Full-spectrum chip epitaxial structure and growth method thereof

Abstract

The invention belongs to the technical field of LED chips, and discloses a full-spectrum chip epitaxial structure and a growth method thereof, and the epitaxial structure comprises a substrate, and a buffer layer, a U-GaN layer, an N-type GaN layer, a multispectral light-emitting quantum well group and a P-type GaN layer which are sequentially stacked on the substrate. The multispectral light-emitting quantum well group comprises a first spectral light-emitting quantum well layer, a second spectral light-emitting quantum well layer and a third spectral light-emitting quantum well layer which are sequentially distributed from bottom to top, and a modulation tuning well group is arranged between every two adjacent spectral light-emitting quantum well layers. According to the invention, the modulation tuning wells are inserted among different types of wells, and carrier distribution of different light-emitting wells is regulated and separated through strain and energy band engineering, so that crosstalk of different MQWs is avoided, and the luminous efficiency and spectral attenuation are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of LED chips, and in particular relates to a full-spectrum chip epitaxial structure and a growth method thereof. Background Art

[0002] With the widespread application of LED technology in high-end lighting, display, and biomedical fields, the market demand for full-spectrum LEDs is growing. Traditional white light LEDs mainly use blue light chips to excite phosphors, but they have problems such as spectral discontinuity, insufficient color rendering index (CRI), and limited color temperature adjustment range. The specific problems are as follows: (1) Spectral discontinuity: It is difficult to cover the entire ultraviolet, blue, green, and red light bands, resulting in poor color rendering; (2) Severe efficiency roll-off: The multi-quantum well (MQW) structure design is simple, carrier localization is insufficient, and efficiency decays rapidly under high current; (3) Difficulty in color temperature adjustment: The traditional structure cannot dynamically tune the luminous intensity of each band, making it difficult to achieve a wide color temperature range (such as 2700K-6500K); (4) Severe wavelength and brightness drift under variable current conditions: Under different current conditions, the luminous bands of traditional multi-band quantum wells drift and the efficiency affects each other. Summary of the Invention

[0003] In response to the deficiencies in the background technology, the present invention provides a full-spectrum chip epitaxial structure and a growth method thereof, inserts a modulated tuning well between different types of wells, and separates the carrier distribution of different light-emitting wells through strain and band engineering regulation, thereby avoiding crosstalk between different MQWs and significantly reducing light efficiency and spectral attenuation.

[0004] To achieve the above objectives, the technical solutions of the present invention are as follows: A full-spectrum chip epitaxial structure includes a substrate, and a buffer layer, a U-GaN layer, an N-type GaN layer, a multi-spectral light-emitting quantum well group, and a P-type GaN layer stacked in sequence on the substrate. The multi-spectral light-emitting quantum well group includes a first spectrum light-emitting quantum well layer, a second spectrum light-emitting quantum well layer, and a third spectrum light-emitting quantum well layer distributed in sequence from bottom to top, and a modulation tuning well group is provided between every two adjacent spectrum light-emitting quantum well layers.

[0005] Preferably, the modulation tuning well group includes n tuning well layers, and the i-th tuning well layer is In mi Ga （1-mi） N, i=1, 2, ..., n; n≥2; and satisfies m1≤ m2 ≤ ... ≤ mn; wherein the tuning well layer with i=1 is adjacent to one side of the N-type GaN layer, and the tuning well layer with i=n is adjacent to one side of the P-type GaN layer.

[0006] Preferably, the well layer of the spectrum luminescence quantum well group of the modulation tuning well group adjacent to the N-type GaN layer is In a1 Ga（1-a1） N, the well layer of the spectral luminescence quantum well group adjacent to the P-type GaN layer is In b1 Ga （1-b1） N, and satisfies a1>b1>mn.

[0007] A full-spectrum chip epitaxial structure growth method, comprising: A substrate is taken, and a buffer layer, a U-GaN layer, an N-type GaN layer, a multi-spectral light-emitting quantum well group, and a P-type GaN layer are sequentially deposited on the surface of the substrate.

