A light emitting diode with a stepped quantum well structure and a method for preparing the same

Abstract

The present invention discloses a light emitting diode with a ladder-type quantum well structure, comprising: an N-type electrode, a P-type electrode, a substrate, and an N-type conductive layer, a quantum well active region, a P-type electron blocking layer and a P-type conductive layer stacked on the substrate in sequence; wherein the N-type electrode is electrically connected to the N-type conductive layer; the P-type electrode is electrically connected to the P-type conductive layer; the quantum well active region comprises a quantum well layer and an Al2O3 layer stacked on the N-type conductive layer in sequence; 0.6 Ga 0.4 N quantum barrier layers; the quantum well layer is a step-type quantum well, and its thickness is 2nm. The present invention, by setting a quantum well active region, will not cause a very strong polarization electric field, thereby improving the energy band bending caused by the polarization effect, and increasing the overlap rate of the electron and hole wave functions, and ultimately improving the radiation recombination efficiency and luminescence efficiency of the diode.

Description

Technical Field

[0001] The invention relates to the technical field of diode structures, and more particularly to a light emitting diode with a stepped quantum well structure. Background Art

[0002] Since the beginning of the 21st century, the field of AlGaN-based deep ultraviolet LEDs has developed rapidly, and deep ultraviolet LEDs have demonstrated their very important technical application value in many aspects. However, the Al component in AlGaN-based deep ultraviolet LEDs is relatively high, and they have extremely strong polarization electric fields. The bending and deformation of the energy bands lead to a low overlap rate of electron and hole wave functions, low radiation recombination efficiency, and low luminous efficiency. Therefore, it is necessary to increase the overlap rate of electron and hole wave functions to solve the problem of low luminous efficiency.

[0003] However, on the one hand, in order to obtain high radiative recombination efficiency, the Al component needs to be reduced, and on the other hand, to obtain the deep ultraviolet band, the Al component needs to be increased. This is the inherent contradiction of AlGaN-based deep ultraviolet LEDs. AlGaN-based light-emitting diodes with a stepped quantum well structure can effectively solve this problem.

[0004] Therefore, how to provide a light emitting diode with a stepped quantum well structure that can improve the electron and hole wave function overlap rate and the radiation recombination efficiency is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of this, the present invention provides a light emitting diode with a stepped quantum well structure and a preparation method thereof. By growing a stepped quantum well active region, the problem that the AlGaN-based deep ultraviolet LED has a high Al component, has an extremely strong polarization electric field, and has a low overlap rate of electron and hole wave functions, low radiation recombination efficiency and low luminescence efficiency due to band bending and deformation is solved.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A light emitting diode with a stepped quantum well structure comprises: an N-type electrode, a P-type electrode, a substrate, and an N-type conductive layer, a quantum well active region, a P-type electron blocking layer and a P-type conductive layer sequentially stacked on the substrate;

[0008] Wherein, the N-type electrode is electrically connected to the N-type conductive layer; the P-type electrode is electrically connected to the P-type conductive layer;

[0009] The quantum well active region includes a quantum well layer and an Al 0.6 Ga 0.4 N quantum barrier layers; the quantum well layer is a step-type quantum well, and its thickness is 2nm.

[0010] It can be seen from the above technical solution that, compared with the prior art, the present invention, by setting a quantum well active region, will not cause an extremely strong polarization electric field, thereby improving the band bending caused by the polarization effect, and increasing the overlap rate of electron and hole wave functions, ultimately improving the radiation recombination efficiency and luminescence efficiency of the diode.

[0011] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the quantum well layer is a two-step quantum well; the quantum well layer comprises 1 nm thick Al 0.45 Ga 0.55 N layer and 1nm thick Al 0.55 Ga 0.45 N layers.

[0012] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the quantum well layer is a three-step quantum well; the quantum well layer comprises 0.5 nm thick Al 0.55 Ga 0.45 N layer, 1nm thick Al 0.45 Ga 0.55 N layer and 0.5nm thick Al 0.55 Ga 0.45 N layers.

[0013] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the quantum well layer is a five-step quantum well; the quantum well layer comprises 0.3 nm thick Al 0.55 Ga 0.45 N layer, 0.4nm thick Al 0.50 Ga 0.50 N layer, 0.6nm thick Al 0.45 Ga 0.55 N layer, 0.4nm thick Al 0.50 Ga 0.50 N layer and 0.3nm thick Al 0.55 Ga 0.45 N layers.

[0014] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the thickness of the quantum barrier layer is 10 nm.

[0015] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the N-type conductive layer is Si-doped N-type Al 0.6 Ga 0.4 N, and its thickness is 3 μm, and the doping concentration of the N-type conductive layer is 5×e +18 cm -3.

[0016] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the P-type electron blocking layer is Mg-doped P-type Al 0.65 Ga 0.35 N, and its thickness is 20nm; the doping concentration of the P-type electron blocking layer is 1×e +19 cm -3 .

