A full-spectrum chip epitaxial structure and a growth method thereof

Abstract

The application belongs to the technical field of LED chips, and discloses a full-spectrum chip epitaxial structure and a growth method thereof. The epitaxial structure comprises a substrate, a buffer layer, a U-GaN layer, an N-type GaN layer, a multi-spectrum light-emitting quantum well group, and a P-type GaN layer which are sequentially stacked on the substrate. The multi-spectrum light-emitting quantum well group comprises 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 which are sequentially distributed from bottom to top. A modulation tuning well group is arranged between each two adjacent spectrum light-emitting quantum well layers. The modulation tuning well is inserted between different types of wells, the carrier distribution of different light-emitting wells is controlled through strain and energy band engineering, the crosstalk of different MQWs is avoided, and the light efficiency and spectrum attenuation are greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of LED chip technology, specifically relating to a full-spectrum chip epitaxial structure and its growth method. Background Technology

[0002] With the widespread application of LED technology in high-end lighting, display and biomedicine, the market demand for full-spectrum LEDs is growing. Traditional white LEDs mainly use blue light chips to excite phosphors, but there are problems such as discontinuous spectrum, insufficient color rendering index (CRI) and limited color temperature adjustment range. The specific situations are as follows: (1) Discontinuous spectrum: It is difficult to cover the full band of ultraviolet, blue light, green light and red light, resulting in poor color rendering; (2) Severe efficiency roll-off: The multi-quantum well (MQW) structure design is simple, the carrier localization is insufficient, and the efficiency decays quickly under high current; (3) Difficult color temperature adjustment: Traditional structures 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 each quantum well drift and the efficiency affects each other. Summary of the Invention

[0003] To address the shortcomings of the prior art, this invention provides a full-spectrum chip epitaxial structure and its growth method. By inserting modulation and tuning wells between different types of wells, and controlling the carrier distribution of different light-emitting wells through strain and bandgap engineering, crosstalk between different MQWs is avoided, and the luminous efficiency and spectral attenuation are significantly reduced.

[0004] To achieve the above objectives, the technical solution of this invention is 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 multispectral light-emitting quantum well group, and a P-type GaN layer sequentially stacked on the substrate. The multispectral light-emitting quantum well group includes 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 distributed from bottom to top. A modulation and tuning well group is provided between each two adjacent spectral 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 satisfy m1≤ m2 ≤ … ≤ mn; where the tuned well layer with i=1 is adjacent to the side of the N-type GaN layer, and the tuned well layer with i=n is adjacent to the side of the P-type GaN layer.

[0006] Preferably, the well layer of the spectrally luminescent quantum well group adjacent to the N-type GaN layer in the modulation and tuning well group is In. a1 Ga（1-a1） N, the well layer of the spectrally luminescent quantum well group adjacent to the p-type GaN layer is In. b1 Ga （1-b1） N, and satisfying a1>b1>mn.

[0007] A method for growing a full-spectrum chip epitaxial structure, comprising: Take a substrate and deposit a buffer layer, a U-GaN layer, an N-type GaN layer, a multispectral light-emitting quantum well array, and a P-type GaN layer sequentially on the surface of the substrate.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention avoids crosstalk between different MQWs by inserting modulation and tuning well groups between different types of spectral luminescent quantum well layers, and by controlling the carrier distribution of different spectral luminescent quantum well groups through strain and band engineering, thereby significantly reducing luminous efficiency and spectral attenuation. Attached Figure Description

[0009] Other features, objects, and advantages of the 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 full-spectrum chip epitaxial structure of the present invention; Figure 2 A schematic diagram of the band structure of a conventional full-spectrum quantum trap; Figure 3 This is a schematic diagram of the full-spectrum quantum well energy band structure containing the modulation and tuning well group of the present invention; Figure 4 This is a schematic diagram of an epitaxial structure growth method according to one embodiment of the present invention; In the figure: 1. Substrate, 2. Buffer layer, 3. U-GaN layer, 4. N-type GaN layer, 5. Multispectral 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 and tuning well group, 6. P-type GaN layer. Detailed Implementation

[0011] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0012] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" are generally defined by the orientation of the accompanying drawings, and "inner" and "outer" refer to the inner and outer parts of the relevant components. Furthermore, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0013] In the description of this disclosure, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can be a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the 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 multispectral light-emitting quantum well group 5, and a P-type GaN layer 6 sequentially stacked on the substrate.

[0015] The multispectral luminescent quantum well array comprises, from bottom to top, a first spectral luminescent quantum well layer 501, a second spectral luminescent quantum well layer 502, and a third spectral luminescent quantum well layer 503. A modulation and tuning well group 504 is provided between each pair of adjacent spectral luminescent quantum well layers. The modulation and tuning well groups are distributed between different quantum wells, and the carrier distribution of different luminescent quantum wells is separated by strain and bandgap engineering to avoid crosstalk between different spectral luminescent quantum well layers, significantly reducing luminous efficiency and spectral attenuation. The structures of the first, second, and third spectral luminescent quantum well layers are the same as those of traditional fixed-wavelength quantum well structures, and can be single or multiple quantum wells. This structure is not the core protected content of this patent and will not be described further here.