[0008] Compared with the prior art, the present invention has the following beneficial effects: The present invention inserts a modulation tuning well group between different types of spectral luminescence quantum well layers, and separates the carrier distribution of different spectral luminescence quantum well groups through strain and band engineering regulation, thereby avoiding crosstalk between different MQWs and significantly reducing light efficiency and spectral attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0010] Figure 1 This is a schematic diagram of the epitaxial structure of the full-spectrum chip of the present invention; Figure 2 Schematic diagram of the traditional full-spectrum quantum well energy band; Figure 3 Schematic diagram of the full spectrum quantum well energy band including the modulation tuning well group of the present invention; Figure 4 A schematic flow chart of an epitaxial structure growth method according to an embodiment of the present invention; In the figure: 1. substrate, 2. buffer layer, 3. U-GaN layer, 4. N-type GaN layer, 5. multi-spectral light-emitting quantum well group, 501. first spectrum light-emitting quantum well layer, 502. second spectrum light-emitting quantum well layer, 503. third spectrum light-emitting quantum well layer, 504. modulation tuning well group, 6. P-type GaN layer. DETAILED DESCRIPTION

[0011] The following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0012] In this disclosure, unless otherwise indicated, directional terms such as "upper" and "lower" are generally defined in relation to the drawing planes of the accompanying drawings, and "inner" and "outer" refer to the inside and outside of the relevant components. Furthermore, the terms "first" and "second" are used solely for purposes of distinction and are not to be construed as indicating or implying relative importance.

[0013] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified or limited, the terms "disposed" and "connected" should be understood in a broad sense. For example, they may refer to a fixed connection, a detachable connection, or an integral connection. They may be directly connected or indirectly connected through an intermediate medium, or they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on specific circumstances.

[0014] like Figure 1 As shown, the present invention provides a full-spectrum chip epitaxial structure, including a substrate 1, and a buffer layer 2, a U-GaN layer 3, an N-type GaN layer 4, a multi-spectral light-emitting quantum well group 5, and a P-type GaN layer 6 stacked on the substrate in sequence.

[0015] The multi-spectral luminescence quantum well group includes a first spectral luminescence quantum well layer 501, a second spectral luminescence quantum well layer 502, and a third spectral luminescence quantum well layer 503, which are distributed in sequence from bottom to top. A modulation tuning well group 504 is provided between each adjacent two spectral luminescence quantum well layers. The modulation tuning well group is distributed between the wells of different systems. The carrier distribution of different luminescence wells is separated by strain and band engineering regulation, avoiding crosstalk between different spectral luminescence quantum well layers, and significantly reducing light efficiency and spectral attenuation. The structure of the first spectral luminescence quantum well layer, the second spectral luminescence quantum well layer, and the third spectral luminescence quantum well layer is the same as the quantum well structure corresponding to the traditional fixed light wavelength. It can be a single quantum well or a multiple quantum well. This structure is not the core protection content of this patent and will not be repeated here.

[0016] The modulation tuning well group 504 of the present invention does not participate in luminescence and will not interfere with the components of the spectrum, but can modulate the luminescence intensity of the corresponding spectrum luminescent quantum well layer. After the modulation tuning well group is introduced into each required spectrum luminescent well, the carrier distribution crosstalk of each system well (spectral luminescent quantum well layer) is effectively separated, so that the luminescent spectrum is stable and adaptable to the wide-variable current, effectively reducing the problem of power consumption loss in the full required band. The adjustment tuning well group plays a strain buffer role, effectively transitioning the polarization effect caused by different In incorporation amounts in different luminescent wells, causing band distortion and resulting in spectral drift of the fixed band luminescent well. The modulation tuning well group can also effectively increase the expansion effect of carriers in the active layer and provide a three-dimensional space for electron transition, thereby improving the uniformity of carrier distribution in each band spectral luminescent well under different current drive.

[0017] like Figure 3 As shown, the modulation tuning well group includes n tuning well layers, and the material chemical formula of the i-th tuning well layer is In mi Ga （1-mi）N, i=1,2,…,n; n≥2; and satisfies m1≤ m2 ≤ … ≤ mn; wherein, the tuning well layer of i=1 is adjacent to the N-type GaN layer side, the tuning well layer of i=n is adjacent to the P-type GaN layer side, and the well layer material chemical formula of the spectrum luminescence quantum well group of the modulation tuning well group adjacent to the N-type GaN layer side is In a1 Ga （1-a1） N, the chemical formula of the well layer material of the spectral luminescence quantum well group adjacent to the P-type GaN layer is In b1 Ga （1-b1） N, and satisfies a1>b1>mn.

