CN108987543A - Light emitting element - Google Patents

Abstract

The present invention discloses a light-emitting element, comprising an epitaxial structure, wherein the epitaxial structure comprises a first-type semiconductor layer, a second-type semiconductor layer and a light-emitting layer. The first-type semiconductor layer comprises a first sub-semiconductor layer, the light-emitting layer is arranged between the first-type semiconductor layer and the second-type semiconductor layer, the first sub-semiconductor layer comprises a high-doping portion and a low-doping portion doped with a first-type dopant, the doping concentration of the high-doping portion is greater than 10 ¹⁷ atoms/cubic centimeter and less than or equal to 10 ¹⁸ atoms/cubic centimeter, and the doping concentration of the low-doping portion is less than or equal to 10 ¹⁷ atoms/cubic centimeter.

Description

Light emitting element

technical field

The present invention relates to a light-emitting element, in particular to a light-emitting diode with a high doping concentration portion and a low doping concentration portion.

Background technique

Light emitting diodes (light emitting diodes, LEDs), as high-efficiency light emitting elements, are widely used in various fields. The current manufacturing method of LEDs in the prior art is to sequentially form an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer on a substrate by means of epitaxy, thereby obtaining an epitaxial structure of the LED.

In the epitaxial structure of light-emitting diodes, since the composition materials of the substrate, N-type semiconductor layer, light-emitting layer, and P-type semiconductor layer are different, the lattice mismatch between each material makes each junction accumulate Lots of stress. Furthermore, when the semiconductor layer is doped with a large amount of dopants, the dopants will also press and interfere with the normal arrangement of the crystal lattice of the semiconductor layer, resulting in stress accumulation in the crystal lattice. When the stress accumulated in the junction or in the lattice is too high, defects will be formed on the junction or in the lattice of the epitaxial structure to release the accumulated stress. However, the existence of these defects will cause problems such as increased leakage current or decreased breakdown voltage of the LED, resulting in a decrease in the reliability of the LED.

Contents of the invention

The present invention aims to provide a light-emitting element, especially a light-emitting element with a stress-regulating structure, which is used to reduce defects caused by stress accumulation, and further solve the problem of reduced reliability of light-emitting diodes caused by defects.

A light emitting device according to an embodiment of the present invention includes an epitaxial structure. The epitaxial structure includes a first-type semiconductor layer, a second-type semiconductor layer, and a light-emitting layer. The first-type semiconductor layer includes a first sub-semiconductor layer. The light-emitting layer is disposed between the first-type semiconductor layer and the second-type semiconductor layer. A sub-semiconductor layer has a high-doped portion and a low-doped portion doped with a first-type dopant, and the doping concentration of the first-type dopant in the high-doped portion is greater than 10 ¹⁷ atoms/cm3 and less than or equal to 10 ¹⁸ atoms/cubic centimeter, the doping concentration of the first-type dopant in the low-doped portion is less than or equal to 10 ¹⁷ atoms/cubic centimeter.

To sum up, the light-emitting device according to one embodiment of the present invention reduces the stress accumulation in the epitaxial structure by having the highly doped portion and the low doped portion with a large difference in doping concentration, thereby reducing the number of defects in the epitaxial structure. In this way, the problem that the reliability of the light-emitting element is reduced due to defects is solved.

The above descriptions about the content of the present invention and the following descriptions of the embodiments are used to demonstrate and explain the spirit and principle of the present invention, and provide further explanations of the claims of the present invention.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a light emitting device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of the doping concentration distribution of the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a light emitting device according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram of the doping concentration distribution of the second embodiment of the present invention.

5 is a schematic cross-sectional view of an epitaxial structure and a substrate in a second embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a light emitting element according to a third embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a light emitting element according to a fourth embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of a light emitting element according to a fifth embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view of a light emitting element according to a sixth embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view of a light emitting element according to a seventh embodiment of the present invention.

Among them, reference signs

1, 2, 3, 4, 5, 6, 7 light emitting elements

100 first electrode

200 Second electrode

300 luminous layers

400 first type semiconductor layer

410 First sub-semiconductor layer

411 Highly doped part

412 Low doping part

420 second sub-semiconductor layer

430 carrier supply layer

440 current spreading layer

500 Type II semiconductor layer

600 substrates

700 buffer layers

A through hole

B insulating layer

T Thickness

Detailed ways

The detailed features and advantages of the present invention are described in detail in the following embodiments, which are sufficient to enable those skilled in the art to understand the technical content of the present invention and implement it accordingly, and according to the disclosed content, patent scope and drawings of this specification , those skilled in the art can easily understand the related objects and advantages of the present invention. The following examples are used to further describe the viewpoints of the present invention in detail, but not to limit the scope of the present invention in any viewpoint.

Firstly, the light emitting element 1 of the first embodiment of the present invention will be described, please refer to FIG. 1 and FIG. 2 . FIG. 1 is a schematic cross-sectional view of a light emitting device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of the doping concentration distribution of the first embodiment of the present invention. The light emitting element 1 of the first embodiment of the present invention includes an epitaxial structure. The epitaxial structure includes a first-type semiconductor layer 400 , a second-type semiconductor layer 500 , and a light-emitting layer 300 disposed between the first-type semiconductor layer 400 and the second-type semiconductor layer 500 . The thickness T of the epitaxial structure is preferably no more than 6 microns, and the thickness of the epitaxial structure is usually greater than 1 micron. Too thick or too thin will affect the yield of subsequent processes. The maximum width of the light-emitting element 1 is between 1 and 100 microns, preferably between 3 and 30 microns, that is, the light-emitting element 1 in the first embodiment is a micron-scale micro light-emitting element (Micro LED ).

