Reversed polarity LED structure

Abstract

The utility model provides a reversed-polarity LED structure, and relates to the technical field of semiconductor devices. The reversed-polarity LED structure comprises an epitaxial structure, the epitaxial structure comprises an N-type limiting layer, an active layer, a P-type limiting layer and a P-type GaP window layer which are sequentially stacked in the growth direction, and the P-type GaP window layer comprises a P-type base layer located on the P-type limiting layer and a P-type pattern surface layer located on the side, away from the P-type limiting layer, of the P-type base layer; and the ITO contact layer is positioned on one side, deviating from the P-type limiting layer, of the P-type pattern surface layer. The ITO contact layer and the P-type pattern surface layer are combined to serve as the P-face ohmic contact structure of the LED structure, the reliability of the P-face ohmic contact structure can be improved, and the light absorption condition of the P-face ohmic contact structure can be effectively reduced. And moreover, the alloying time and the alloying temperature required when the ITO contact layer and the P-type pattern surface layer form the P-surface ohmic contact structure are relatively low, so that the difficulty of the preparation process of the reversed-polarity LED structure is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices, and more particularly to a reverse polarity light-emitting diode (LED) structure. BACKGROUND

[0002] As a new light source in the 21st century, the LED structure has a power consumption of only 1 / 10 of that of an ordinary incandescent lamp and a service life of 100 times longer than that of the incandescent lamp at the same brightness. The LED is a cold light source, has a high light efficiency, a low working voltage, a small power consumption, a small size, and is easy to develop into a light and thin product, has a solid structure and a long service life, and does not contain harmful substances such as mercury and lead, does not cause infrared and ultraviolet pollution, and does not pollute the environment during production and use. Therefore, the semiconductor lamp prepared by using the LED structure has the characteristics of energy saving, environmental protection, and long service life, and will replace the traditional incandescent lamp and fluorescent lamp, like the replacement of the transistor for the electron tube. From the perspectives of saving electric energy and reducing greenhouse gas emissions, and from the perspective of reducing environmental pollution, the LED structure has great potential to replace the traditional lighting light source. Although the LED structure has many advantages, it still has room for improvement. CONTENT OF THE INVENTION

[0003] Therefore, the present application provides a reverse polarity LED structure, which effectively solves the existing technical problems, combines the ITO contact layer and the P-type pattern surface layer as the P-face ohmic contact structure of the LED structure, can improve the reliability of the P-face ohmic contact structure, effectively reduces the light absorption of the P-face ohmic contact structure, and improves the external quantum efficiency of the LED structure. The alloying time and the alloying temperature required for forming the P-face ohmic contact structure by the ITO contact layer and the P-type pattern surface layer are low, and the preparation process difficulty of the reverse polarity LED structure is reduced.

[0004] To achieve the above object, the technical scheme provided by the present application is as follows:

[0005] A reverse polarity LED structure, comprising:

[0006] An epitaxial structure, comprising, in sequence along a growth direction, an N-type confinement layer, an active layer, a P-type confinement layer, and a P-type GaP window layer, the P-type GaP window layer comprising a P-type base layer located on the P-type confinement layer, and a P-type pattern surface layer located on a side of the P-type base layer away from the P-type confinement layer, wherein the P-type pattern surface layer comprises a hollow pattern exposing the P-type base layer;

[0007] An ITO contact layer located on the side of the P-type patterned surface layer away from the P-type confinement layer, the ITO contact layer being hollowed out at the hollowed-out pattern;

[0008] A dielectric film layer located on the side of the hollowed-out pattern and the P-type base layer away from the P-type confinement layer, the dielectric film layer exposing the ITO contact layer;

[0009] A mirror layer located on the side of the ITO contact layer away from the P-type confinement layer;

[0010] A target substrate located on the side of the mirror layer away from the P-type confinement layer;

[0011] And a P-type electrode located on the side of the target substrate away from the P-type confinement layer, and an N-type electrode located on the side of the N-type confinement layer away from the P-type confinement layer.

