Dual-band light emitting diode and manufacturing method thereof

Abstract

The invention provides a dual-band light emitting diode and a manufacturing method thereof. The dual-band light emitting diode comprises a first epitaxial composite layer, a second epitaxial composite layer and a transparent conductive layer. Wherein the first epitaxial composite layer is provided with a first light-emitting layer of a first wave band, the second epitaxial composite layer is provided with a second light-emitting layer of a second wave band, and the first wave band is not smaller than the second wave band. The transparent conductive layer is sandwiched between the first epitaxial composite layer and the second epitaxial composite layer, and the first epitaxial composite layer is arranged on the second epitaxial composite layer.

Description

Technical Field

[0001] This invention relates to a dual-band light-emitting diode and its manufacturing method, and particularly to a dual-band short-wave infrared light-emitting diode and its manufacturing method. Background Technology

[0002] Light-emitting diodes (LEDs) have advantages such as high brightness, small size, low power consumption, and long lifespan, and are widely used in lighting and display products. In particular, LEDs have recently begun to be used in wearable devices. For example, LEDs are used in wearable devices for non-invasive blood glucose monitoring, avoiding the discomfort of long-term invasive blood glucose monitoring for users.

[0003] Taking blood glucose detection as an example, several LED chips belonging to the short-wavelength infrared (SWIR) band have been integrated into blood glucose detection modules. These include LED chips in the 1065 nm, 1350 nm, and 1450 nm bands. In particular, to improve measurement accuracy, blood glucose detection modules have begun to incorporate LED chips of two or more wavelengths within a single module. By using LEDs of different wavelengths, the different absorption characteristics of skin and blood for various wavelengths of light are addressed, thereby enhancing detection sensitivity.

[0004] Common multi-band blood glucose monitoring modules often combine 1065nm LED chips with 1350nm LED chips, or vice versa. However, 1065nm LEDs can only be epitaxially grown on gallium arsenide (GaAs) substrates. On the other hand, 1350nm and 1450nm LEDs require indium phosphide (InP) substrates for epitaxial growth. Therefore, LED packaging in multi-band blood glucose monitoring modules needs to integrate at least two different wavelengths, thus increasing packaging space to accommodate more LEDs. In light of this, the industry urgently needs an innovative LED structure and manufacturing method to meet the requirements of wearable devices that are both thin and accurate. Summary of the Invention

[0005] The main objective of this invention is to provide a high-brightness dual-band light-emitting diode and its manufacturing method, which can simultaneously provide short-wave infrared light in two bands within a single light-emitting diode structure, thereby reducing the package size of the light-emitting diode and meeting the requirements of thin and light-weight wearable devices for accurate detection.

[0006] To achieve the above objectives, the present invention provides a dual-band light-emitting diode (LED), comprising a first epitaxial composite layer, a second epitaxial composite layer, and a transparent conductive layer. The first epitaxial composite layer has a first light-emitting layer with a first wavelength band, and the second epitaxial composite layer has a second light-emitting layer with a second wavelength band, wherein the first wavelength band is not less than the second wavelength band. The transparent conductive layer is sandwiched between the first and second epitaxial composite layers, and the first epitaxial composite layer is disposed on top of the second epitaxial composite layer.

[0007] In one embodiment of the dual-band light-emitting diode of the present invention, the dual-band light-emitting diode further includes a P-type electrode disposed on a transparent conductive layer and electrically connected to the transparent conductive layer.

[0008] In one embodiment of the dual-band light-emitting diode of the present invention, the dual-band light-emitting diode further includes a first N-type electrode and a second N-type electrode, wherein the first N-type electrode is disposed on a first epitaxial composite layer and electrically connected to the first light-emitting layer, and the second N-type electrode is disposed on a second epitaxial composite layer and electrically connected to the second light-emitting layer.

[0009] In one embodiment of the dual-band light-emitting diode of the present invention, the first epitaxial composite layer further includes an N-type indium phosphide epitaxial layer and a P-type indium phosphide epitaxial layer, with the first light-emitting layer sandwiched between the N-type indium phosphide epitaxial layer and the P-type indium phosphide epitaxial layer.