The doping types of the first-type semiconductor layer 400 and the second-type semiconductor layer 500 are different. For example, the first-type semiconductor layer 400 is mainly doped with first-type dopants, and the first-type dopants include group IVA elements, such as silicon (Si), carbon (C) or germanium (Ge). , so the first-type semiconductor layer 400 is an N-type doped semiconductor layer. The second-type semiconductor layer 500 is mainly doped with second-type dopants, and the second-type dopant includes doping group IIA elements, such as magnesium (Mg), so the second-type semiconductor layer is P-type doped the semiconductor layer. The light-emitting element 1 according to the first embodiment of the present invention will be described below with the first-type semiconductor layer 400 being an N-type doped semiconductor layer and the second-type semiconductor layer 500 being a P-type doped semiconductor layer.

The light emitting layer 300 is, for example, a multiple quantum well (MQW) structure. The material of the light emitting layer 300 is, for example, In _y Ga _1-y N, where 0≦y<1. In the first embodiment of the present invention, the light emitting layer 300 includes a multi-quantum well structure composed of multiple layers of InGaN and GaN, but not limited thereto. The thickness of the light emitting layer 300 is between 0.1 micron and 1 micron, but not limited thereto.

The first type semiconductor layer 400 includes a first sub-semiconductor layer 410 . The material of the first sub-semiconductor layer 410 is a ternary semiconductor material, such as In _x Ga _1-x N, 0<X<1, but not limited thereto. The thickness of the first sub-semiconductor layer 410 is, for example, 50 nanometers (nm) to 250 nanometers. If it is too thick, the epitaxial quality of the light emitting element will be affected, but not limited thereto. In the first embodiment of the present invention, the material of the first sub-semiconductor layer 410 is indium gallium nitride (InGaN), which has a better stress release effect than other materials. The thickness of the first sub-semiconductor layer 410 is 200 nm. In other embodiments of the present invention, the thickness of the first sub-semiconductor layer may be 75 nm, 100 nm, 150 nm, or 225 nm. In particular, in the first example of the present invention, the first sub-semiconductor layer 410 is a single-layer semiconductor layer. In detail, in the images of the electron microscope or the secondary ion mass spectrometer (SIMS), each region in the first sub-semiconductor layer 410 has consistent brightness and darkness.

Please refer to FIG. 2 for the doping concentration distribution of the first type dopant in the first sub-semiconductor layer 410 of the first embodiment of the present invention. The first sub-semiconductor layer 410 has at least one highly doped dopant of the first type dopant The impurity portion 411 and at least one low-doped portion 412 . The first type dopant is the main dopant in the first sub-semiconductor layer 410 . Wherein, the doping concentration of the low-doped portion 412 is less than or equal to 10 ¹⁷ atoms/cm ³ , preferably, the doping concentration of the low-doping portion 412 is less than or equal to 5×10 ¹⁶ atoms/cm 3 , more preferably, the doping concentration of the low-doped portion 412 is less than or equal to 10 ¹⁶ atoms/cubic centimeter. In particular, the doping concentration of the low-doped portion 412 may be close to undoped, but it is not limited thereto. The doping concentration of the highly doped portion 411 is greater than 10 ¹⁷ atoms/cm3 and less than or equal to 10 ¹⁸ atoms/cm3, preferably the doping concentration of the highly doped portion 411 is greater than 5×10 ¹⁷ atoms/cm3 cubic centimeter and less than or equal to 10 ¹⁸ atoms/cubic centimeter, more preferably the doping concentration of the highly doped portion 411 is greater than 8×10 ¹⁷ atoms/cubic centimeter and less than or equal to 10 ¹⁸ atoms/cubic centimeter. Here, the ratio of the doping concentration of the high doping portion 411 to the doping concentration of the low doping portion 412 is greater than 10. Preferably, the ratio of the doping concentration of the high doping portion 411 to the doping concentration of the low doping portion 412 is greater than or equal to 10 ² . By having the highly doped portion 411 and the low doped portion 412 with a large difference in doping concentration, the stress generated during epitaxy is reduced. In particular, the ratio of the doping concentration of the highly doped part 411 to the doping concentration of the low doped part 412 is, for example, the highest doping concentration in the highly doped part 411 and the doping concentration in the low doped part 412. The concentration with the lowest doping concentration was compared. In the light-emitting element of the first embodiment of the present invention, the first-type semiconductor layer 410 is an N-type semiconductor layer, and the doping concentrations of the highly doped part 411 and the low-doped part 412 of the first sub-semiconductor layer 410 are both of the first type. The doping concentration of the dopant, the first type dopant is silicon, but not limited thereto.

In the first embodiment of the present invention, the low-doped portion 412 is disposed between the high-doped portion 411 and the light-emitting layer 300 , but not limited thereto. In other embodiments of the present invention, the highly doped portion may be disposed between the low doped portion and the light emitting layer.