[0012] Optionally, the doping concentration of the P-type patterned surface layer is greater than the doping concentration of the P-type base layer.

[0013] Optionally, the anti-polarity LED structure further comprises:

[0014] A refractive layer located between the P-type base layer and the dielectric film layer at the hollowed-out pattern.

[0015] Optionally, the refractive layer comprises at least two sub-refractive layers stacked in sequence along the growth direction;

[0016] Along the growth direction, the refractive index of the at least two sub-refractive layers changes in a gradient manner.

[0017] Optionally, along the growth direction, the refractive index of the P-type base layer, the at least two sub-refractive layers, and the dielectric film layer changes in a gradient manner.

[0018] Optionally, the at least two sub-refractive layers comprise:

[0019] An IZO sub-refractive layer and an Al2O3 sub-refractive layer stacked in sequence along the growth direction, wherein the IZO sub-refractive layer is located on the side close to the P-type base layer.

[0020] Optionally, the anti-polarity LED structure further comprises:

[0021] An adhesion layer located between the dielectric film layer and the mirror layer.

[0022] Optionally, the adhesion layer comprises at least two oxide sub-adhesion layers stacked in sequence along the growth direction.

[0023] Optionally, the at least two oxide sub-adhesion layers comprise:

[0024] IZO sub-adhesion layer, Al2O3 sub-adhesion layer and ITO sub-adhesion layer are stacked in sequence along the growth direction, wherein the IZO sub-adhesion layer is located close to the dielectric film layer.

[0025] Optionally, the epitaxial structure further comprises:

[0026] An N-type roughening layer between the N-type confinement layer and the N-type electrode, wherein a surface of the N-type roughening layer away from the P-type confinement layer comprises an electrode region and a roughening region, the N-type electrode is located in the electrode region, and the roughening region comprises a roughening surface of the N-type roughening layer;

[0027] And / or, an ohmic contact layer between the N-type confinement layer and the N-type electrode, the N-type electrode covers the ohmic contact layer, wherein when the epitaxial structure comprises the N-type roughening layer, the ohmic contact layer is between the N-type roughening layer and the N-type electrode.

[0028] Compared with the prior art, the technical scheme provided by the application has at least the following advantages:

[0029] The application provides a reverse polarity LED structure, which comprises: an epitaxial structure, the epitaxial structure comprises an N-type confinement layer, an active layer, a P-type confinement layer and a P-type GaP window layer stacked in sequence along a growth direction, the P-type GaP window layer comprises a P-type base layer located on the P-type confinement layer, and a P-type patterned surface layer located on a side of the P-type base layer away from the P-type confinement layer, wherein the P-type patterned surface layer comprises a hollow pattern exposing the P-type base layer; an ITO contact layer located on a side of the P-type patterned surface layer away from the P-type confinement layer, the ITO contact layer is hollow at a position corresponding to the hollow pattern; a dielectric film layer located in the hollow pattern and on a side of the P-type base layer away from the P-type confinement layer, the dielectric film layer exposes the ITO contact layer; a mirror layer located on a side of the ITO contact layer away from the P-type confinement layer; a target substrate located on a side of the mirror layer away from the P-type confinement layer; and a P-type electrode located on a side of the target substrate away from the P-type confinement layer, and an N-type electrode located on a side of the N-type confinement layer away from the P-type confinement layer.

[0030] As can be seen from the above, the technical scheme provided by the application combines the ITO contact layer and the P-type patterned surface layer as the P-face ohmic contact structure of the LED structure, which not only improves the reliability of the P-face ohmic contact structure, but also effectively reduces the light absorption of the P-face ohmic contact structure, thereby improving the external quantum efficiency of the LED structure. Moreover, the alloying time and alloying temperature required for forming the P-face ohmic contact structure by the ITO contact layer and the P-type patterned surface layer are both low, thereby reducing the difficulty of the preparation process of the reverse polarity LED structure. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only only the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the provided drawings.

