type electrode is metal Ti / Al / Ti / Au, Al / Au or Cr / Au, which are different metal layers deposited successively.

8. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 7, characterized in that: x5≥x3.

9. The method for regulating the built-in electric field in the active region of a deep ultraviolet light-emitting diode according to claim 7, characterized in that: The preparation process of the method for regulating the built-in electric field in the active area of ​​a deep ultraviolet light-emitting diode is as follows: (1) In the MOCVD reaction chamber, Al is grown on the substrate surface. x1 Ga 1-x1 N buffer layer; (2) In the MOCVD reaction chamber, an n-type semiconductor electron injection layer is grown on the buffer layer in step (1), and its material is n-Al x2 Ga 1-x2 N, and forms an n-type semiconductor by introducing Si doping; (3) In the MOCVD reaction chamber, the temperature is set to 1000°C to 1300°C, the pressure is set to 20 to 80 Torr, and the V / III ratio is set to 100 to 4000, and Al is alternately grown on the n-type semiconductor electron injection layer in step (2). x3 Ga 1-x3 N quantum barrier layer and Al x4 Ga 1-x4 N quantum well layer thereby forms an active region, wherein the Al component x3 in the quantum barrier layer is greater than the Al component x4 in the quantum well layer; when growing a portion of the quantum barrier close to one side of the quantum well, the time for introducing the Si source is controlled according to the desired doping thickness; at the same time, when growing a portion of the quantum barrier close to one side of the quantum well, the time for introducing the Mg source is controlled according to the desired doping thickness; (4) In the MOCVD reaction chamber, Al continues to grow on the surface of the multi-quantum well active layer. x5 Ga 1-x5 N electron blocking layer, and p-type doping is performed by introducing Mg impurities; (5) In the MOCVD reaction chamber, a p-type Al x6 Ga 1-x6 N hole injection layer, and p-type doping is performed by introducing Mg impurities; (6) In the MOCVD reaction chamber, a p-type contact layer is then grown on the surface of the hole injection layer obtained in step (5), and its material is Al x7 Ga 1-x7 N, and p-type heavy doping is performed by introducing Mg impurities; (7) After the growth is completed, high temperature annealing treatment is performed in a N2 atmosphere for 20 minutes to remove hydrogen and activate the acceptor activity and p-type conductivity of Mg; (8) Then, the mesa of the AlGaN-based deep ultraviolet light-emitting diode is etched out through photolithography and etching steps, and a portion of the n-type electron injection layer is exposed. Then, the p-type electrode, the current spreading layer and the n-type electrode are manufactured through photolithography and electron beam evaporation processes.

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