In the first embodiment of the present invention, the numbers of the highly doped portion and the low doped portion are both one. Here, in a direction perpendicular to the light-emitting element 1, the low-doped portion 412 covers the high-doped portion 411, that is, the low-doped portion 412 and the high-doped portion 411 are formed when the first sub-semiconductor layer 410 is epitaxially grown. Formed in different stages, but not limited thereto. In the first embodiment of the present invention, based on the direction from the surface of the first-type semiconductor layer 400 in contact with the light-emitting layer 300 to the direction away from the light-emitting layer 300, the parts with thicknesses D1 to D4 correspond to the first-type semiconductor layer 400, and the thickness D2 The portion from D3 to D3 corresponds to the low-doped portion 412 , and the portion from D3 to D4 corresponds to the highly-doped portion 411 . The low-doped portion 412 is disposed between the high-doped portion 411 and the light-emitting layer 300 , but not limited thereto. In other embodiments of the present invention, the highly doped portion 411 may be disposed between the low doped portion 412 and the light emitting layer 300 .

In the first embodiment of the present invention, the thickness ( D2 - D3 ) of the low-doped portion 412 accounts for 10% to 95% of the thickness ( D1 - D4 ) of the first sub-semiconductor layer 410 . Preferably, the thickness of the low-doped portion 412 accounts for 60% to 95% of the thickness of the first sub-semiconductor layer 410 . More preferably, the thickness of the low-doped portion 412 accounts for 80% to 95% of the thickness of the first sub-semiconductor layer 410 . The higher the ratio of the thickness of the low-doped portion 412 to the thickness of the first sub-semiconductor layer 410 is, the better the electrical properties of the light-emitting element 1 of the present invention can be. In other embodiments of the present invention, the first sub-semiconductor layer may have multiple highly doped parts and multiple low doped parts, and the multiple highly doped parts and the multiple low doped parts are arranged alternately with each other, and the low doped parts The total thickness of the part accounts for 10% to 95% of the thickness of the first sub-semiconductor layer, preferably the total thickness of the low-doped part accounts for 60% to 95% of the thickness of the first sub-semiconductor layer, more preferably low The total thickness of the doped part accounts for 80% to 95% of the thickness of the first sub-semiconductor layer.

The second type semiconductor layer 500 is disposed on a side of the light emitting layer 300 away from the first type semiconductor layer 400 . The material of the second-type semiconductor layer 500 may include III-V group nitride materials, such as gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN), nitride Aluminum Gallium (AlGaN) or Aluminum Indium Gallium Nitride (AlInGaN). The material of the second-type semiconductor layer 500 is preferably gallium nitride (GaN) or aluminum gallium nitride (AlGaN). The second-type dopant is the main dopant in the second-type semiconductor layer 500 . In the first embodiment of the present invention, the second-type semiconductor layer 500 is a P-type semiconductor layer, and the second-type dopant is magnesium, but not limited thereto.

Since the first sub-semiconductor layer 410 of a single layer has a highly doped portion 411 and a low doped portion 412 at the same time, and the doping concentration of the highly doped portion 411 is relatively different from that of the low doped portion 412. If the difference is large, the degree to which the lattice arrangement of the low-doped portion 412 is disturbed by the dopant is lower than the degree to which the lattice arrangement of the high-doped portion 412 is disturbed by the dopant. In this way, the stress accumulated in the lattice of the low-doped portion 412 is smaller than the stress accumulated in the lattice of the highly-doped portion 411 , and the stress accumulated in the epitaxial structure is in the low-doped portion 412 of the first sub-semiconductor layer 410 buffer and release in order to prevent a large amount of stress from continuously accumulating in the light-emitting layer 300 . The higher the ratio of the thickness of the low-doped portion 412 to the thickness of the first sub-semiconductor layer 410 is, the better the effect of the low-doped portion 412 on buffering and releasing stress is. Through the low-doped portion 412 disposed in the first sub-semiconductor layer 410, the defects generated in the light-emitting layer 300 due to stress accumulation are reduced, so that the defect density in the light-emitting layer 300 is, for example, between 10 ⁴ /cm ² and 10 ⁸ /cm 2 ^cm2 between. Thereby, the luminous uniformity, luminous intensity and breakdown voltage of the light-emitting element 1 are improved, and the leakage current is improved, so that the overall electrical performance and reliability of the light-emitting element are improved.

Next, the light emitting element of the second embodiment of the present invention will be described, please refer to FIG. 3 to FIG. 5 . FIG. 3 is a schematic cross-sectional view of a light emitting device according to a second embodiment of the present invention. FIG. 4 is a schematic diagram of the doping concentration distribution of the second embodiment of the present invention. 5 is a schematic cross-sectional view of an epitaxial structure and a substrate in a second embodiment of the present invention. The light emitting element includes a first electrode 100 , a second electrode 200 , and an epitaxial structure disposed between the first electrode 100 and the second electrode 200 . The first electrode 100 and the second electrode 200 are, for example, high work function metals such as platinum, nickel, titanium, gold, chromium, silver, the above alloys and combinations of the above materials, metal oxides such as indium tin oxide and zinc oxide, or conductive Non-metallic materials such as conductive polymers, graphite, graphene and black phosphorus. The high work function metal is, for example, a metal material with a work function not less than 4.5 eV. The light emitting device 2 of the second embodiment of the present invention is a vertical light emitting device, and the epitaxial structure is disposed between the first electrode 100 and the second electrode 200 , but not limited thereto. In other embodiments of the present invention, the light emitting element can also be a horizontal light emitting element or other types of light emitting elements. The maximum width of the light-emitting element 2 is between 1 and 100 microns, preferably between 3 and 30 microns, that is, the light-emitting element 2 in the second embodiment is a micron-scale micro light-emitting element (Micro light-emitting element). LED). Furthermore, a maximum peak current density of an external quantum efficiency curve of the light-emitting device 2 according to the second embodiment of the present invention is preferably between 0.01A/cm ² and 2A/cm ² . That is, the light-emitting element of the present invention is suitable for operation at a low current density.