[0032] Figure 1 A structure diagram of a reverse polarity LED structure provided by an embodiment of the present application;

[0033] Figure 2 A schematic diagram of a hollow pattern provided by an embodiment of the present application;

[0034] Figure 3 A structure diagram of another reverse polarity LED structure provided by an embodiment of the present application;

[0035] Figure 4 A structure diagram of another reverse polarity LED structure provided by an embodiment of the present application;

[0036] Figure 5 A structure diagram of another reverse polarity LED structure provided by an embodiment of the present application;

[0037] Figures 6a to 6d A structure diagram corresponding to each step in a preparation method of a reverse polarity LED structure provided by an embodiment of the present application;

[0038] Figure 7 A structure diagram of another reverse polarity LED structure provided by an embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] As described in the background, as a new light source for lighting in the 21st century, the power consumption of the semiconductor lamp prepared by using the LED structure is only 1 / 10 of that of the ordinary incandescent lamp at the same brightness, and the service life can be prolonged by 100 times. The LED is a cold light source, which has high light efficiency, low working voltage, small power consumption, small size, can be planar packaged, is easy to develop light and thin products, has a solid structure and a long service life, and the light source itself does not contain harmful substances such as mercury and lead, has no infrared and ultraviolet pollution, and will not pollute the outside world in production and use. Therefore, the semiconductor lamp prepared by using the LED structure has the characteristics of energy saving, environmental protection and long service life, and as the transistor replaces the electron tube, the semiconductor lamp will replace the traditional incandescent lamp and fluorescent lamp, which is also the trend. From the perspective of saving electric energy and reducing greenhouse gas emissions, or from the perspective of reducing environmental pollution, the LED structure as a new type of lighting light source has great potential to replace the traditional lighting light source. Although the LED structure has many advantages, there is still room for improvement.

[0041] Based on this, the embodiment of the present application provides a reverse polarity LED structure, which effectively solves the existing technical problems. The ITO contact layer and the P-type pattern surface layer are combined as the P-face ohmic contact structure of the LED structure, which not only can improve the reliability of the P-face ohmic contact structure, but also can effectively reduce the light absorption of the P-face ohmic contact structure, and improve the external quantum efficiency of the LED structure. And the alloying time and alloying temperature required when the ITO contact layer and the P-type pattern surface layer form the P-face ohmic contact structure are relatively low, which reduces the difficulty of the preparation process of the reverse polarity LED structure.

[0042] To achieve the above object, the technical scheme provided by the embodiment of the present application is as follows, which is specifically combined Figures 1 to 7 The technical scheme provided by the embodiment of the present application is described in detail.

[0043] Combined with Figure 1 and Figure 2 , the structure of the reverse polarity LED structure provided by the embodiment of the present application is shown in Figure 1 , which is a structure schematic diagram of a reverse polarity LED structure provided by the embodiment of the present application, Figure 2 is a schematic diagram of a hollow pattern. The reverse polarity LED structure provided by the embodiment of the present application comprises an epitaxial structure, the epitaxial structure comprises N-type limiting layer 110, active layer 120, P-type limiting layer 130 and P-type GaP window layer which are sequentially stacked along the growth direction Y, the P-type GaP window layer comprises P-type base layer 141 located on the P-type limiting layer 130, and P-type pattern surface layer 142 located on the side of the P-type base layer 141 away from the P-type limiting layer 130, wherein the P-type pattern surface layer 142 comprises a hollow pattern 142a which exposes the P-type base layer 141, such as the hollow pattern 142a shown in Figure 2 .