[0010] In one embodiment of the dual-band light-emitting diode of the present invention, the first epitaxial composite layer further includes a P-type zinc-doped indium gallium arsenide phosphide epitaxial layer, which is sandwiched between the P-type indium phosphide epitaxial layer and the transparent conductive layer.

[0011] In one embodiment of the dual-band light-emitting diode of the present invention, the second epitaxial composite layer further includes an N-type aluminum gallium arsenide epitaxial layer and a P-type aluminum gallium arsenide epitaxial layer, with the second light-emitting layer sandwiched between the N-type aluminum gallium arsenide epitaxial layer and the P-type aluminum gallium arsenide epitaxial layer.

[0012] In one embodiment of the dual-band light-emitting diode of the present invention, the second epitaxial composite layer further includes a P-type carbon-doped gallium arsenide epitaxial layer, which is sandwiched between the P-type aluminum gallium arsenide epitaxial layer and the transparent conductive layer.

[0013] In one embodiment of the dual-band light-emitting diode of the present invention, the first band is 1100-2000 nanometers (nm) and the second band is 1000-1100 nanometers (nm).

[0014] In one embodiment of the dual-band light-emitting diode of the present invention, the thickness of the transparent conductive layer is

[0015] To achieve the above objectives, the present invention provides a method for manufacturing a dual-band light-emitting diode, comprising the following steps: First, a first epitaxial composite layer is formed on a first epitaxial growth substrate, the first epitaxial composite layer having a first light-emitting layer with a first wavelength band. Second, a first transparent conductive layer is formed on the first epitaxial composite layer. A second epitaxial composite layer is formed on a second epitaxial growth substrate, the second epitaxial composite layer having a second light-emitting layer with a second wavelength band, wherein the first wavelength band is not less than the second wavelength band. Next, a second transparent conductive layer is formed on the second epitaxial composite layer. Finally, the first transparent conductive layer and the second transparent conductive layer are bonded together, such that the first transparent conductive layer and the second transparent conductive layer are sandwiched between the first epitaxial composite layer and the second epitaxial composite layer, and the first epitaxial composite layer is disposed on the second epitaxial composite layer.

[0016] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, the method further includes removing the first epitaxial growth substrate and then performing a high-altitude etching on the first epitaxial composite layer to expose a portion of the first transparent conductive layer.

[0017] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, a P-type electrode is provided, disposed on an exposed first transparent conductive layer, and electrically connected to the first transparent conductive layer and the second transparent conductive layer.

[0018] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, a first N-type electrode is provided, disposed on the first epitaxial composite layer and electrically connected to the first light-emitting layer.

[0019] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, a step of thinning the second epitaxial growth substrate is further included.

[0020] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, a second N-type electrode is provided, disposed on a thinned second epitaxial growth substrate and electrically connected to the second light-emitting layer.

[0021] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, the step of providing a first epitaxial composite layer formed on a first epitaxial growth substrate is to sequentially provide an N-type indium phosphide epitaxial layer, a first light-emitting layer and a P-type indium phosphide epitaxial layer on an indium phosphide substrate.

[0022] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, the step of providing a second epitaxial composite layer formed on a second epitaxial growth substrate is to sequentially provide an N-type aluminum gallium arsenide epitaxial layer, a second light-emitting layer and a P-type aluminum gallium arsenide epitaxial layer on a gallium arsenide substrate.

[0023] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, the first band is 1100-2000 nanometers (nm) and the second band is 1000-1100 nanometers (nm).