Please refer to FIG. 3 , the epitaxial structure includes a light-emitting layer 300 , a first-type semiconductor layer 400 disposed between the light-emitting layer 300 and the first electrode 100 , and a second-type semiconductor layer disposed between the light-emitting layer 300 and the second electrode 200 . Semiconductor layer 500. The thickness T of the epitaxial structure is preferably no more than 6 microns, and the thickness T of the epitaxial structure is usually greater than 1 micron. Too thick or too thin will affect the yield of subsequent processes. In the following, the first electrode is 100 as an N-type electrode, the second electrode as 200 is a P-type electrode, the first-type semiconductor layer 400 is an N-type doped semiconductor layer, and the second-type semiconductor 500 is a P-type doped semiconductor Layer, the light-emitting element 2 of the second embodiment of the present invention is described.

The light emitting layer 300 of the second embodiment of the present invention is similar to the light emitting layer 300 of the first embodiment of the present invention, and the description of the light emitting layer 300 will not be repeated here.

In addition to the first sub-semiconductor layer 410, the first-type semiconductor layer 400 further includes a second sub-semiconductor layer 420 disposed between the first electrode 100 and the first sub-semiconductor layer 410, and a second sub-semiconductor layer 420 disposed between the light-emitting layer 300 and the first sub-semiconductor layer. The carrier supply layer 430 between the semiconductor layers 410 and the current diffusion layer 440 disposed on the side of the second sub-semiconductor layer 420 away from the first sub-semiconductor layer 410 .

The material of the first sub-semiconductor layer 410 is similar to the material of the first sub-semiconductor layer 410 in the first embodiment of the present invention, and will not be repeated here. Please refer to FIG. 4 for the doping concentration distribution of the first type dopant of the light-emitting device 2 according to the second embodiment of the present invention. The first sub-semiconductor layer 410 has at least one highly doped portion 411 and at least one lowly doped portion 412 . In the second embodiment of the present invention, taking the direction of the second-type semiconductor layer 500 away from the surface of the light-emitting layer 300 toward the first-type semiconductor layer 400 as a reference, the part with a thickness of D1 to D4 corresponds to the first-type semiconductor layer 400, The portion with thickness D2 to D3 corresponds to the low doped portion 412 , and the portion with thickness D3 to D4 corresponds to the highly doped portion 411 . The part with thickness D5 to D6 corresponds to the light emitting layer 300 . The portion of thickness D6 to D1 corresponds to the carrier supply layer 430 . The part with thickness D4 to D7 corresponds to the second sub-semiconductor layer 420 . The portion of the thickness D7 away from the thickness D4 is the current spreading layer 440 .

In the second embodiment of the present invention, the highly doped part 411 is disposed between the low doped part 412 and the second semiconductor layer 420 , but not limited thereto. In other embodiments of the present invention, the low-doped portion may be disposed between the high-doped portion and the second-type semiconductor layer. The doping concentration relationship and thickness relationship between the highly doped portion 411 and the low doping portion 412 in the second embodiment of the present invention is similar to the doping concentration of the high doping portion 411 and the low doping portion 412 in the first embodiment of the present invention The relationship and the thickness relationship will not be repeated here.

The second sub-semiconductor layer 420 is disposed between the first electrode 100 and the first sub-semiconductor layer 410 . The material of the second sub-semiconductor layer 420 is, for example, Al _r Ins Ga _{1-rs N} , r≧0, s≧0 and 1≧r+s≧0, but not limited thereto. The thickness of the second sub-semiconductor layer 420 is, for example, 50 nanometers (nm) to 100 nanometers, but not limited thereto. In the second embodiment of the present invention, the material of the second sub-semiconductor layer 420 is gallium nitride (GaN), and the thickness of the second sub-semiconductor layer 420 is 80 nanometers. In other embodiments of the present invention, the material of the second sub-semiconductor layer is InGaN, AlGaN or AlInGaN. In particular, the second sub-semiconductor layer 420 may be a single-layer semiconductor layer.

The second sub-semiconductor layer 420 contains the first type dopant. In the second embodiment of the present invention, the second sub-semiconductor layer 420 is an N-type semiconductor layer, and the first-type dopant is silicon, but not limited thereto. The doping concentration of the first type dopant in the second sub-semiconductor layer 420 is higher than the doping concentration of the first type dopant in the highly doped portion 411 . Furthermore, in the second sub-semiconductor layer 420, the doping concentration of the first-type dopant is greater than 10 ¹⁸ atoms/cm3 and less than or equal to 10 ²⁰ atoms/cm3, preferably, the first-type dopant The doping concentration is greater than 10 ¹⁸ atoms/cubic centimeter and less than or equal to 10 ¹⁹ atoms/cubic centimeter. In the second embodiment of the present invention, the position of the second sub-semiconductor layer 420 corresponds to the part with thicknesses D4 to D7 in FIG. 4 . Since the doping concentration of the second sub-semiconductor layer 420 is higher than that of the highly doped portion 411 in the first sub-semiconductor layer 410, the second sub-semiconductor layer 420 can further increase the number of carriers in the first-type semiconductor layer 400 quantity, so as to further increase the luminous intensity of the luminescent layer 300 .

