CN211700321U

CN211700321U - LED epitaxial structure with N-type electron blocking layer and LED device

Info

Publication number: CN211700321U
Application number: CN202020712650.XU
Authority: CN
Inventors: 不公告发明人
Original assignee: Focus Lightings Science & Technology Co ltd
Current assignee: Focus Lightings Science & Technology Co ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-10-16
Anticipated expiration: 2030-04-30

Abstract

The utility model provides a LED epitaxial structure and LED device with N type electron barrier layer, LED epitaxial structure includes substrate, non-doping semiconductor layer, compound N type semiconductor layer, multiple quantum well layer and P type semiconductor layer from upwards down in proper order. The composite N-type semiconductor layer sequentially comprises a first N-type semiconductor layer, a composite N-type electron blocking layer and a second N-type semiconductor layer along the epitaxial growth direction. The composite N-type electron blocking layer sequentially comprises a metalized coarsening layer, a pause annealing layer with a concave-convex curved surface structure formed on the surface of the coarsening layer, and a superlattice layer with a concave-convex curved surface structure on the pause annealing layer. The utility model discloses a form the N type electron barrier layer that has unsmooth fine structure, promote the lateral expansion ability of electron carrier, promote LED luminous efficacy.

Description

LED epitaxial structure with N-type electron blocking layer and LED device

Technical Field

The utility model relates to a semiconductor light emitting device field specifically relates to a LED epitaxial structure and LED device with N type electron barrier layer.

Background

As a novel energy-saving and environment-friendly solid-state illumination Light source, a Light Emitting Diode (LED) has the advantages of high energy efficiency, small size, Light weight, fast response speed, long service life and the like, so that the Light Emitting Diode (LED) is widely applied in many fields. Currently, the LED market tends to be smooth and regular, cost control becomes a necessary option for various manufacturers, and as a most direct way of reducing the cost of LED chips, it is almost impossible to reduce the size of a single chip to increase the yield, but in the case of keeping the same design, reducing the chip size will be accompanied with the reduction of the luminance of the product. Therefore, on the premise that the size of a single chip is fixed, how to effectively improve the luminance of the LED by forming a fine structure in the LED, which is beneficial to improving the external quantum efficiency, becomes a key subject of technical practitioners at present.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a LED epitaxial structure and LED device with N type electron barrier layer to through forming the N type electron barrier layer that has unsmooth fine structure, promote the lateral expansion ability of electron carrier, promote LED luminous efficacy.

The utility model provides a LED epitaxial structure with an N-type electronic barrier layer, which sequentially comprises a substrate, a non-doped semiconductor layer, a composite N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer from bottom to top;

the composite N-type semiconductor layer sequentially comprises a first N-type semiconductor layer, a composite N-type electron blocking layer and a second N-type semiconductor layer along the epitaxial growth direction;

the composite N-type electron blocking layer sequentially comprises a metalized coarsening layer, a pause annealing layer with a concave-convex curved surface structure formed on the surface of the coarsening layer, and a superlattice layer with a concave-convex curved surface structure on the pause annealing layer.

As a further improvement of the present invention, the second N-type semiconductor layer and the multiple quantum well layer also have a concave-convex curved surface structure.

As a further improvement of the present invention, the first N-type semiconductor layer and the second N-type semiconductor layer are GaN layers doped with Si, and the doping concentration of the first N-type semiconductor layer is smaller than that of the second N-type semiconductor layer.

As a further improvement of the utility model, the doping concentration of Si of the first N-type semiconductor layer is 1 × 10¹⁹cm^-3The second N-type semiconductor layer has Si doping concentration of 2 × 10¹⁹cm^-3。

As a further improvement of the utility model, the coarsening layer is the alligatoring Al layer, and its thickness scope is 10 ~ 20 nm.

As the utility model discloses a further improvement, the superlattice layer contains the double-deck assembled element of a plurality of, and every assembled element contains an Al layer and an AlGaN layer of locating on it, piles up in proper order between the assembled element, and its number is 15 ~ 30.

As a further improvement of the utility model, in the superlattice layer, every layer the thickness on Al layer is 1nm, every layer the thickness on AlGaN layer is 2nm, every layer Al component content scope is 10 ~ 15% in the AlGaN layer.

As a further improvement of the present invention, the first N-type semiconductor layer and the first transition layer are further disposed between the coarsening layers.