[0044] The reverse polarity LED structure further includes: an ITO contact layer 200 located on the side of the P-type pattern surface layer 142 facing away from the P-type confinement layer 130, wherein the ITO contact layer 200 is hollowed out at the location corresponding to the hollowed-out pattern 142a; a dielectric film layer 300 located on the hollowed-out pattern 142a and on the side of the P-type base layer 141 facing away from the P-type confinement layer 130, wherein the dielectric film layer 300 exposes the ITO contact layer 200; a mirror layer 400 located on the side of the ITO contact layer 200 facing away from the P-type confinement layer 130; similarly, the mirror layer 400 is also located on the side of the dielectric film layer 300 facing away from the P-type confinement layer 130; and a target substrate 500 located on the side of the mirror layer 400 facing away from the P-type confinement layer 130. In addition, a P-type electrode 610 located on the side of the target substrate 500 opposite to the P-type confinement layer 130, and an N-type electrode 620 located on the side of the N-type confinement layer 110 opposite to the P-type confinement layer 130.

[0045] It should be noted that the P-type patterned surface layer 142 provided in this application embodiment (i.e. Figure 2 The corresponding pattern in gray shadow) and the openwork pattern 142a (i.e. Figure 2 The shapes of patterns (related to black shadows) are not limited to Figure 2 As shown in the figure, in some other embodiments, the P-shaped patterned surface layer 142 and the cutout pattern 142a may also be other patterned shapes, which are not specifically limited in this application. Similarly, the ITO contact layer 200 is located on the side of the P-shaped patterned surface layer 142 opposite to the P-shaped limiting layer 130, and the pattern of the ITO contact layer 200 is the same as that of the P-shaped patterned surface layer 142.

[0046] As can be seen from the above, compared with the existing technology that uses AuBe / AuZn as the P-side contact structure, the technical solution provided in this application combines the ITO contact layer 200 and the P-type patterned surface layer 142 as the P-side ohmic contact structure of the LED structure. This not only improves the reliability of the P-side ohmic contact structure but also effectively reduces the light absorption of the P-side ohmic contact structure, thereby improving the external quantum efficiency of the LED structure. Furthermore, the alloying time and alloying temperature required for the ITO contact layer 200 and the P-type patterned surface layer 142 to form the P-side ohmic contact structure are both lower, thus reducing the difficulty of fabricating the reverse polarity LED structure.

[0047] In some embodiments, the P-type GaP window layer provided by the embodiments of the present application is a non-integral GaP layer, which can reduce the light absorption of the P-type GaP window layer to a certain extent, and can improve the current spreading capability and the voltage reduction performance of the P-type GaP window layer. In addition, the doping concentration of the P-type patterned surface layer 142 is greater than the doping concentration of the P-type base layer 141, so as to further reduce the light absorption of the P-type GaP window layer, thereby improving the light brightness of the anti-polarity LED structure.

[0048] Further, the embodiments of the present application can also optimize the structure of the anti-polarity LED structure shown in Figure 1 based on the anti-polarity LED structure, and improve the performance of the device by setting more optimization layers. Referring to Figure 3 , which is a structural schematic diagram of another anti-polarity LED structure provided by the embodiments of the present application. The anti-polarity LED structure provided by the embodiments of the present application further includes a refractive layer 700 between the P-type base layer 141 and the dielectric film layer 300 at the hollow pattern 142a, so as to improve the light efficiency of the anti-polarity LED structure. In some embodiments, the refractive layer 700 provided by the embodiments of the present application can be flush with the P-type patterned surface layer 142, so as to improve the flatness of the dielectric film layer 300 when the dielectric film layer 300 is subsequently prepared.