The carrier supply layer 430 is disposed between the light emitting layer 300 and the first sub-semiconductor layer 410 . The material of the carrier supply layer 430 is, for example, Al _r In _s Ga _1-rs N, r≧0, s≧0 and 1≧r+s≧0, but not limited thereto. The thickness of the carrier supply layer 430 is, for example, 10 nanometers (nm) to 30 nanometers. If it is too thick, defects will be generated in the subsequent epitaxially grown semiconductor layer. In the second embodiment of the present invention, the material of the carrier providing layer 430 is gallium nitride (GaN), and the thickness of the carrier providing layer 430 is 20 nanometers. In other embodiments of the present invention, the material of the carrier supply layer is InGaN, AlGaN or AlInGaN. In particular, the carrier supply layer 430 may be a single-layer semiconductor layer.

The carrier supply layer 430 includes a first-type dopant and a second-type dopant, and the doping concentration of the first-type dopant is greater than that of the second-type dopant. In the second embodiment of the present invention, the carrier supply layer 430 is an N-type semiconductor layer, the first-type dopant is silicon, and the second-type dopant is magnesium, but not limited thereto. The doping concentration of the first type dopant in the carrier supply layer 430 is higher than the doping concentration of the first type dopant in the highly doped portion 411 . Furthermore, in the carrier supply layer 430, the doping concentration of the first-type dopant is greater than 10 ¹⁸ atoms/cubic centimeter and less than or equal to 10 ²⁰ atoms/cubic centimeter, preferably, the first-type dopant The doping concentration is greater than 10 ¹⁸ atoms/cubic centimeter and less than or equal to 10 ¹⁹ atoms/cubic centimeter. The doping concentration of the second type dopant in the carrier providing layer 430 is less than 10 ¹⁸ atoms/cm 3 . In other embodiments of the present invention, there may be only the first type dopant in the carrier supply layer. Since the doping concentration of the first type dopant in the carrier supply layer 430 is higher than the doping concentration of the first type dopant in the highly doped portion 411, the carrier supply layer 430 can further increase the density of the first type semiconductor layer 400. The number of carriers in the light-emitting layer 300 can further increase the light-emitting intensity.

The current spreading layer 440 is disposed on a side of the second sub-semiconductor layer 420 away from the first sub-semiconductor layer. The material of the current spreading layer 440 is Al _r In _s Ga _1-rs N, r≧0, s≧0 and 1≧r+s≧0. The thickness of the current spreading layer 440 is, for example, 1 micron (μm) to 3 microns, but not limited thereto. The doping concentration of the first type dopant in the current spreading layer 440 is different from the doping concentration of the first type dopant in the second sub-semiconductor layer 420 . In most regions of the current diffusion layer 440 , the doping concentration of the first-type dopant is preferably higher than that of the first-type dopant in the second sub-semiconductor layer 420 . In the second embodiment of the present invention, the material of the current diffusion layer 440 is GaN, and the current diffusion layer 440 is an N-type doped semiconductor layer with a thickness of 2 micrometers, the second-type dopant is silicon, and the second-type dopant The doping concentration is greater than 10 ¹⁹ atoms/cubic centimeter, but not limited thereto.

In the second embodiment of the present invention, the current diffusion layer 440 is disposed between the first electrode 100 and the second sub-semiconductor layer 420 , but not limited thereto. In other embodiments of the present invention, the first electrode and the second sub-semiconductor layer may also be disposed on the same side of the current diffusion layer. With the help of the current diffusion layer 440 , the current entering the current diffusion layer 440 from the first electrode 100 can be more evenly distributed into the first-type semiconductor layer 400 , thereby making the luminous intensity distribution of the light emitting layer 300 more uniform.

In the second embodiment of the present invention, the first type dopant doped in the first sub-semiconductor layer 410, the second sub-semiconductor layer 420, the carrier supply layer 430 and the current diffusion layer 440 are all silicon, but not This is the limit. In other embodiments of the present invention, the first type dopant doped in the first sub-semiconductor layer, the second sub-semiconductor layer, the carrier supply layer and the current diffusion layer may be different first type dopants, The first type dopant can be silicon or carbon.

The second sub-semiconductor layer 420 and the current diffusion layer 440 are doped with a large amount of dopants, so that the lattice arrangement of the second sub-semiconductor layer 420 and the current diffusion layer 440 is disturbed by the dopant, resulting in stress accumulation in the second sub-semiconductor layer 420 and the current diffusion layer 440. In the crystal lattice of the semiconductor layer 420 and the current spreading layer 440 . In the first sub-semiconductor layer 410, the difference between the doping concentration of the highly doped part 411 and the doping concentration of the low doped part 412 is large, and the lattice arrangement of the low doped part 412 is less disturbed by dopants than The degree to which the lattice arrangement of the highly doped portion 411 is disturbed by the dopant. In this way, the stress accumulated in the lattice of the low-doped portion 412 is smaller than the stress accumulated in the lattice of the highly-doped portion 411 .