As a further improvement of the present invention, the first transition layer is an AlGaN layer, the thickness range thereof is 10 to 20nm, and the content of the Al component thereof is selected from the edge of the first N-type semiconductor layer to the direction of the coarsening layer gradually changes from 0% to 15%.

As a further improvement of the present invention, a second transition layer is further provided between the superlattice layer and the second N-type semiconductor layer.

As a further improvement of the utility model, the second transition layer is the AlGaN layer, and its thickness scope is 5 ~ 8nm, and its Al component content scope is 10 ~ 15%.

In order to solve the above problem, the utility model also provides a LED device, the LED device includes foretell LED epitaxial structure, N electrode and the P electrode that has N type electron barrier layer, the N electrode with first N type semiconductor layer ohmic contact connects, the P electrode with P type semiconductor layer contact layer ohmic contact connects.

The utility model has the advantages that: by forming the composite N-type electron blocking layer in the N-type GaN layer, the superlattice layer with the concave-convex curved surface structure can realize sufficient transverse expansion and transmission of electron carriers, so that the migration rate of electrons in the LED epitaxial layer is reduced, and the recombination probability of electrons/holes in a light emitting region is effectively increased.

Meanwhile, the periodically stacked superlattice layers form a Distributed Bragg Reflection (DBR) effect structure, light emitted from the multi-quantum well layer is changed into front light emission through reflection at the layers, reflection of the non-doped GaN layer and the substrate, particularly the buffer layer, is not needed, and light attenuation of light transmitted inside the LED epitaxial layer is greatly reduced.

In addition, the multi-quantum well layer serving as the main light emitting layer also forms a concave-convex curved surface structure, so that the surface area in unit volume is increased, the recombination probability of electrons and holes in the multi-quantum well layer can be greatly improved, the light emitting efficiency of the LED chip is obviously improved, and the LED chip is particularly suitable for core particle design which is used for the backlight field and requires lateral light emitting.

Drawings

Fig. 1 is a schematic view of an epitaxial structure of an LED with an N-type electron blocking layer according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an LED device including an LED epitaxial structure with an N-type electron blocking layer according to an embodiment of the present invention.

Fig. 3 is a schematic flow chart of a method for manufacturing an LED epitaxial structure with an N-type electron blocking layer according to a first embodiment of the present invention.

Fig. 4 is a schematic flow chart of a method for manufacturing an LED epitaxial structure with an N-type electron blocking layer according to a second embodiment of the present invention

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be clearly and completely described below with reference to the detailed description of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.

For convenience in explanation, the description herein uses terms indicating relative spatial positions, such as "upper," "lower," "rear," "front," and the like, to describe one element or feature's relationship to another element or feature as illustrated in the figures. The term spatially relative position may encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "above" other elements or features would then be oriented "below" or "above" the other elements or features. Thus, the exemplary term "below" can encompass both a spatial orientation of below and above.

As shown in fig. 1, in an embodiment of the present invention, an LED epitaxial structure with an N-type electron blocking layer includes, from bottom to top, a substrate 1, an undoped semiconductor layer 2, a composite N-type semiconductor layer 3, a multiple quantum well layer 4, and a P-type semiconductor layer 5.

The substrate 1 is made of sapphire, silicon carbide, silicon or a composite substrate 1 made of the materials, and can also be made of other common LED substrate materials.

In some embodiments of the present invention, the substrate 1 is further provided with a nitride buffer layer to reduce lattice mismatch between the substrate 1 and the semiconductor layer, thereby improving the growth quality of the epitaxial layer.

The compound N-type semiconductor layer 3 sequentially includes a first N-type semiconductor layer 31, a compound N-type electron blocking layer 32, and a second N-type semiconductor layer 33 along an epitaxial growth direction.

Further, the first N-type semiconductor layer 31 and the second N-type semiconductor layer 33 are Si-doped GaN layers. The first N-type semiconductor layer 31 has a Si doping concentration less than that of the second N-type semiconductor layer 33. The second N-type semiconductor layer 33 located on the upper layer is located below the multiple quantum well layer 4, the doping concentration of Si is higher, the injection speed of electrons from the first N-type semiconductor layer 31 into the multiple quantum well layer 4 through the composite N-type electron barrier layer 32 and the second N-type semiconductor layer 33 can be slowed down, the lateral expansion of electrons is promoted, the recombination efficiency of electrons and holes in the multiple quantum well layer 4 is improved, and therefore the light emitting efficiency of the LED is improved.