[0049] In some embodiments, the refractive layer 700 provided by the embodiments of the present application includes at least two sub-refractive layers stacked in sequence along the growth direction Y; the refractive index of the at least two sub-refractive layers changes in a gradient along the growth direction Y, so as to improve the light efficiency of the anti-polarity LED structure. Optionally, the refractive index of all the sub-refractive layers provided by the embodiments of the present application changes in a gradient which is reduced along the growth direction Y. Further, the refractive index of the P-type base layer 141, the at least two sub-refractive layers and the dielectric film layer 300 changes in a gradient along the growth direction Y, so as to improve the light efficiency of the anti-polarity LED structure. Similarly, the refractive index of the P-type base layer 141, the at least two sub-refractive layers and the dielectric film layer 300 provided by the embodiments of the present application can change in a gradient which is reduced along the growth direction Y. Continue to refer to Figure 3As shown, the at least two sub-refractive layers provided by the embodiment of the present application include: IZO sub-refractive layer 710 and Al2O3 sub-refractive layer 720 which are sequentially stacked along the growth direction Y, wherein the IZO sub-refractive layer 710 is located close to the P-type base layer 141. Wherein the GaP refractive index of the P-type base layer 141 is 2.6, the refractive index of the IZO sub-refractive layer 710 is 2, the refractive index of the Al2O3 sub-refractive layer 720 is 1.7, the dielectric film layer 300 can be a SiO2 dielectric film layer and the refractive index is 1.5. It can be seen that along the growth direction Y, the refractive index of the P-type base layer 141, the IZO sub-refractive layer 710, the Al2O3 sub-refractive layer 720 and the dielectric film layer 300 presents a decreasing gradient change, thereby improving the light extraction efficiency of the reverse polarity LED structure.

[0050] Reference Figure 4 As shown, the structure diagram of another reverse polarity LED structure provided by the embodiment of the present application, wherein the reverse polarity LED structure provided by the embodiment of the present application further includes: an adhesion layer 800 located between the dielectric film layer 300 and the mirror layer 400, thereby improving the adhesion strength between the dielectric film layer 300 and the mirror layer 400. In some embodiments, the adhesion layer 800 provided by the embodiment of the present application can include at least two oxide sub-adhesion layers which are sequentially stacked along the growth direction Y. Wherein the at least two oxide sub-adhesion layers provided by the embodiment of the present application include: IZO sub-adhesion layer 810, Al2O3 sub-adhesion layer 820 and ITO sub-adhesion layer 830 which are sequentially stacked along the growth direction Y, wherein the IZO sub-adhesion layer 810 is located close to the dielectric film layer 300.

[0051] Reference Figure 5 As shown, the structure diagram of another reverse polarity LED structure provided by the embodiment of the present application, wherein the epitaxial structure provided by the embodiment of the present application further includes: N-type roughening layer 910 located between the N-type confinement layer 110 and the N-type electrode 620, wherein the surface of the N-type roughening layer 910 away from the P-type confinement layer 130 includes electrode area and roughening area, the N-type electrode 620 is located in the electrode area, and the roughening area includes the roughening surface of the N-type roughening layer 910, thereby improving the light extraction effect of the reverse polarity LED structure. And ohmic contact layer 920 located between the N-type confinement layer 110 and the N-type electrode 620, the N-type electrode 620 covers the ohmic contact layer 920, thereby improving the ohmic contact performance between the N-type electrode 620 and the epitaxial structure, improving the performance of the reverse polarity LED structure. Wherein when the epitaxial structure includes the N-type roughening layer 910, the ohmic contact layer 920 is located between the N-type roughening layer 910 and the N-type electrode 620.

[0052] It should be noted that the reverse polarity LED structure provided by the embodiments of the present application can include the N-type roughening layer 910 alone, or can include the ohmic contact layer 920 alone, or can include both the N-type roughening layer 910 and the ohmic contact layer 920, and the specific design needs to be made according to the actual application.

[0053] The technical solutions provided by the embodiments of the present application will be described in more detail below in combination with the structure schematic diagrams corresponding to the preparation methods and related steps. Figure 5 and Figures 6a to 6d As shown in the drawings, Figures 6a to 6d is a structure schematic diagram corresponding to each step of a preparation method of a reverse polarity LED structure provided by the embodiments of the present application.