[0016] The modulation and tuning well group 504 of this invention does not participate in light emission and does not interfere with the composition of the spectrum, but it can modulate the light emission intensity of its corresponding spectral light emission quantum well layer. After introducing the modulation and tuning well group into each desired spectral light emission well, it effectively separates the carrier distribution crosstalk of each system well (spectral light emission quantum well layer), making its light emission spectrum stable and adaptable to wide-range current, effectively reducing the problem of the effect of one increasing while the other decreases across the entire desired wavelength band. Adjusting the tuning well group acts as a strain buffer, effectively transitioning the polarization effect caused by different light emission wells due to different In incorporation amounts, which causes band distortion leading to spectral drift of the light emission well in a fixed wavelength band. The modulation and tuning well group can also effectively increase the carrier expansion effect in the active layer and provide three-dimensional space for electron transitions, improving the uniformity of carrier distribution in each spectral light emission well under different current driving conditions.

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

[0018] This invention utilizes modulation and tuning wells in each main emission band to improve the luminescence characteristics of a full-spectrum LED chip. By optimizing carrier transport and stable radiative recombination through bandgap modulation and strain engineering, it is mainly reflected in the stable and tunable output light from the multispectral quantum wells in the epitaxial layer structure. In addition, it significantly reduces wavelength drift and potential attenuation in a certain band under varying current conditions, which in turn affects the stability of the color gamut and the decrease in the color rendering index. Furthermore, the introduction of modulation and tuning wells reduces the stress, strain, and polarization electric field generated in adjacent quantum wells due to the different In content in different light-emitting wells, reducing the carrier confinement effect, causing a decrease in light-emitting well efficiency, excessive attenuation, and a small adaptable current range. This results in limited chip structure design flexibility and application limitations.

[0019] Combination Figure 2 and Figure 3 As shown, the full-spectrum chip epitaxial structure of the present invention improves the timely adjustability of MOCVD in the full-cycle band of PM and the stability of wavelength difference between multiple spectral wells. In contrast, the traditional full-spectrum chip epitaxial structure exhibits spectral shift in the required band after MOCVD maintenance, and the spectral band adjustment cannot be timely corrected, with varying degrees of shift in each band. Compared to the traditional epitaxial structure with stacked light-emitting wells for each required band, the full-spectrum chip of the present invention with modulation and tuning well structure has stable spectral bands and can adapt to a wider current range (15mA-90mA), giving the product 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, improving efficiency roll-off by more than 30%; (3) Dynamic color temperature adjustment: the luminous intensity of each well is controlled by the current density, achieving stepless color temperature tuning.

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

[0021] The growth conditions for the buffer layer are: pressure 50-600 torr, temperature 700-900℃. The growth conditions for the U-GaN layer are: pressure 50-300 torr, temperature 1000-1160℃, with Ga and Si sources introduced. The growth conditions for the N-type GaN layer are: pressure 100-300 torr, growth temperature 1050-1110℃, with Ga and Si sources introduced. The quantum well groups for each color spectrum are stacked sequentially after the N-type GaN layers are grown, without alternation, and the wavelengths of each group tend towards shorter wavelengths. Since the growth conditions for each color spectrum are not fixed, MQW does not have growth condition restrictions and is existing technology in this field. The modulation and tuning well group is a shallow layer of the luminescent well and its growth conditions are consistent with those of the MQW. The growth conditions for the P-type GaN layer are: pressure 100-600 torr, growth temperature 900-1050℃, with Ga and Mg sources introduced.

[0022] The foregoing has shown and described the basic principles, main features, and 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 invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A full-spectrum chip epitaxial structure, characterized in that: It includes 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 stacked sequentially on the substrate. The multispectral light-emitting quantum well group includes 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 distributed sequentially from bottom to top. A modulation and tuning well group is provided between each two adjacent spectral light-emitting quantum well layers. The modulation and tuning well group includes n tuning well layers, where the i-th tuning well layer is In. mi Ga （1-mi） N, i=1,2,…,n; n≥2; and satisfy m1≤ m2 ≤ … ≤ mn; where the tuned well layer with i=1 is adjacent to the side of the N-type GaN layer, and the tuned well layer with i=n is adjacent to the side of the P-type GaN layer. The well layer of the spectrally luminescent quantum well group adjacent to the N-type GaN layer in the modulation and tuning well group is In. a1 Ga （1-a1） N, the well layer of the spectrally luminescent quantum well group adjacent to the p-type GaN layer is In. b1 Ga （1-b1） N, and satisfying a1>b1>mn.

2. The method for growing a full-spectrum chip epitaxial structure as described in claim 1, characterized in that, include: Take a substrate and deposit a buffer layer, a U-GaN layer, an N-type GaN layer, a multispectral light-emitting quantum well array, and a P-type GaN layer sequentially on the surface of the substrate.

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