Green light-emitting diode (LED) chip based on N-type GaN layer embedded distributed bragg reflector (DBR) structure

Abstract

The utility model belongs to the technical field of LED chips, and discloses a green light LED chip based on an N-type GaN layer embedded DBR structure, which comprises a substrate, and a first buffer layer, a first non-doped GaN layer, a green light MQW layer, a second non-doped GaN layer, an N-type GaN layer, a DBR layer, a second buffer layer, a third non-doped GaN layer, a blue light MQW layer, an electron blocking layer and a P-type GaN layer which are sequentially deposited on the substrate, a P electrode is arranged on the P-type GaN layer, and the DBR layer is formed by periodically and alternately laminating two dielectric materials with different refractive indexes. According to the utility model, the DBR layer is embedded between the N-type GaN layer and the blue light quantum well, downward photons are directly reflected, the light extraction efficiency is improved, the photon reflection path is shortened, the absorption loss is reduced, a low-stress growth template is provided for the blue light quantum well, the dislocation density is reduced, and the growth quality of the blue light quantum well is improved.

Description

Technical Field

[0001] This utility model belongs to the field of LED chip technology, specifically relating to a green LED chip based on an N-type GaN layer embedded DBR structure. Background Technology

[0002] Traditional green LEDs involve directly growing blue quantum wells (QWells) after a 3D-grown fill layer on a sapphire substrate. However, this process suffers from high dislocation density due to lattice mismatch, limiting the internal quantum efficiency (IQE). Existing distributed beamforming (DBRs) are mostly located at the substrate interface or on the back of the chip, which not only fails to optimize the growth interface of the blue quantum well but also results in long light reflection paths leading to absorption losses. Therefore, there is an urgent need to optimize the location and structure of the DBR in green LED chips to reduce dislocations in the blue quantum well and improve its light extraction efficiency. Utility Model Content

[0003] This invention addresses the shortcomings of the prior art by providing a green LED chip based on an N-type GaN layer embedded DBR structure. By optimizing the position and structure of the DBR, dislocations in the blue quantum well growth are reduced, thereby improving the light extraction efficiency of the blue quantum well.

[0004] To achieve the above objectives, the technical solution of this utility model is as follows:

[0005] A green LED chip based on an N-type GaN layer embedded DBR structure includes a substrate and a first buffer layer, a first undoped GaN layer, a green MQW layer, a second undoped GaN layer, an N-type GaN layer, a DBR layer, a second buffer layer, a third undoped GaN layer, a blue MQW layer, an electron blocking layer, and a P-type GaN layer sequentially deposited on the substrate. The N-type GaN layer has an N electrode, the P-type GaN layer has a P electrode, and the DBR layer is formed by periodically alternating layers of two dielectric materials with different refractive indices.

[0006] Preferably, the thicknesses of the first undoped GaN layer, the third undoped GaN layer, and the second undoped GaN layer decrease sequentially.

[0007] Preferably, the number of alternating stacking periods of the DBR layer is 5-30, and the single-layer optical thickness is λ / (4n), where λ is 380-480nm and n is the refractive index of the dielectric material.

[0008] Preferably, the two media materials are Al2O3 and SiO2, or Si3N4 and SiO2.

[0009] Preferably, the DBR layer forms a periodic patterned structure on the N-type GaN layer.

[0010] Preferably, the graphic structure is a pyramidal structure, a conical structure, or a frustum structure, and the base of the graphic structure is a polygon or a circle.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0012] (1) This utility model embeds the DBR layer between the N-type GaN layer and the blue quantum well, directly reflecting downward photons, improving the light extraction efficiency, shortening the photon reflection path, reducing absorption loss, and the patterned structure can also more effectively change the direction of light propagation. At the same time, it provides a low-stress growth template for the blue quantum well, which reduces the dislocation density and improves the growth quality of the blue quantum well.