Specifically, in this embodiment, the first N-type semiconductor layer 31 has a Si doping concentration of 1 × 10¹⁹cm^-3The second N-type semiconductor layer 33 has a Si doping concentration of 2 × 10¹⁹cm^-3。

Further, the composite N-type electron blocking layer 32 sequentially includes a metalized roughened layer 322, a stop annealing layer 323 having a concave-convex curved surface structure formed on the surface of the roughened layer 322, and a superlattice layer 324 having a concave-convex curved surface structure on the stop annealing layer 323.

Specifically, in this embodiment, the roughened layer 322 is a roughened Al layer with a thickness ranging from 10 nm to 20nm, and the roughened layer 322 is grown at a low temperature, and then annealed at a high temperature and a high pressure to recrystallize the internal structure, so as to form an irregular rough Al spherical structure on the surface of the roughened layer 322, so as to form a stop annealed layer 323 with a concave-convex curved surface structure, thereby providing a substrate with a concave-convex curved surface structure for the subsequent growth of the epitaxial structure.

More specifically, the superlattice layer 324 includes a plurality of double-layer combination units, each combination unit includes an Al layer 3241 and an AlGaN layer 3241 disposed thereon, and the combination units are stacked in sequence, and the number of the combination units is 15-30. The thickness of the Al layer 3241 is 1nm, the thickness of the AlGaN layer 3242 is 2nm, and the content range of Al components in the AlGaN layer 3242 is 10-15%.

Here, on the one hand, the superlattice layer 324 is grown on the basis of the stop annealing layer 323 forming the concavo-convex curved surface structure, and thus the overall structure also forms a multi-layered concavo-convex curved surface structure. Because the motion of electron carrier along the growth direction of superlattice layer can receive the restraint, more tend and along the cross-section lateral motion between layer and layer, so compare in traditional plane superlattice structure, in the utility model discloses a superlattice layer 324 forms more tortuous interface in finite space for electron carrier lateral expansion transmission is more abundant, with the mobility rate of reduction electron in the LED epitaxial layer, thereby effectively increases electron and hole and is in the recombination probability in the luminous zone of multiple quantum well layer 4. The number of the stacking periods of the superlattice layer 324 is limited to 15-30, so that the superlattice layer 324 can be guaranteed to have enough thickness, transverse expansion of electron carriers is facilitated, the total number of layers can be controlled, the process flow is simplified, and the production cost is controlled.

On the other hand, since the superlattice layer 324 has a stacked structure, and the refractive indexes of the Al layer 3241 and the AlGaN layer 3242 are different, the stacked structure may also form a DBR structure, and since the superlattice layer is located below the multiple quantum well layer 4, light emitted from the multiple quantum well layer 4 is reflected in the layer to become front light, and does not need to be reflected by the undoped semiconductor layer 2 and the substrate 1, especially the buffer layer, so that light attenuation of light transmitted inside the LED epitaxial layer is greatly reduced.

In this embodiment, a first transition layer 321 is further provided between the first N-type semiconductor layer 31 and the roughened layer 322.

Specifically, the first transition layer 321 is an AlGaN layer, the thickness of the AlGaN layer ranges from 10 nm to 20nm, and the content of the Al component of the AlGaN layer gradually changes from 0% to 15% in the direction from the first N-type semiconductor layer 31 to the rough layer 322.

Here, since the lattice constant of AlGaN is smaller than that of GaN, doping of Al is not favorable for GaN crystal growth quality, and the first transition layer 321 with the graded Al composition is used to help transition and buffer the deterioration of lattice quality caused by different doping layers, thereby reducing dislocation and stress at the interface in the epitaxial layer.

In this embodiment, a second transition layer 325 is further provided between the superlattice layer 324 and the second N-type semiconductor layer 33.

Specifically, the second transition layer 325 is an AlGaN layer, the thickness range of the second transition layer is 5 to 8nm, the content range of the Al component of the second transition layer is 10 to 15%, and the thickness of the second transition layer 325 is greater than that of the AlGaN layer 3242.