[0018] The present invention utilizes modulation tuning wells in each main light-emitting band to improve the luminescence characteristics of the full-spectrum LED chip, and optimizes carrier transport and stable radiation recombination through band regulation and strain engineering. This is mainly reflected in the fact that the multi-spectral quantum well output light of the epitaxial layer structure is stable and adjustable. In addition, the wavelength drift under variable current conditions and the possible attenuation of a certain band are significantly reduced, thereby affecting the stability of the color gamut and the decline in the color rendering index. In addition, the introduction of modulation tuning wells reduces the difference in In content in different light-emitting wells, causing stress strain and polarization electric fields in adjacent system quantum wells, reducing the carrier confinement effect, causing the light-emitting well efficiency to decrease, the attenuation to be too fast, and the adaptive current range to be small, which brings flexibility to the chip structure design and limited application.

[0019] Combine Figure 2 and Figure 3 As shown, the full-spectrum chip epitaxial structure of the present invention improves the MOCVD in the PM full-cycle band, which is adjustable in time and the wavelength difference between the multi-spectral wells is stable. However, the conventional full-spectrum chip epitaxial structure has a spectrum deviation from the required band after MOCVD maintenance, and the spectrum band adjustment cannot be adjusted back in time and the deviation of each band varies. Compared with the conventional epitaxial structure with stacked light-emitting wells in each required band, the full-spectrum chip with a modulated tuning well structure of the present invention has a stable spectrum band and can adapt to a wider current range (15mA-90mA), so that the product has the following advantages: (1) high color rendering index: CRI>95, meeting the needs of high-end lighting; (2) high efficiency and low roll-off, the tuning well design balances carrier injection, and the efficiency roll-off is improved by more than 30%; (3) dynamic color temperature adjustment: the luminous intensity of each well is controlled by current density to achieve stepless color temperature tuning.

[0020] like Figure 4 As shown, the present invention also provides a full-spectrum chip epitaxial structure growth method, comprising: S1, take a substrate 1; S2, depositing a buffer layer 2, a U-GaN layer 3, an N-type GaN layer 4, a multi-spectral light-emitting quantum well group 5, and a P-type GaN layer 6 on the surface of the substrate in sequence.

[0021] The growth conditions of the buffer layer are: pressure 50-600 torr, temperature 700-900°C. The growth conditions of the U-GaN layer are: pressure 50-300 torr, temperature 1000-1160°C, and Ga and Si sources are introduced. The growth conditions of the N-type GaN layer are: pressure 100-300 torr, growth temperature 1050-1110°C, and Ga and Si sources are introduced. The light-emitting quantum well groups of each color spectrum are stacked in sequence after the growth of the N-type GaN layer. They grow non-alternatingly, and the wavelengths of each group tend to be shorter. Since the growth conditions of each color spectrum are not fixed, MQW is not subject to growth condition restrictions. It is the existing technology in this technical field. The modulation tuning well group is a shallow layer of the light-emitting well and is consistent with its growth conditions. The growth conditions of the P-type GaN layer are: pressure 100-600 torr, growth temperature 900-1050, and Ga and Mg sources are introduced.

[0022] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and it is intended that all changes that come within the meaning and range of equivalents of the claims be included therein.

Claims

1. A full-spectrum chip epitaxial structure, characterized by: It includes a substrate, and a buffer layer, a U-GaN layer, an N-type GaN layer, a multi-spectral light-emitting quantum well group, and a P-type GaN layer stacked in sequence on the substrate. The multi-spectral light-emitting quantum well group includes a first spectrum light-emitting quantum well layer, a second spectrum light-emitting quantum well layer, and a third spectrum light-emitting quantum well layer distributed in sequence from bottom to top, and a modulation tuning well group is provided between every two adjacent spectrum light-emitting quantum well layers.

2. The full-spectrum chip epitaxial structure according to claim 1, characterized in that: The modulation tuning well group includes n tuning well layers, and the i-th tuning well layer is In mi Ga （1-mi） N, i=1, 2, ..., n; n≥2; and satisfies m1≤ m2 ≤ ... ≤mn; wherein the tuning well layer with i=1 is adjacent to one side of the N-type GaN layer, and the tuning well layer with i=n is adjacent to one side of the P-type GaN layer.

3. The full-spectrum chip epitaxial structure according to claim 2, wherein: The well layer of the spectrum luminescence quantum well group of the modulation tuning well group adjacent to the N-type GaN layer is In a1 Ga （1-a1） N, the well layer of the spectral luminescence quantum well group adjacent to the P-type GaN layer is In b1 Ga （1-b1） N, and satisfies a1>b1>mn.

4. A method for growing a full-spectrum chip epitaxial structure according to any one of claims 1 to 3, characterized in that: include: A substrate is taken, and a buffer layer, a U-GaN layer, an N-type GaN layer, a multi-spectral light-emitting quantum well group, and a P-type GaN layer are sequentially deposited on the surface of the substrate.

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