[0013] (2) The DBR layer of this utility model is selected from Al2O3 / SiO2 or Si3N4 / SiO2 combination, with a refractive index difference Δn≥0.2 and a thermal expansion coefficient matching GaN, which solves the stress problem inside the epitaxial layer and avoids high temperature cracking. Attached Figure Description

[0014] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0015] Figure 1 This is a schematic diagram of the chip structure of this utility model;

[0016] In the figure: 1. Substrate, 2. First buffer layer, 3. First undoped GaN layer, 4. Green MQW layer, 5. Second undoped GaN layer, 6. N-type GaN layer, 7. DBR layer, 8. Second buffer layer, 9. Third undoped GaN layer, 10. Blue MQW layer, 11. Electron blocking layer, 12. P-type GaN layer, 13. N electrode, 14. P electrode. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0018] In the description of this utility model, it should be understood that the terms "middle", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] like Figure 1 As shown, a green LED chip based on an N-type GaN layer embedded DBR structure includes a substrate 1, and a first buffer layer 2, a first undoped GaN layer 3, a green MQW layer 4, a second undoped GaN layer 5, an N-type GaN layer 6, a DBR layer 7, a second buffer layer 8, a third undoped GaN layer 9, a blue MQW layer 10, an electron blocking layer 11, and a P-type GaN layer 12 sequentially deposited on the substrate. The thicknesses of the first undoped GaN layer, the third undoped GaN layer, and the second undoped GaN layer are shown. The layers decrease in size sequentially. An N-type GaN layer has an N-electrode 13, and a P-type GaN layer has a P-electrode 14. The DBR layer is formed by periodically alternating layers of two dielectric materials with different refractive indices. The number of alternating layers in the DBR layer is 5-30, and the single-layer optical thickness is λ / (4n), where λ is 380-480 nm and n is the refractive index of the dielectric material. The two dielectric materials are Al2O3 and SiO2, or Si3N4 and SiO2. In this embodiment, Al2O3 and SiO2 are selected. An embedded DBR is formed using materials with different refractive indices and minimal lattice mismatch with GaN. The DBR layer forms a periodic patterned structure on the N-type GaN layer. The patterned structure is a pyramidal structure, a conical structure, or a frustum structure. The base of the patterned structure is polygonal or circular; in this embodiment, it is a conical structure with a circular base. Patterned DBRs include micron-level basic patterns (periods 1-10μm) and nano-level surface structures (periods 100-500nm). Patterning increases the effective path for DBR-reflected photons and improves the light output efficiency of specific optical paths.

[0020] The method for manufacturing the green LED chip of this utility model includes the following steps:

[0021] S1, Green quantum well fabrication: Low-temperature buffer layer / 3D growth layer / 2D filler layer / green quantum well / N-type GaN are grown on patterned sapphire or composite substrates such as Al2O3&SiO2.

[0022] S2, DBR layer embedding: Al2O3 / SiO2 or SiO2 / Si3N4 is deposited on the surface of the above NGaN layer by ALD (atomic deposition) or PECVD, with 5-30 pairs of layers and a single layer thickness of λ / (4n) (λ is the target light wavelength). The DBR layer is patterned (photolithography + dry etching to form a micron-scale array structure).

[0023] S3, Blue quantum well fabrication: A low-temperature buffer layer / 3D growth layer / 2D filler layer is regrown on the above-mentioned DBR embedding layer, and a blue quantum well is grown on this basis, followed by the addition of a P-type electron blocking layer and a P-type GaN.

[0024] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model.

Claims

1. A green LED chip based on an N-type GaN layer embedded DBR structure, characterized in that: The device includes a substrate, and a first buffer layer, a first undoped GaN layer, a green MQW layer, a second undoped GaN layer, an N-type GaN layer, a DBR layer, a second buffer layer, a third undoped GaN layer, a blue MQW layer, an electron blocking layer, and a P-type GaN layer sequentially deposited on the substrate. The N-type GaN layer has an N electrode, the P-type GaN layer has a P electrode, and the DBR layer is formed by periodically alternating layers of two dielectric materials with different refractive indices.

2. The green LED chip based on an N-type GaN layer embedded DBR structure as described in claim 1, characterized in that: The thicknesses of the first undoped GaN layer, the third undoped GaN layer, and the second undoped GaN layer decrease sequentially.

3. The green LED chip based on an N-type GaN layer embedded DBR structure as described in claim 1, characterized in that: The number of alternating stacking periods of the DBR layer is 5-30, and the optical thickness of a single layer is λ / (4n), where λ is 380-480nm and n is the refractive index of the dielectric material.

4. The green LED chip based on an N-type GaN layer embedded DBR structure as described in claim 1, characterized in that: The two media materials are Al2O3 and SiO2, or Si3N4 and SiO2.

5. The green LED chip based on an N-type GaN layer embedded DBR structure as described in claim 1, characterized in that: The DBR layer forms a periodic pattern structure on the N-type GaN layer.

6. The green LED chip based on an N-type GaN layer embedded DBR structure as described in claim 5, characterized in that: The graphic structure is a pyramidal structure, a conical structure, or a frustum structure, and the base of the graphic structure is a polygon or a circle.

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