Here, lattice mismatch is reduced by continuously growing an AlGaN layer with a certain thickness, so that the growth quality of the second N-type semiconductor layer 33 above is improved, and defects formed due to lattice mismatch can be effectively prevented from extending to the multiple quantum well layer 4, thereby further ensuring the light emission efficiency of the LED.

The second N-type semiconductor layer 33 and the multiple quantum well layer 4 also have a concave-convex curved surface structure because they are grown based on a concave-convex curved surface structure.

Here, the mqw layer 4 serving as the main light-emitting layer has an uneven curved surface structure, so that the surface area in a unit volume is increased, and the recombination probability of electrons and holes in the mqw layer can be greatly improved, so that the light-emitting efficiency of the LED chip can be obviously improved, and the mqw layer is particularly suitable for the core particle design requiring lateral light emission in the backlight field.

As shown in fig. 2, the present invention further provides an LED device, which includes the above-mentioned LED epitaxial structure with N-type electron blocking layer, an N electrode 6 and a P electrode 7, wherein the N electrode 6 is in ohmic contact with the first N-type semiconductor layer 31, and the P electrode 7 is in ohmic contact with the P-type semiconductor layer 5.

As shown in fig. 3, the present invention further provides a method for manufacturing an LED epitaxial structure with an N-type electron blocking layer, which includes the steps of:

s10: an undoped semiconductor layer 2 and a first N-type semiconductor layer 31 are sequentially grown on a substrate 1.

The substrate 1 is put into a reaction chamber of metal organic chemical vapor deposition equipment after being pretreated to grow the non-doped semiconductor layer 2 and the first N-type semiconductor layer 31. in some embodiments of the present invention, a nitride buffer layer is further grown on the substrate 1. the first N-type semiconductor layer 31 is a GaN layer doped with Si, and the doping concentration is 1 × 10¹⁹cm^-3。

S20: a roughened layer of metallization 322 is grown over the first N-type semiconductor layer 31.

In this embodiment, the roughened layer 322 is a roughened Al layer, and has a growth temperature range of 400 to 500 ℃, a growth pressure of 100torr, and a growth thickness range of 10 to 20 nm.

Here, it is understood that NH was continuously supplied during the growth of the roughened Al layer₃Since AlN is partially generated during the TMAl cracking growth process, the roughened layer 322 is actually a mixed layer of Al and AlN.

S30: annealing the coarsened layer 322 to form a stop annealed layer 323 having a concave-convex curved surface structure on the surface thereof.

In this embodiment, the annealing temperature of rough layer 322 is 1000 ℃, and the pressure is 500 torr.

S40: a superlattice layer 324 is grown on the stop annealing layer 323, and the superlattice layer 324 forms a concave-convex curved surface structure based on the structure of the stop annealing layer 323.

In this embodiment, the superlattice layer 324 alternately grows the Al layer 3241 and the AlGaN layer 3242 at a growth temperature ranging from 900 to 1000 ℃ and a growth pressure of 100torr, and the Al layer 3241 and the AlGaN layer 3242 are alternately grown by alternately introducing TMGa, wherein the number of growth cycles of the Al layer 3241 and the AlGaN layer 3242 ranges from 15 to 30. The growth thickness of the Al layer 3241 is 1nm, the growth thickness of the AlGaN layer 3242 is 2nm, and the component range of Al in the AlGaN layer 3242 is 10-15%.

S50: a second N-type semiconductor layer 33 and a multiple quantum well layer 4 are sequentially grown over the superlattice layer 324.

The second N-type semiconductor layer 33 and the MQW layer 4 form a concave-convex curved surface structure based on the structure of the superlattice layer 324, the second N-type semiconductor layer 33 has a doping concentration higher than that of the first N-type semiconductor layer 31, the second N-type semiconductor layer 31 is a GaN layer doped with Si and has a doping concentration of 2 × 10¹⁹cm^-3。

S60: a P-type semiconductor layer 5 is grown on the multiple quantum well layer 4.

As shown in fig. 4, for the present invention, another method for preparing an LED epitaxial structure with an N-type electron blocking layer is provided, wherein the growth method shown in fig. 4 is the same as the growth method shown in fig. 3, and the growth shown in fig. 4 further includes:

s11: a first transition layer 321 is grown on the first N-type semiconductor layer 31, and the coarsening layer 322 is grown on the first transition layer 321.