[0017] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the substrate is a sapphire substrate.

[0018] Preferably, in the above-mentioned light-emitting diode with a stepped quantum well structure, the P-type conductive layer comprises a stacked arrangement of Mg-doped P-type Al 0.6 Ga 0.4 N layer and P-type GaN layer; the P-type Al 0.6 Ga 0.4 The thickness of the N layer is 20 nm, the thickness of the P-type GaN layer is 100 nm; the thickness of the P-type Al 0.6 Ga 0.4 The doping concentration of the N layer is 3×e +19 cm -3 ; The doping concentration of the P-type GaN layer is 5×e +19 cm -3 .

[0019] The present invention also discloses a method for preparing a light emitting diode with a stepped quantum well structure, comprising the following steps:

[0020] S1, selecting a substrate, and growing an N-type conductive layer stacked on the substrate under a hydrogen atmosphere at 1000-1200° C.;

[0021] S2, growing a quantum well active region stacked on the N-type conductive layer under a nitrogen atmosphere and a temperature of 800-1000° C.;

[0022] S3, growing a P-type electron blocking layer stacked on the quantum well active region under a nitrogen atmosphere at 1000-1200° C.;

[0023] S4. In a hydrogen atmosphere at 800-1000° C., growing a P-type conductive layer stacked on the P-type electron blocking layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 The accompanying drawing is a schematic diagram of the structure provided by the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, the embodiment of the present invention discloses a light emitting diode with an emission wavelength of 280nm and a stepped quantum well structure, comprising: an N-type electrode 1, a P-type electrode 2, a substrate 3, and an N-type conductive layer 4, a quantum well active region 5, a P-type electron blocking layer 6 and a P-type conductive layer 7 sequentially stacked on the substrate 3;

[0028] The N-type electrode 1 is electrically connected to the N-type conductive layer 4; the P-type electrode 2 is electrically connected to the P-type conductive layer 6;

[0029] The quantum well active region 5 includes a quantum well layer and an Al2O3 layer sequentially stacked on the N-type conductive layer 4. 0.6 Ga 0.4 N quantum barrier layers; the quantum well layer is a step-type quantum well, and its thickness is 2nm.

[0030] In one embodiment, n=2; the quantum well layer is a two-step quantum well; the quantum well layer includes 1 nm thick Al 0.45 Ga 0.55 N layer and 1nm thick Al 0.55 Ga 0.45 N layers.

[0031] In another embodiment, the quantum well layer is a three-step quantum well; the quantum well layer includes 0.5 nm thick Al 0.55 Ga 0.45 N layer, 1nm thick Al 0.45 Ga 0.55 N layer and 0.5nm thick Al 0.55 Ga 0.45 N layers.

[0032] In other embodiments, the quantum well layer is a five-step quantum well; the quantum well layer includes 0.3 nm thick Al 0.55 Ga 0.45 N layer, 0.4nm thick Al 0.50 Ga 0.50 N layer, 0.6nm thick Al 0.45 Ga 0.55 N layer, 0.4nm thick Al 0.50 Ga 0.50 N layer and 0.3nm thick Al 0.55 Ga 0.45 N layers.

[0033] The structural parameters of the conventional quantum well and the stepped quantum well in the above embodiment of the present invention are shown in Table 1.

[0034] Table 1

[0035]

[0036] The present invention provides a quantum well active region with a stepped quantum well, which will not cause an extremely strong polarization electric field, thereby improving the energy band bending caused by the polarization effect, and increasing the overlap rate of electron and hole wave functions, ultimately improving the radiation recombination efficiency and luminescence efficiency of the diode.

[0037] Specifically, the thickness of the quantum barrier layer is 10 nm.

[0038] The N-type conductive layer 4 is Si-doped N-type Al 0.6 Ga 0.4 N, and its thickness is 3 μm, and the doping concentration of the N-type conductive layer 4 is 5×e +18 cm -3 .

[0039] The P-type electron blocking layer 6 is a P-type Al doped with Mg. 0.65 Ga 0.35 N, and its thickness is 20nm; the doping concentration of the P-type electron blocking layer 6 is 1×e +19 cm -3 .

[0040] The substrate 3 is a sapphire substrate or a silicon carbide substrate.

[0041] The P-type conductive layer 7 includes a stacked arrangement of Mg-doped P-type Al 0.6 Ga 0.4 N layer 71 and P-type GaN layer 72; P-type Al 0.6 Ga 0.4 The thickness of the N layer is 20nm, the thickness of the P-type GaN layer is 100nm; the thickness of the P-type Al0.6 Ga 0.4 The doping concentration of the N layer is 3×e +19 cm -3 ; The doping concentration of the P-type GaN layer is 5×e +19 cm -3 .