[0024] In one embodiment of the dual-band light-emitting diode manufacturing method of the present invention, the total thickness after bonding the first transparent conductive layer and the second transparent conductive layer is:

[0025] Other objects of the present invention, as well as the technical means and implementation methods of the present invention, will be understood by those skilled in the art upon referring to the accompanying drawings and the embodiments described below. Attached Figure Description

[0026] Figures 1A to 1C This diagram shows a schematic of manufacturing a light-emitting diode structure having a first band in one embodiment of the present invention;

[0027] Figures 2A to 2B This diagram shows a schematic of manufacturing a light-emitting diode structure having a second band in one embodiment of the present invention;

[0028] Figures 3A to 3G This diagram shows a schematic of manufacturing a dual-band light-emitting diode according to an embodiment of the present invention;

[0029] Figure 4 This is a top view schematic diagram of a dual-band light-emitting diode according to an embodiment of the present invention; and

[0030] Figure 5 This is a schematic diagram of the manufacturing process steps of a dual-band light-emitting diode in one embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 10 First epitaxial growth substrate

[0033] 11 Buffer Layer

[0034] 12 N-type ohmic contact layer

[0035] 13 N-type indium phosphide epitaxial layer

[0036] 14 First Light-Emitting Layer

[0037] 15 P-type indium phosphide epitaxial layer

[0038] 16 P-type zinc-doped indium gallium arsenide phosphide epitaxial layer

[0039] 17 Metal Stacks

[0040] 18 First transparent conductive layer

[0041] 20 Second epitaxial growth substrate

[0042] 21 N-type gallium arsenide layer

[0043] 22 N-type aluminum gallium arsenide epitaxial layer

[0044] 23 Second light-emitting layer

[0045] 24 P-type aluminum gallium arsenide epitaxial layer

[0046] 25 P-type carbon-doped gallium arsenide epitaxial layer

[0047] 28 Second transparent conductive layer

[0048] 31 P-type electrode

[0049] 32 First N-type electrode

[0050] 33 Second N-type electrode. Detailed Implementation

[0051] The following embodiments will explain the content of this invention. These embodiments are not intended to limit the implementation of this invention to any specific environment, application, or special method described in the embodiments. Therefore, the descriptions of the embodiments are merely illustrative of the invention and not intended to limit it. It should be noted that in the following embodiments and accompanying drawings, elements not directly related to this invention have been omitted and are not shown, and the dimensional relationships between the elements in the drawings are for ease of understanding only and are not intended to limit the actual scale.

[0052] This invention discloses a dual-band light-emitting diode and its manufacturing method. The purpose is to house two independently operable light-emitting diodes within the same package, providing light in different wavelength ranges individually or jointly for various applications in subsequent modules. Therefore, this invention will specifically illustrate how to integrate two independent light-emitting diodes into a single package using the following embodiments.

[0053] First, prepare a light-emitting diode structure with a first wavelength range, where the first wavelength range can be, for example, but is not limited to, 1100–2000 nanometers (nm). See also... Figure 1AThe image shows a buffer layer 11 and an N-type ohmic contact layer 12 epitaxially grown on a first epitaxial growth substrate 10 using metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) techniques. Specifically, the first epitaxial growth substrate 10 is an indium phosphide (InP) substrate, but is not limited to this. Furthermore, the buffer layer 11 is an N-type indium phosphide (InP) epitaxial layer used to adjust the lattice matching between the epitaxial growth substrate and the epitaxial composite layer during subsequent epitaxial composite layer growth, reducing stress caused by lattice mismatch in subsequent epitaxial processes, thereby improving the film quality of subsequent epitaxial layers.

[0054] Secondly, the N-type ohmic contact layer 12 is specifically an N-type indium gallium arsenide (InGaAs) epitaxial layer, whose lattice constant is between that of indium phosphide (InP) and multiple quantum well structures. Therefore, the N-type indium gallium arsenide epitaxial layer can also serve as a buffer layer to further adjust the lattice matching of subsequent epitaxial layers. Furthermore, the N-type indium gallium arsenide epitaxial layer can optimize carrier injection efficiency. By adjusting its band gap according to the gallium-to-indium ratio, it controls the transport of electrons and holes, ensuring that more carriers are effectively injected into the light-emitting layer, thus enhancing luminous efficiency. In particular, the N-type ohmic contact layer 12 will serve as the interface between the device and the N-type electrode ohmic contact. Therefore, the commonly used dopants in the N-type indium gallium arsenide epitaxial layer are sulfur (S), selenium (Se), or silicon (Si), with doping concentrations typically around 10⁻⁶. 18 Up to 10 20 cm -3 Within this range, such a concentration helps to reduce the Schottky barrier, thus achieving the goal of low-resistance ohmic contacts.