In this embodiment, the first transition layer 321 is an AlGaN layer, the growth temperature is 900 to 1000 ℃, the growth pressure is 100torr, the growth thickness is 10 to 20nm, and the content of Al component gradually changes from 0% to 15% in the direction from the first N-type semiconductor layer 31 to the rough layer 322.

S41: a second transition layer 325 is grown on the superlattice layer 324, and the second N-type semiconductor layer 33 is grown on the second transition layer 325.

In this embodiment, the second transition layer 325 is an AlGaN layer, and has a growth temperature of 900 to 1000 ℃, a growth pressure of 100torr, a growth thickness of 5 to 8nm, and an Al component content of 10 to 15%.

According to the preparation method of the LED epitaxial structure with the N-type electron blocking layer, each step is a continuous epitaxial growth mode, and the mass production realizability is high.

To sum up, the utility model discloses a form compound N type electron barrier layer in N type GaN layer, the superlattice layer that wherein has unsmooth curved surface structure can realize the abundant horizontal extension transmission of electron carrier to reduce electron migration rate in LED epitaxial layer, thereby effectively increase electron/hole at the recombination probability in light zone of sending out.

It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.

The above list of details is only for the feasible embodiments of the present invention, and is not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the technical spirit of the present invention are intended to be included within the scope of the present invention.

Claims

1. The utility model provides a LED epitaxial structure with N type electron barrier layer, LED epitaxial structure includes substrate, non-doping semiconductor layer, compound N type semiconductor layer, multiple quantum well layer and P type semiconductor layer from bottom to top in proper order, its characterized in that:

2. The LED epitaxial structure with an N-type electron blocking layer of claim 1, wherein: the second N-type semiconductor layer and the multi-quantum well layer also have a concave-convex curved surface structure.

3. The LED epitaxial structure with an N-type electron blocking layer of claim 2, wherein: the first N-type semiconductor layer and the second N-type semiconductor layer are Si-doped GaN layers, and the doping concentration of the first N-type semiconductor layer is smaller than that of the second N-type semiconductor layer.

4. The LED epitaxial structure with the N-type electron blocking layer according to claim 3, wherein the first N-type semiconductor layer has a Si doping concentration of 1 × 10¹⁹cm^-3The second N-type semiconductor layer has Si doping concentration of 2 × 10¹⁹cm^-3。

5. The LED epitaxial structure with an N-type electron blocking layer of claim 1, wherein: the coarsening layer is a coarsening Al layer, and the thickness range of the coarsening layer is 10-20 nm.

6. LED epitaxial structure with N-type electron blocking layer according to claim 5, characterized in that: the superlattice layer comprises a plurality of double-layer combined units, each combined unit comprises an Al layer and an AlGaN layer arranged on the Al layer, the combined units are stacked in sequence, and the number of the combined units is 15-30.

7. LED epitaxial structure with N-type electron blocking layer according to claim 6, characterized in that: in the superlattice layer, the thickness of each Al layer is 1nm, the thickness of each AlGaN layer is 2nm, and the content range of Al components in each AlGaN layer is 10-15%.

8. The LED epitaxial structure with an N-type electron blocking layer of claim 1, wherein: and a first transition layer is arranged between the first N-type semiconductor layer and the coarsening layer.

9. LED epitaxial structure with N-type electron blocking layer according to claim 8, characterized in that: the first transition layer is an AlGaN layer, the thickness of the first transition layer ranges from 10 nm to 20nm, and the content of Al component of the first transition layer gradually changes from 0% to 15% along the direction from the first N-type semiconductor layer to the coarsening layer.

10. The LED epitaxial structure with an N-type electron blocking layer of claim 1, wherein: and a second transition layer is arranged between the superlattice layer and the second N-type semiconductor layer.

11. LED epitaxial structure with N-type electron blocking layer according to claim 10, characterized in that: the second transition layer is an AlGaN layer, the thickness of the second transition layer ranges from 5 nm to 8nm, and the content of Al components ranges from 10% to 15%.

12. An LED device comprising the LED epitaxial structure with an N-type electron blocking layer according to any one of claims 1 to 11, an N-electrode and a P-electrode, wherein the N-electrode is connected in ohmic contact with the first N-type semiconductor layer, and the P-electrode is connected in ohmic contact with the P-type semiconductor layer contact layer.