The stress accumulated in the second sub-semiconductor layer 420 and the current diffusion layer 440 is buffered and released in the low-doped portion 412 of the first sub-semiconductor layer 410, preventing a large amount of stress from continuing to accumulate in the carrier supply layer 430 and the light-emitting layer 300 middle. The higher the ratio of the thickness of the low-doped portion 412 to the thickness of the first sub-semiconductor layer 410 is, the better the effect of the low-doped portion 412 on buffering and releasing stress is. Through the low-doped portion 412 disposed in the first sub-semiconductor layer 410, the defects caused by the accumulation of stress in the light-emitting layer 300 are reduced, the light-emitting uniformity, light-emitting intensity and breakdown voltage of the light-emitting element 2 are improved, and the leakage current situation is improved. , so that the overall electrical performance of the light-emitting element is improved.

The second type semiconductor layer 500 is disposed on a side of the light emitting layer 300 away from the first type semiconductor layer 400 . The material of the second-type semiconductor layer 500 may include III-V group nitride materials such as gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN), aluminum nitride gallium (AlGaN) or aluminum indium gallium nitride (AlInGaN). The material of the second-type semiconductor layer 500 is preferably gallium nitride (GaN) or aluminum gallium nitride (AlGaN). In the second embodiment of the present invention, the second-type semiconductor layer 500 is a P-type semiconductor layer, the second-type dopant is magnesium, and the doping concentration of the second-type dopant is between 10 ¹⁹ atoms/cubic centimeter to 10 ²⁰ atoms/cubic centimeter, but not limited thereto. In the second embodiment of the present invention, the second electrode 200 is disposed on a side of the second-type semiconductor layer 500 away from the light-emitting layer 300 , but not limited thereto.

The epitaxial structure is disposed on the buffer layer 700 of the substrate 600 through a semiconductor process. Please refer to FIG. 5 for a schematic diagram of the stacking sequence of the substrate 600 , the buffer layer 700 and the epitaxial structure. In detail, the second sub-semiconductor layer 420 , the first sub-semiconductor layer 410 , the carrier supply layer 430 , the light emitting layer 300 and the second-type semiconductor layer 500 are arranged layer by layer on the buffer layer 700 away from the substrate 600 side to obtain the epitaxial structure in the second embodiment of the present invention.

The material of the substrate 600 is, for example, sapphire, silicon, silicon carbide, glass, ceramics, and other materials whose lattice structure matches that of the buffer layer 700 , but is not limited thereto. In other embodiments of the present invention, when the lattice structure of the substrate material matches the lattice structure of the current spreading layer, the current spreading layer can be directly formed on the substrate.

The buffer layer 700 is disposed on the surface of the substrate 600 . The material of the buffer layer 700 is, for example, unintentionally doped gallium nitride (GaN), but not limited thereto. The degree of lattice matching between the lattice structure of the buffer layer 700 and the lattice structure of the substrate 600, and the degree of lattice matching between the lattice structure of the buffer layer 700 and the lattice structure of the current spreading layer 440, both Higher than the lattice matching degree between the lattice structure of the substrate 600 and the lattice structure of the current spreading layer 440 . Thereby, the lattice arrangement of the current spreading layer 440 is relatively orderly, and the number of defects in the current spreading layer 440 is reduced accordingly, so that the current distribution in the current spreading layer 300 is relatively uniform. In an embodiment not shown, between the buffer layer 700 and the substrate 600 may further include a nucleation layer matching the lattice structure of the substrate 600, such as unintentionally doped aluminum nitride (AlN), The lattice arrangement of the subsequent epitaxial structure can be made more orderly.

In the light-emitting element 2 of the second embodiment of the present invention, the first-type semiconductor layer 400 is an N-type doped semiconductor layer, and the concentration of the dopant in the first-type semiconductor layer 400 is the concentration of the N-type dopant. The second-type semiconductor 500 is a P-type doped semiconductor layer, the first electrode 100 is an N-type electrode, and the second electrode 200 is a P-type electrode, but not limited thereto. In the light-emitting element of other embodiments of the present invention, the first-type semiconductor layer is a P-type doped semiconductor layer, the concentration of the dopant in the first-type semiconductor layer is the concentration of the P-type dopant, and the second-type semiconductor layer is It is an N-type doped semiconductor layer, the first electrode is a P-type electrode, and the second electrode is an N-type electrode.

Next, the light emitting element 3 of the third embodiment of the present invention will be described, please refer to FIG. 6 . FIG. 6 is a schematic cross-sectional view of a light emitting element according to a third embodiment of the present invention. The light-emitting element 3 of the third embodiment of the present invention is similar to the light-emitting element 2 of the second embodiment of the present invention, but the light-emitting element 3 of the third embodiment of the present invention is not provided with the second sub-semiconductor layer and the carrier supply layer.

In detail, the light-emitting element 3 of the third embodiment of the present invention is a vertical light-emitting element, including a first electrode 100, a second electrode 200, a light-emitting layer 300 disposed between the first electrode 100 and the second electrode 200, a set The first sub-semiconductor layer 410 between the first electrode 100 and the light-emitting layer 300, the current diffusion layer 440 disposed between the first electrode 100 and the first sub-semiconductor layer 410, and the second electrode 200 and the light-emitting layer 300 between the second type semiconductor layer 500 .

Next, the light emitting element 4 of the fourth embodiment of the present invention will be described, please refer to FIG. 7 . FIG. 7 is a schematic cross-sectional view of a light emitting element according to a fourth embodiment of the present invention. The light emitting element 4 of the fourth embodiment of the present invention is similar to the light emitting element 2 of the second embodiment of the present invention, but the light emitting element 4 of the fourth embodiment of the present invention is not provided with a carrier supply layer.