[0055] Next, a first epitaxial composite layer is grown on the N-type ohmic contact layer 12, comprising an N-type indium phosphide (InP) epitaxial layer 13, a first light-emitting layer 14, and a P-type indium phosphide epitaxial layer 15. The first light-emitting layer 14 is formed by sandwiching a multiple quantum well (MQW) structure of indium gallium arsenide phosphide (InGaAsP) quaternary compound semiconductor between the N-type indium phosphide epitaxial layer 13 and the P-type indium phosphide epitaxial layer 15. In this embodiment, the emission wavelength of the multiple quantum well can be 1100–2000 nanometers (nm), preferably 1350 nm, 1450 nm, 1550 nm, and 1600 nm. It should be noted that the materials described in the above embodiment are merely one example, and the present invention is not limited thereto. In practical applications, the materials and their composition can be adjusted according to the emission wavelength. For example, the epitaxial layer can be aluminum indium arsenide (AlInAs), indium gallium arsenide (InGaAs), etc.

[0056] like Figure 1A As shown, a compound semiconductor layer is further epitaxially grown on the epitaxial composite layer. In a specific embodiment, this compound semiconductor layer is a P-type zinc-doped indium gallium arsenide phosphide (Zn-doped InGaAsP) epitaxial layer 16 serving as an ohmic contact layer, with a thickness not exceeding 1 micrometer (μm), preferably... Specifically, the doping concentration of this zinc-doped indium gallium arsenide phosphide epitaxial layer is 10. 18 Up to 10 20 cm -3 Between these concentration ranges, such a range helps to reduce contact resistance to form an ohmic contact with the interface of the subsequent metal layer.

[0057] Secondly, please refer to Figure 1B A metal stack 17 is deposited on a p-type zinc-doped indium gallium arsenide phosphide epitaxial layer 16 by means of evaporation or sputtering. Specifically, the metal stack 17 can be selected from one or a combination of titanium (Ti), platinum (Pt), and gold (Au), with a thickness of less than 1 micrometer, preferably... Next, a patterning process is performed on the metal stack 17 so that the metal stack 17 is appropriately distributed in the first epitaxial composite layer according to the design pattern of the subsequent light-emitting diode electrodes, serving as a conductive anchor for the uniform diffusion of subsequent longitudinal current inside the light-emitting diode. Next, please refer to... Figure 1C The first transparent conductive layer 18 is formed on the wafer surface, covering the first epitaxial composite layer. More specifically, the first transparent conductive layer 18 covers the P-type zinc-doped indium gallium arsenide phosphide epitaxial layer 16 and the patterned metal stack 17. The first transparent conductive layer 18 is composed of indium tin oxide (ITO), aluminum zinc oxide (AZO), zinc tin oxide (IZO), nickel oxide, indium tin oxide, tin cadmium oxide, tin antimony oxide, or a combination thereof.

[0058] Secondly, prepare a light-emitting diode structure with a second wavelength range, wherein the second wavelength range can be, for example, but is not limited to, 1000–1100 nanometers (nm). See also... Figure 2AThe method uses gallium arsenide (GaAs) as a second epitaxial growth substrate 20. Subsequently, an N-type gallium arsenide layer 21 is formed on the gallium arsenide substrate as a buffer layer. Then, a second epitaxial composite layer is formed on the buffer layer, for example, it can be a double heterostructure of aluminum gallium arsenide (AlGaAs). Specifically, in this embodiment, the second epitaxial composite layer includes an N-type aluminum gallium arsenide (AlGaAs) epitaxial layer 22, a second light-emitting layer 23, and a P-type aluminum gallium arsenide (AlGaAs) epitaxial layer 24. The second light-emitting layer 23 is composed of indium gallium arsenide (InGaAs) as a multiple quantum well (MQW) structure, and in this embodiment, its emission wavelength can be 1000–1100 nanometers (nm). Furthermore, in practical applications, the heteroepitaxial material can also be aluminum gallium indium phosphide (AlGaInP), indium gallium phosphide (InGaP), aluminum gallium arsenide (AlGaAs), indium gallium arsenide (InGaAs), etc. Please continue reading. Figure 2A As shown, a p-type carbon-doped gallium arsenide (GaAs) epitaxial layer 25 is formed on the second epitaxial composite layer as the subsequent ohmic contact layer. The carbon doping concentration in the carbon-doped gallium arsenide epitaxial layer is 4 x 10⁻⁶. 19 ~1.5x10 20 cm -3 This is used to reduce contact resistance. Please refer to [link / reference]. Figure 2B A second transparent conductive layer 28 is formed by deposition to cover the above-mentioned P-type carbon-doped gallium arsenide epitaxial layer 25. The composition of the second transparent conductive layer 28 is the same as that of the first transparent conductive layer 18.