[0042] The embodiment of the present invention also discloses a method for preparing a light emitting diode with a stepped quantum well structure, comprising the following steps:

[0043] S1. Select a substrate 3 and grow an N-type conductive layer 4 stacked on the substrate under a hydrogen atmosphere at 1000-1200°C; the N-type conductive layer 4 is a Si-doped N-type Al with a thickness of 3 μm. 0.6 Ga 0.4 N layer, where Si = 5×e +18 ;

[0044] S2, in a nitrogen atmosphere at a temperature of 800-1000°C, growing a quantum well active region 5 stacked on an N-type conductive layer 4; the quantum well active region 5 is composed of quantum well layers and quantum barrier layers grown alternately stacked, and the quantum well layer is Al 0.5 Ga 0.5 N, thickness is 2nm, quantum barrier layer is Al 0.6 Ga 0.4 N, thickness is 10nm.

[0045] S3, in a nitrogen atmosphere at 1000-1200° C., growing a P-type electron blocking layer 6 stacked on the quantum well active region 5; the P-type electron blocking layer 6 is a 20 nm thick, Mg-doped P-type Al 0.65 Ga 0.35 N, where Mg = 1 × e +19 cm -3 .

[0046] S4, in a hydrogen atmosphere at 800-1000° C., growing a P-type conductive layer 7 stacked on a P-type electron blocking layer 6; the electron blocking layer 6 comprises a 20 nm thick P-type Al 0.6 Ga 0.4 N layer and 100nm thick heavily doped P-type GaN layer; P-type Al 0.6 Ga 0.4 The doping concentration of the N layer is 3×e +19 cm -3 , the doping concentration of the P-type GaN layer is 5×e +19 cm -3 .

[0047] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0048] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A light emitting diode with a stepped quantum well structure, characterized in that: include: An N-type electrode (1), a P-type electrode (2), a substrate (3), and an N-type conductive layer (4), a quantum well active region (5), a P-type electron blocking layer (6), and a P-type conductive layer (7) sequentially stacked on the substrate (3); Wherein, the N-type electrode (1) is electrically connected to the N-type conductive layer (4); the P-type electrode (2) is electrically connected to the P-type conductive layer (7); The quantum well active region (5) comprises a quantum well layer and an Al2O3 layer sequentially stacked on the N-type conductive layer (4). 0.6 Ga 0.4 N quantum barrier layers; the quantum well layer is a step-type quantum well, and its thickness is 2nm; The quantum well layer is a five-step quantum well; the quantum well layer includes 0.3 nm thick Al 0.55 Ga 0.45 N layer, 0.4nm thick Al 0.50 Ga 0.50 N layer, 0.6nm thick Al 0.45 Ga 0.55 N layer, 0.4nm thick Al 0.50 Ga 0.50 N layer and 0.3nm thick Al 0.55 Ga 0.45 N layers; The N-type conductive layer (4) is Si-doped N-type Al 0.6 Ga 0.4 N, the P-type electron blocking layer (6) is Mg-doped P-type Al 0.65 Ga 0.35 N.

2. A light emitting diode with a stepped quantum well structure according to claim 1, characterized in that: The thickness of the quantum barrier layer is 10 nm.

3. A light emitting diode with a stepped quantum well structure according to claim 1, characterized in that: The thickness of the N-type conductive layer (4) is 3 μm, and the doping concentration of the N-type conductive layer (4) is 5×e +18 cm -3 .

4. A light emitting diode with a stepped quantum well structure according to claim 1, characterized in that: The thickness of the P-type electron blocking layer (6) is 20 nm; the doping concentration of the P-type electron blocking layer (6) is 1×e +19 cm -3 .

5. The light emitting diode with a stepped quantum well structure according to claim 1, characterized in that: The substrate (3) is a sapphire substrate.

6. A light emitting diode with a stepped quantum well structure according to claim 1, characterized in that: The P-type conductive layer (7) comprises a stacked arrangement of Mg-doped P-type Al 0.6 Ga 0.4 N layer (71) and P-type GaN layer (72); the P-type Al 0.6 Ga 0.4 The thickness of the N layer is 20 nm, the thickness of the P-type GaN layer is 100 nm; the thickness of the P-type Al 0.6 Ga 0.4 The doping concentration of the N layer is 3×e +19 cm -3 ; The doping concentration of the P-type GaN layer is 5×e +19 cm -3 .

7. A method for preparing a light emitting diode with a stepped quantum well structure as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1, selecting a substrate (3), and growing an N-type conductive layer (4) stacked on the substrate in a hydrogen atmosphere at 1000-1200° C.; S2, growing a quantum well active region (5) stacked on the N-type conductive layer (4) under a nitrogen atmosphere and a temperature of 800-1000° C.; S3, growing a P-type electron blocking layer (6) stacked on the quantum well active region (5) in a nitrogen atmosphere at 1000-1200° C.; S4. In a hydrogen atmosphere at 800-1000° C., growing a P-type conductive layer (7) stacked on the P-type electron blocking layer (6).

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