In detail, the light-emitting element 4 of the fourth embodiment of the present invention is a vertical light-emitting element, including a first electrode 100, a second electrode 200, a light-emitting layer 300 disposed between the first electrode 100 and the second electrode 200, and a The first sub-semiconductor layer 410 between the first electrode 100 and the light emitting layer 300, the second sub-semiconductor layer 420 disposed between the first electrode 100 and the first sub-semiconductor layer 410, the second sub-semiconductor layer 420 disposed between the first electrode 100 and the second The current diffusion layer 440 between the two sub-semiconductor layers 420 , and the second-type semiconductor layer 500 disposed between the second electrode 200 and the light emitting layer 300 .

Next, the light emitting element 5 of the fifth embodiment of the present invention will be described, please refer to FIG. 8 . FIG. 8 is a schematic cross-sectional view of a light emitting element according to a fifth embodiment of the present invention. The light emitting element 5 of the fifth embodiment of the present invention is similar to the light emitting element 2 of the second embodiment of the present invention, but the light emitting element 4 of the fourth embodiment of the present invention does not have a second sub-semiconductor layer.

In detail, the light-emitting element 5 of the fifth embodiment of the present invention is a vertical light-emitting element, including a first electrode 100, a second electrode 200, a light-emitting layer 300 disposed between the first electrode 100 and the second electrode 200, a set The first sub-semiconductor layer 410 between the first electrode 100 and the light-emitting layer 300, the carrier supply layer 430 disposed between the light-emitting layer 300 and the first sub-semiconductor layer 410, the carrier supply layer 430 disposed between the first electrode 100 and the first sub-semiconductor layer The current diffusion layer 440 between the semiconductor layers 410 , and the second-type semiconductor layer 500 disposed between the second electrode 200 and the light emitting layer 300 .

Next, the light emitting element 6 of the sixth embodiment of the present invention will be described, please refer to FIG. 9 . FIG. 9 is a schematic cross-sectional view of a light emitting element according to a sixth embodiment of the present invention. The light emitting element 6 of the sixth embodiment of the present invention is similar to the light emitting element 2 of the second embodiment of the present invention.

In detail, the light-emitting element 6 of the sixth embodiment of the present invention is a horizontal light-emitting element, including a current spreading layer 440 , a second-type semiconductor layer 500 , and a light-emitting diode disposed between the current spreading layer 440 and the second-type semiconductor layer 500 . Layer 300, the first sub-semiconductor layer 410 disposed between the current diffusion layer 440 and the light-emitting layer 300, the second sub-semiconductor layer 420 disposed between the current diffusion layer 440 and the first sub-semiconductor layer, and the light-emitting layer 300 The carrier supply layer 430 between the first sub-semiconductor layer 410 , the first electrode 100 connected to the current diffusion layer 440 , and the second electrode 200 connected to the second-type semiconductor layer 500 . The first electrode 100 and the second sub-semiconductor layer 420 are disposed on the same side of the current diffusion layer 440 . Further, the second sub-semiconductor layer 420 is disposed on and covers a part of the surface of the current diffusion layer 440 facing the light-emitting layer 300 , and the first electrode 100 is disposed on and covers another part of the surface of the current diffusion layer 440 facing the light-emitting layer 300 .

Next, the light-emitting element 7 of the seventh embodiment of the present invention will be described, please refer to FIG. 10 . FIG. 10 is a schematic cross-sectional view of a light emitting element according to a seventh embodiment of the present invention. The light emitting element 7 of the seventh embodiment of the present invention is similar to the light emitting element 2 of the second embodiment of the present invention.

The light emitting element includes a current spreading layer 440 , a second type semiconductor layer 500 , a light emitting layer 300 disposed between the current spreading layer 440 and the second type semiconductor layer 500 , a first light emitting layer disposed between the current spreading layer 440 and the light emitting layer 300 The sub-semiconductor layer 410, the second sub-semiconductor layer 420 disposed between the current diffusion layer 440 and the first sub-semiconductor layer, the carrier supply layer 430 disposed between the light-emitting layer 300 and the first sub-semiconductor layer 410, the connection current The first electrode 100 of the diffusion layer 440 and the second electrode 200 connected to the second-type semiconductor layer 500 . The first electrode 100 and the second sub-semiconductor layer 420 are disposed on the same side of the current diffusion layer 440 .

In detail, the epitaxial structure has a through hole A penetrating through the second sub-semiconductor layer 420, the first sub-semiconductor layer 410, the carrier supply layer 430, the light-emitting layer 300 and the second-type semiconductor layer 500, and the current diffusion layer 440 is exposed in the through hole A. An insulating layer B is disposed on the side wall of the through hole A. The material of the insulating layer B is, for example, a dielectric film or a polymer material. For example, the material of the insulating layer B is aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), or silicon nitride (Si ₃ N ₄ ), and combinations thereof. In particular, the Young's modulus of the material of the insulating layer B is smaller than any of the above-mentioned Young's modulus of the epitaxial structure, the first electrode 100, and the second electrode 200, so the subsequent bonding of the light-emitting element 7 to an application device (not shown For example, when it is a display backplane), an insulating material with a large degree of deformation can be used as a buffer during bonding. The first electrode 100 is disposed and electrically connected to the current diffusion layer 440 exposed in the through hole A, and the first electrode 100 penetrates the second sub-semiconductor layer 420, the first sub-semiconductor layer 410, the carrier supply layer 430, and the light emitting layer. 300 and the second type semiconductor layer 500. The first electrode 100 is electrically insulated from the second sub-semiconductor layer 420 , the first sub-semiconductor layer 410 , the carrier supply layer 430 , the light emitting layer 300 and the second-type semiconductor layer 500 through the insulating layer B.