[0059] Please see Figure 3A Next, the first transparent conductive layer 18 on the first epitaxial growth substrate 10 is bonded to the second transparent conductive layer 28 on the second epitaxial growth substrate 20 at high temperature, so that the first transparent conductive layer 18 and the second transparent conductive layer 28 are bonded into a single transparent conductive layer, the total thickness of which is preferably controlled within a certain range. like Figure 3A As shown, clearly, the transparent conductive layer, composed of the first transparent conductive layer 18 and the second transparent conductive layer 28, is sandwiched between the two epitaxial composite layers, enabling the light-emitting diode of the present invention to provide dual-band light. Next, the first epitaxial growth substrate 10 and the buffer layer 11 are removed together, and the second epitaxial growth substrate 20 is positioned at the bottom of the dual-band light-emitting diode structure, as shown. Figure 3B As shown. Subsequently, a meta-etching and etching (MESA) process is performed to etch portions of the N-type ohmic contact layer 12 and the first epitaxial composite layer, exposing a flat surface of the first transparent conductive layer 18 for subsequent placement of the P-type electrode, as shown. Figure 3C As shown.

[0060] Please see Figure 3D A roughening process is performed on the MESA platform to remove part of the N-type ohmic contact layer 12. Next, a metal evaporation process is performed to form a P-type electrode 31 on the exposed surface of the first transparent conductive layer 18, and a first N-type electrode 32 on the unroughened N-type ohmic contact layer 12. The P-type electrode 31 can be a metal stack, such as, but not limited to, a chromium-gold (CrAu) metal stack, a titanium-gold (TiAu) metal stack, or a chromium-titanium-gold (CrTiAu) metal stack, to provide good metal adhesion, ohmic contact, and high conductivity for the P-type electrode. The N-type electrode material can be, for example, but not limited to, a germanium-gold (GeAu) metal stack or a germanium-gold-nickel (GeAuNi) metal stack, to ensure low contact resistance and good stability of the N-type electrode. Please refer to [link to relevant documentation]. Figure 3F Next, in addition to the electrode surface of the predetermined metal wire bonding, a protective layer is formed on the surface of the light-emitting diode element, such as a silicon dioxide (SiO2) layer.

[0061] Please see Figure 3G Depending on the requirements of the device design, the second epitaxial growth substrate 20 is thinned to control the total height of the final light-emitting diode structure to 100-200 micrometers, but it is not limited to this. For example, the second epitaxial growth substrate 20 can be completely removed, making the total height of the light-emitting diode structure less than 100 micrometers. Finally, a second N-type electrode 33 is formed on the side of the thinned second epitaxial growth substrate 20. This second N-type electrode 33 is made of the same material as the aforementioned first N-type electrode 32, and will not be described in detail here. Please refer to... Figure 4 This diagram shows a top view of a frost-band light-emitting diode according to an embodiment of the present invention. Figure 4 The cross-sectional diagram of line segment AA is as follows: Figure 3G The cross-sectional view shown clearly shows several metal stacks 17 acting as conductive anchors, distributed around the first N-type electrode 32, without overlapping in the vertical position, so as to effectively diffuse the current longitudinally and avoid current concentration.