[0054] As shown in the drawings, Figure 6a corresponding to step S1, a buffer layer 20 and an etching stop layer 30 are sequentially deposited on a temporary substrate 10 along a growth direction Y by using a set deposition process, and then an epitaxial structure is deposited on the etching stop layer. The epitaxial structure includes an initial ohmic contact layer 920', an initial N-type roughening layer 910', an N-type confinement layer 110, an active layer 120, a P-type confinement layer 130, and a P-type GaP window layer, the P-type GaP window layer includes a P-type base layer 141 located on the P-type confinement layer 130, and an initial P-type surface layer 142' located on a side of the P-type base layer 141 away from the P-type confinement layer 130, wherein the doping concentration of the initial P-type surface layer 142' is greater than the doping concentration of the P-type base layer 141.

[0055] In some embodiments, the set deposition process provided by the embodiments of the present application can be a metal organic chemical vapor deposition process (MOCVD). The material of the temporary substrate 10 can be GaAs. The material of the buffer layer 20 can be GaAs. The material of the initial ohmic contact layer 920' can be GaAs. The active layer 120 can be a multi-quantum well active layer. The doping concentration of the P-type base layer 141 can be 1×10 18 cm -3 , and the doping concentration of the initial P-type surface layer 142' can be 2×10 18 cm -3 .

[0056] Optionally, the thickness of the P-type GaP window layer provided by the embodiments of the present application can be 5000 angstroms, and the thickness of the initial P-type surface layer 142' can be 1000 angstroms.

[0057] As shown in the drawings, Figure 6bAs shown, corresponding to step S2, an initial ITO contact layer is deposited on the side of the initial P-type surface layer 142' away from the P-type confinement layer 130. Then, a photolithography process is used to etch the initial ITO contact layer and the initial P-type surface layer 142' to form the P-type patterned surface layer 142, the ITO contact layer 200, and the hollow pattern 142a. A refractive layer 700 is formed at the hollow pattern 142a.

[0058] In some embodiments, the initial ITO contact layer and initial P-type surface layer 142' provided in this application can be cleaned with acetone, isopropanol, deionized water, etc., before etching. Then, photolithography can be combined with dry or wet etching processes. The pattern of the etched P-type patterned surface layer 142 and ITO contact 200 can be a regular or irregular shape such as a circle, rhombus, or rectangle; this application does not impose specific limitations on this. Furthermore, in this application, a sputtering machine can be used to sequentially deposit an IZO sub-refractive layer 710 and an Al2O3 sub-refractive layer 720 (the sub-refractive layer can be peeled off after depositing all sub-refractive layers on the entire surface to form individual sub-refractive layers), and the refractive layer 700 can fill the hollow pattern 142a of the P-type patterned surface layer 142.

[0059] Optionally, the thickness of the ITO contact 200 provided in this embodiment can be 100 angstroms. And the thickness of the refractive layer 700 provided in this embodiment can be 1000 angstroms.

[0060] like Figure 6c As shown, corresponding to step S3, an initial dielectric film layer and an initial adhesion layer are deposited on the entire surface of the epitaxial structure. Then, a photolithography process is used to etch the initial dielectric film layer and the initial adhesion layer to form the dielectric film layer 300 and the adhesion layer 800. The dielectric film layer 300 can be made of SiO2. It can be seen that along the growth direction Y, the refractive indices of the P-type substrate 141, the IZO sub-refractive layer 710, the Al2O3 sub-refractive layer 720, and the dielectric film layer 300 exhibit a decreasing gradient, thereby improving the light extraction efficiency of the reverse polarity LED structure. Furthermore, the preparation of the adhesion layer 800 enhances the adhesion strength between the dielectric film layer 300 and the subsequently prepared mirror layer 400.

[0061] Optionally, the adhesion layer 800 provided in this application embodiment may include an IZO sub-adhesion layer 810, an Al2O3 sub-adhesion layer 820, and an ITO sub-adhesion layer 830 sequentially stacked along the growth direction Y. The thickness of the adhesion layer 800 may be 100 angstroms to 200 angstroms.