In summary, the light-emitting element of the present invention has a large difference between the doping concentration of the high-doped part and the doping concentration of the low-doped part, so that the accumulated stress of the low-doped part is smaller than that of the high-doped part, and thus the first type The stress accumulated in the semiconductor layer is buffered and released in the low-doped portion, preventing a large amount of stress from continuing to accumulate in the light-emitting layer. In this way, defects in the luminescent layer due to stress accumulation are reduced, luminous uniformity, luminous intensity, and breakdown voltage of the luminescent layer are improved, leakage current is improved, and the overall electrical performance and reliability of the luminescent element are improved.

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (22)

1. A light-emitting element, comprising: An epitaxial structure, comprising: A first-type semiconductor layer, including a first sub-semiconductor layer; a second type semiconductor layer; and a light-emitting layer disposed between the first-type semiconductor layer and the second-type semiconductor layer; Wherein, the first sub-semiconductor layer has a high-doped portion and a low-doped portion doped with a first-type dopant, and the doping concentration of the first-type dopant in the high-doped portion is greater than 10 ¹⁷ atoms/cubic centimeter and less than or equal to 10 ¹⁸ atoms/cubic centimeter, the doping concentration of the first-type dopant in the low-doped portion is less than or equal to 10 ¹⁷ atoms/cubic centimeter. 2. The light-emitting element according to claim 1, wherein the doping concentration of the first type dopant in the highly doped portion is the same as the doping concentration of the first type dopant in the low doped portion The ratio of concentrations is greater than 10. 3. The light-emitting device according to claim 1, wherein the first sub-semiconductor layer is a single-layer semiconductor layer. 4. The light emitting element according to claim 1, wherein the thickness of the first sub-semiconductor layer is 50 nm to 250 nm. 5 . The light-emitting device according to claim 4 , wherein the thickness of the low-doped portion accounts for 10% to 95% of the thickness of the first sub-semiconductor layer. 6 . The light-emitting device according to claim 5 , wherein the thickness of the low-doped portion accounts for 60% to 95% of the thickness of the first sub-semiconductor layer. 7. The light emitting element according to claim 1, wherein the material of the first sub-semiconductor layer is a ternary semiconductor material. 8. The light emitting element according to claim 7, wherein the ternary semiconductor material is InGaN. 9. The light-emitting element according to claim 1, wherein the first-type semiconductor layer further comprises a second sub-semiconductor layer, and the first sub-semiconductor layer is disposed between the light-emitting layer and the second sub-semiconductor layer During this period, the doping concentration of a first-type dopant in the second sub-semiconductor layer is greater than the doping concentration of the first-type dopant in the highly doped portion. 10. The light-emitting element according to claim 9, wherein the doping concentration of the first-type dopant in the second sub-semiconductor layer is greater than 10 ¹⁸ atoms/cm3 and less than or equal to 10 ²⁰ atoms/cm cubic centimeters. 11. The light emitting element according to claim 9, wherein the second sub-semiconductor layer has a thickness of 50 nm to 100 nm. 12. The light-emitting element according to claim 9, wherein the material of the second sub-semiconductor layer is Al _r Ins Ga _{1-rs N} , r≧0, s≧0 and 1≧r+s≧0 . 13. The light-emitting element according to claim 12, wherein the material of the second sub-semiconductor layer is gallium nitride (GaN). 14. The light-emitting element according to claim 1, wherein the first-type semiconductor layer further comprises a carrier supply layer disposed between the first sub-semiconductor layer and the light-emitting layer, the carrier supply layer A doping concentration of a first-type dopant in the highly doped portion is greater than a doping concentration of the first-type dopant in the highly doped portion. 15. The light-emitting element according to claim 14, wherein the doping concentration of the first-type dopant in the carrier supply layer is greater than 10 ¹⁸ atoms/cm3 and less than or equal to 10 ²⁰ atoms/cubic centimeter. 16. The light emitting element according to claim 14, wherein the thickness of the carrier supply layer is 10 nm to 30 nm. 17. The light-emitting element according to claim 14, characterized in that, the material of the carrier supply layer is Al _r In _s Ga _{1-r- s} N, r≧0, s≧0 and 1≧r+s≧ 0. 18. The light-emitting element according to claim 17, wherein the carrier supply layer is made of gallium nitride (GaN). 19. The light-emitting element according to claim 14, wherein the carrier supply layer further comprises a second-type dopant, wherein the first-type dopant is an N-type dopant, and the second-type dopant The second-type dopant is a P-type dopant, and the doping concentration of the first-type dopant is greater than that of the second-type dopant. 20. The light-emitting element according to claim 1, further comprising: a first electrode; and a second electrode; Wherein the epitaxial structure is disposed between the first electrode and the second electrode, the first type semiconductor layer is disposed between the light emitting layer and the first electrode, and the first type semiconductor layer further includes a current diffusion layer , the current spreading layer is disposed between the first sub-semiconductor layer and the first electrode. 21. The light-emitting device according to any one of claims 1-20, wherein the first-type dopants are all N-type dopants. 22. The light-emitting element according to any one of claims 1-20, wherein the thickness of the epitaxial structure is less than or equal to 6 micrometers.