[0062] It should be noted that the dual-band light-emitting diode disclosed in this invention has two light-emitting layers with different wavelengths. When the P-type electrode 31 and the first N-type electrode 32 are connected, current flows through the first transparent conductive layer 18 and the second transparent conductive layer 28 to conduct light into the first light-emitting layer 14, thereby providing light in the first wavelength range. Taking this embodiment as an example, it provides near-infrared light in the range of 1100 to 2000 nanometers (nm), for example, 1350 nanometers (nm) or 1450 nanometers (nm). On the other hand, when the P-type electrode 31 and the second N-type electrode 33 are connected, current flows through the first transparent conductive layer 18 and the second transparent conductive layer 28 to conduct light into the second light-emitting layer 23, thereby providing light in the second wavelength range, for example, providing near-infrared light in the range of 1065 nanometers (nm). When the P-type electrode 31, the first N-type electrode 32, and the second N-type electrode 33 are simultaneously turned on, the first light-emitting layer 14 and the second light-emitting layer 23 can be turned on simultaneously to provide dual-band near-infrared light with a first band and a second band. This achieves the purpose of providing dual-band light in a single light-emitting diode chip, meeting the needs of wearable devices for thin and light-emitting elements and multi-band detection, while also saving related manufacturing costs.

[0063] In a preferred embodiment, during device design, the epitaxial layer providing a longer wavelength range should be positioned above the device structure, while the epitaxial layer providing a shorter wavelength range should be positioned below the device structure. This ensures that when light emitted from the lower epitaxial layer passes through the upper epitaxial layer, the short-wavelength light will not be absorbed by the epitaxial material with a smaller band gap. Conversely, if the longer-wavelength epitaxial layer is positioned below the device structure and the shorter-wavelength epitaxial layer is positioned above, the longer-wavelength light emitted from the lower epitaxial layer will be absorbed by the upper shorter-wavelength epitaxial layer due to its larger band gap, reducing the luminous efficiency of the device.

[0064] Please see Figure 5This diagram illustrates the process of manufacturing a dual-band light-emitting diode according to the present invention. First, in step S01, a first epitaxial composite layer is formed on a first epitaxial growth substrate, and the first epitaxial composite layer has a first light-emitting layer with a first wavelength band. In step S02, a first transparent conductive layer is formed on the first epitaxial composite layer. Next, in step S03, a second epitaxial composite layer is formed on a second epitaxial growth substrate, and the second epitaxial composite layer has a second light-emitting layer with a second wavelength band, wherein the first wavelength band is not less than the second wavelength band. In step S04, a second transparent conductive layer is formed on the second epitaxial composite layer. Finally, in step S05, the first transparent conductive layer and the second transparent conductive layer are bonded, such that the first transparent conductive layer and the second transparent conductive layer are sandwiched between the first epitaxial composite layer and the second epitaxial composite layer, and the first epitaxial composite layer is disposed on top of the second epitaxial composite layer. The descriptions of the relevant components in the aforementioned process steps can be found above and will not be repeated here.

[0065] The above embodiments are merely illustrative of implementation schemes of the present invention and to explain the technical features of the present invention, and are not intended to limit the scope of protection of the present invention. Any changes or equivalent arrangements that can be easily made by those skilled in the art are within the scope of the present invention, and the scope of protection of the present invention should be determined by the claims.

Claims

1. A dual-band light-emitting diode, comprising: A first epitaxial composite layer having a first luminescent layer in a first wavelength band; A second epitaxial composite layer, having a second luminescent layer with a second wavelength band, wherein the first wavelength band is not less than the second wavelength band; and A transparent conductive layer is sandwiched between the first epitaxial composite layer and the second epitaxial composite layer, with the first epitaxial composite layer disposed on the second epitaxial composite layer.

2. The dual-band light-emitting diode as described in claim 1 further includes a P-type electrode disposed on the transparent conductive layer and electrically connected to the transparent conductive layer.

3. The dual-band light-emitting diode as described in claim 1 further comprises a first N-type electrode and a second N-type electrode, wherein the first N-type electrode is disposed on the first epitaxial composite layer and electrically connected to the first light-emitting layer, and the second N-type electrode is disposed on the second epitaxial composite layer and electrically connected to the second light-emitting layer.