[0062] like Figure 6dAs shown, corresponding to step S4, the mirror layer 400 is sputtered and the target substrate 500 is bonded, and then the temporary substrate 10, the buffer layer 20 and the etching stop layer 30 are removed. The initial ohmic contact layer 920' is etched to form the ohmic contact layer 920, and the initial N-type roughening layer 910' is roughened to form a roughened surface. Then, the P-type electrode 610 is formed on the side of the target substrate 500 away from the P-type confinement layer 130, and the N-type electrode 620 is formed on the side of the N-type roughening layer 910 away from the P-type confinement layer 130, and the N-type electrode 620 covers the ohmic contact layer 920. Finally, cutting and dicing are performed to form a single reverse polarity LED structure. Among them, the preparation of the roughened surface of the N-type roughening layer 910 can improve the light output effect of the reverse polarity LED structure. In addition, the design that the N-type electrode 620 covers the ohmic contact layer 920 can improve the ohmic contact performance between the N-type electrode 620 and the epitaxial structure, thereby improving the performance of the reverse polarity LED structure.

[0063] Optionally, the mirror layer 400 provided by the embodiment of the present application can be an Ag-TiW-Ti-Pt-Au layer stacked in the growth direction Y. In addition, the material of the target substrate 500 provided by the embodiment of the present application can be Si, and the present application does not make specific limitations in this regard.

[0064] Further referring to Figure 7 As shown, the structure of another reverse polarity LED structure provided by the embodiment of the present application is shown in the structure diagram. The reverse polarity LED structure provided by the embodiment of the present application further includes a protective layer 930 located on the side of the reverse polarity LED structure having the N-type electrode 620, wherein the protective layer 930 exposes the N-type electrode 620. Optionally, the material of the protective layer 930 can be SiN, and the present application does not make specific limitations in this regard.

[0065] The embodiment of the present application provides a reverse polarity LED structure, the reverse polarity LED structure comprises: an epitaxial structure, the epitaxial structure comprises N-type limiting layer, active layer, P-type limiting layer and P-type GaP window layer which are sequentially stacked along the growth direction, the P-type GaP window layer comprises P-type base layer located on the P-type limiting layer, and P-type pattern surface layer located on the side of the P-type base layer away from the P-type limiting layer, wherein the P-type pattern surface layer comprises a hollow pattern exposing the P-type base layer;ITO contact layer located on the side of the P-type pattern surface layer away from the P-type limiting layer, the ITO contact layer is hollow at the hollow pattern;Dielectric film layer located on the hollow pattern and on the side of the P-type base layer away from the P-type limiting layer, the dielectric film layer exposes the ITO contact layer;Mirror layer located on the side of the ITO contact layer away from the P-type limiting layer;Target substrate located on the side of the mirror layer away from the P-type limiting layer;And P-type electrode located on the side of the target substrate away from the P-type limiting layer, and N-type electrode located on the side of the N-type limiting layer away from the P-type limiting layer.

[0066] From the above, the technical scheme provided by the embodiment of the present application combines the ITO contact layer and the P-type pattern surface layer as the P-face ohmic contact structure of the LED structure, which not only improves the reliability of the P-face ohmic contact structure, but also effectively reduces the light absorption of the P-face ohmic contact structure, and improves the external quantum efficiency of the LED structure. Moreover, the alloying time and alloying temperature required for forming the P-face ohmic contact structure by the ITO contact layer and the P-type pattern surface layer are relatively low, thereby reducing the difficulty of the preparation process of the reverse polarity LED structure.

[0067] In the description of the embodiments of the present application, it should be understood that, if the terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0068] In addition, if the terms "first", "second" appear, they are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0069] In the embodiments of the present application, unless specifically defined otherwise, the terms "mount", "connect", "connect", "fix", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection or communication with each other; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0070] In the embodiments of the present application, unless specifically defined otherwise, the first feature is "on" or "under" the second feature. The first and second features can be in direct contact, or the first and second features can be in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be the first feature directly above or obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature "below", "below" and "below" the second feature can be the first feature directly below or obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0071] In the embodiments of the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification and the features of different embodiments or examples without contradiction.