4. The dual-band light-emitting diode as described in claim 1, wherein the first epitaxial composite layer further comprises an N-type indium phosphide epitaxial layer and a P-type indium phosphide epitaxial layer, wherein the N-type indium phosphide epitaxial layer and the P-type indium phosphide epitaxial layer sandwich the first light-emitting layer.

5. The dual-band light-emitting diode as described in claim 4, wherein the first epitaxial composite layer further comprises a P-type zinc-doped indium gallium arsenide phosphide epitaxial layer, the P-type zinc-doped indium gallium arsenide phosphide epitaxial layer being sandwiched between the P-type indium phosphide epitaxial layer and the transparent conductive layer.

6. The dual-band light-emitting diode as claimed in claim 1, wherein the second epitaxial composite layer further comprises an N-type aluminum gallium arsenide epitaxial layer and a P-type aluminum gallium arsenide epitaxial layer, wherein the N-type aluminum gallium arsenide epitaxial layer and the P-type aluminum gallium arsenide epitaxial layer sandwich the second light-emitting layer.

7. The dual-band light-emitting diode as claimed in claim 6, wherein the second epitaxial composite layer further comprises a P-type carbon-doped gallium arsenide epitaxial layer, the P-type carbon-doped gallium arsenide epitaxial layer being sandwiched between the P-type aluminum gallium arsenide epitaxial layer and the transparent conductive layer.

8. The dual-band light-emitting diode as claimed in claim 1, wherein the first band is 1100-2000 nm and the second band is 1000-1100 nm.

9. The dual-band light-emitting diode as claimed in claim 1, wherein the thickness of the transparent conductive layer is 3000 to 10000 angstroms.

10. A method for manufacturing a dual-band light-emitting diode, comprising: A first epitaxial composite layer is formed on a first epitaxial growth substrate, the first epitaxial composite layer having a first light-emitting layer in a first wavelength band; A first transparent conductive layer is formed on the first epitaxial composite layer; A second epitaxial composite layer is formed on a second epitaxial growth substrate, the second epitaxial composite layer having a second light-emitting layer with a second wavelength band, wherein the first wavelength band is not less than the second wavelength band; A second transparent conductive layer is formed on the second epitaxial composite layer; and The first transparent conductive layer and the second transparent conductive layer are bonded together, such that the first transparent conductive layer and the second transparent conductive layer are sandwiched between the first epitaxial composite layer and the second epitaxial composite layer, and the first epitaxial composite layer is disposed on the second epitaxial composite layer.

11. The manufacturing method of claim 10 further comprises, after removing the first epitaxial growth substrate, performing a raised-platform etching on the first epitaxial composite layer to expose a portion of the first transparent conductive layer.

12. The manufacturing method of claim 11, further comprising providing a P-type electrode disposed on the exposed first transparent conductive layer and electrically connected to the first transparent conductive layer and the second transparent conductive layer.

13. The manufacturing method of claim 11 further includes providing a first N-type electrode disposed on the first epitaxial composite layer and electrically connected to the first light-emitting layer.

14. The manufacturing method of claim 10 further includes a step of thinning the second epitaxial growth substrate.

15. The manufacturing method of claim 11, further comprising providing a second N-type electrode disposed on the thinned second epitaxial growth substrate and electrically connected to the second light-emitting layer.

16. The manufacturing method of claim 10, wherein the step of providing a first epitaxial composite layer formed on a first epitaxial growth substrate comprises sequentially providing an N-type indium phosphide (InP) epitaxial layer, the first light-emitting layer, and a P-type indium phosphide epitaxial layer on an indium phosphide substrate.

17. The manufacturing method of claim 10, wherein the step of providing a second epitaxial composite layer formed on a second epitaxial growth substrate comprises sequentially providing an N-type aluminum gallium arsenide epitaxial layer, the second light-emitting layer, and a P-type aluminum gallium arsenide epitaxial layer on a gallium arsenide substrate.

18. The manufacturing method of claim 10, wherein the first band is 1100-2000 nm and the second band is 1000-1100 nm.

19. The manufacturing method of claim 10, wherein the total thickness of the first transparent conductive layer and the second transparent conductive layer after bonding is 3000 to 10000 angstroms.

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