[0072] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A reverse polarity LED structure, characterized in that, The reverse polarity LED structure includes: An epitaxial structure comprising an N-type confinement layer, an active layer, a P-type confinement layer, and a P-type GaP window layer stacked sequentially along the growth direction, wherein the P-type GaP window layer comprises a P-type base layer located on the P-type confinement layer and a P-type patterned surface layer located on the side of the P-type base layer away from the P-type confinement layer, wherein the P-type patterned surface layer comprises a hollowed-out pattern exposing the P-type base layer; An ITO contact layer is located on the side of the surface of the P-shaped pattern that is away from the P-shaped limiting layer, and the ITO contact layer is hollowed out at the location of the hollowed-out pattern. A dielectric film layer located in the hollow pattern and on the side of the P-type base layer away from the P-type limiting layer, the dielectric film layer exposing the ITO contact layer; A mirror layer located on the side of the ITO contact layer opposite to the P-type confinement layer; The target substrate located on the side of the mirror layer opposite to the P-type confinement layer; In addition, a P-type electrode located on the side of the target substrate opposite to the P-type confinement layer, and an N-type electrode located on the side of the N-type confinement layer opposite to the P-type confinement layer.

2. The reverse polarity LED structure according to claim 1, characterized in that, The doping concentration of the P-type patterned surface layer is greater than the doping concentration of the P-type base layer.

3. The reverse polarity LED structure according to claim 1, characterized in that, The reverse polarity LED structure also includes: The perforated pattern is located at the refractive layer between the P-type base layer and the dielectric film layer.

4. The reverse polarity LED structure according to claim 3, characterized in that, The refractive layer includes at least two sub-refractive layers stacked sequentially along the growth direction; Along the growth direction, the refractive index of the at least two sub-refractive layers varies in a gradient.

5. The reverse polarity LED structure according to claim 4, characterized in that, Along the growth direction, the refractive index of the P-type substrate, the at least two sub-refractive layers, and the dielectric film layer varies in a gradient.

6. The reverse polarity LED structure according to claim 4, characterized in that, The at least two sub-refractive layers include: An IZO sub-refractive layer and an Al2O3 sub-refractive layer are sequentially stacked along the growth direction, wherein the IZO sub-refractive layer is located on the side closer to the P-type base layer.

7. The reverse polarity LED structure according to claim 1, characterized in that, The reverse polarity LED structure also includes: An adhesion layer located between the dielectric film layer and the mirror layer.

8. The reverse polarity LED structure according to claim 7, characterized in that, The adhesion layer comprises at least two oxide sub-adhesion layers that are sequentially stacked along the growth direction.

9. The reverse polarity LED structure according to claim 8, characterized in that, The at least two oxide sub-adhesive layers include: An IZO sub-adhesion layer, an Al2O3 sub-adhesion layer, and an ITO sub-adhesion layer are sequentially stacked along the growth direction, wherein the IZO sub-adhesion layer is located on the side closer to the dielectric film layer.

10. The reverse polarity LED structure according to claim 1, characterized in that, The epitaxial structure further includes: An N-type roughening layer is located between the N-type confinement layer and the N-type electrode, wherein the surface of the N-type roughening layer facing away from the P-type confinement layer includes an electrode region and a roughening region, the N-type electrode is located in the electrode region, and the roughening region includes the roughened surface of the N-type roughening layer; And / or, an ohmic contact layer located between the N-type confinement layer and the N-type electrode, wherein the N-type electrode covers the ohmic contact layer, wherein when the epitaxial structure includes the N-type roughening layer, the ohmic contact layer is located between the N-type roughening layer and the N-type electrode.

Images