KR102252991B1 - Nano-sturucture semiconductor light emitting device - Google Patents

Abstract

According to an embodiment of the present invention, a plurality of nano light emitting structures each having a nano core made of a first conductivity type semiconductor, an active layer and a second conductivity type semiconductor layer sequentially positioned on the surface of the nano core, and the plurality of nano light-emitting structures A contact electrode made of a transparent conductive material and a first light-transmitting part made of a material having a first refractive index and filled in the space between the plurality of nano light-emitting structures, disposed on the surface of the second conductive semiconductor layer of the light-emitting structure, and , A nanostructure semiconductor comprising a second light-transmitting part made of a material having a second refractive index greater than the first refractive index, disposed on the first light-transmitting part so as to cover the plurality of nano-light-emitting structures It provides a light emitting device.

Description

Nano structure semiconductor light emitting device{NANO-STURUCTURE SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present invention relates to a semiconductor light emitting device having a three-dimensional nanostructure.

Recently, as a new semiconductor light emitting device technology, semiconductor light emitting devices using nanostructures have been developed. A semiconductor light emitting device using a nano structure (hereinafter referred to as a'nano structure semiconductor light emitting device') not only greatly improves crystallinity, but also can obtain an active layer on a non-polar or semi-polar surface, thereby reducing efficiency due to polarization. Can be prevented. In addition, since it can emit light through a large surface area, light efficiency can be greatly improved. In order to ensure such improved light efficiency, the nanostructured semiconductor light emitting device needs to further improve light extraction efficiency by improving external quantum efficiency.

In the art, there is a need for a three-dimensional nanostructure semiconductor light emitting device in which a light extraction structure configured to fit a unique shape in which a plurality of nano light emitting structures are arranged is introduced.

According to an embodiment of the present invention, a plurality of nano light emitting structures each having a nano core made of a first conductivity type semiconductor, an active layer and a second conductivity type semiconductor layer sequentially positioned on the surface of the nano core, and the plurality of nano light-emitting structures A contact electrode made of a transparent conductive material and a first light-transmitting part made of a material having a first refractive index and filled in the space between the plurality of nano light-emitting structures, disposed on the surface of the second conductive semiconductor layer of the light-emitting structure, and , A nanostructure semiconductor comprising a second light-transmitting part made of a material having a second refractive index greater than the first refractive index, disposed on the first light-transmitting part so as to cover the plurality of nano-light-emitting structures It provides a light emitting device.

The second light-transmitting part further includes a plate disposed on the first light-transmitting part to cover the plurality of nano light-emitting structures, and the plurality of lenses may be arranged on the plate. Alternatively, the plurality of lenses may be disposed on the first light-transmitting part so as to cover the plurality of nano light-emitting structures, respectively.

Each of the plurality of lenses may be arranged to correspond to two or more nano light emitting structures. Alternatively, each of the plurality of lenses may be arranged to correspond to one of the plurality of nano light emitting structures.

The nano light-emitting structure may include a main portion having a side surface that is a first crystal plane, and an upper end portion disposed on the main portion and having a surface that is a second crystal surface different from the first crystal surface.

In this case, the interface between the first light-transmitting portion and the second light-transmitting portion may be positioned substantially equal to or lower than the height of the main portion.

The contact electrode may be disposed on a side surface of the nano light-emitting structure such that at least a portion of the upper end of the nano light-emitting structure is exposed.

The second light-transmitting part may have an interface in direct contact with the surface of the nano light-emitting structure.

A third light-transmitting part may be disposed on the second light-transmitting part to provide an additional lens shape, and may further include a third light-transmitting part made of a material having a third refractive index different from the second refractive index.

An embodiment of the present invention provides a lighting device comprising a light emitting module having the above-described nanostructure semiconductor light emitting device, a driving unit configured to drive the light emitting module, and an external connection unit configured to supply an external voltage to the driving unit. can do.

By arranging layers having different refractive indices in different regions and arranging a plurality of lenses on the light extraction surface, it is possible to improve light extraction efficiency in a desired direction. By filling or emptying (air filling) a material having a relatively low refractive index between the nano light-emitting structures, light traveling in the lateral direction can be suppressed, thereby increasing light extraction efficiency. In addition, by introducing a lens structure made of a material having a relatively high refractive index in the upper direction, the light extraction efficiency toward the desired upper direction can be greatly improved.

1 is a schematic perspective view showing a nanostructure semiconductor light emitting device according to an embodiment of the present invention.
FIG. 2 is a side cross-sectional view showing the nanostructured semiconductor light emitting device shown in FIG. 1.
3A and 3B are cross-sectional views of a nano light emitting structure for explaining an effect of improving light extraction efficiency according to the embodiment shown in FIG. 1.
4 is a graph showing the change in light extraction efficiency according to the aspect ratio of the lens and the thickness of the plate.
5 is a plan view showing lenses of various shapes that can be employed in an embodiment of the present invention.
6A and 6B are side cross-sectional views showing lenses of various shapes that can be employed in an embodiment of the present invention.
7A to 7G are cross-sectional views illustrating a method of manufacturing the nanostructured semiconductor light emitting device shown in FIG. 1.
8A to 8E are cross-sectional views of major processes for explaining another example of a method of manufacturing a nanostructured semiconductor light emitting device.
9A and 9B are plan views of masks showing various examples of opening shapes.
10A and 10B are side cross-sectional views of a mask showing various examples of the shape of an opening.
11A and 11B are schematic diagrams for explaining a heat treatment process that can be applied in FIG. 8D.
12A to 12D are cross-sectional views for explaining a process for obtaining a nano core using the mask shown in FIG. 10A.
13 to 15 are cross-sectional views of nanostructured semiconductor light emitting devices according to various embodiments of the present invention (no plate).
16 to 20 are cross-sectional views of nanostructured semiconductor light emitting devices according to various embodiments of the present invention (partial contact electrodes are employed).
21 is a graph showing an effect of improving light extraction efficiency by employing a partial contact electrode.
22 to 24 are cross-sectional views of nanostructured semiconductor light emitting devices according to various embodiments of the present invention (spontaneous formation of lenses).
25 and 26 are cross-sectional views of a nanostructured semiconductor light emitting device according to various embodiments of the present invention (adopting an anti-reflective layer).
27 is a cross-sectional view of a nanostructured semiconductor light emitting device according to an embodiment (corrugated structure) of the present invention.
28 shows an example of a semiconductor light emitting device package employing a nanostructured semiconductor light emitting device according to an embodiment of the present invention.
29 and 30 show examples of a backlight unit employing a nanostructured semiconductor light emitting device according to an embodiment of the present invention.
31 shows an example of a lighting device employing a nanostructure semiconductor light emitting device according to an embodiment of the present invention.
32 shows an example of a headlamp employing a nanostructure semiconductor light emitting device according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

These embodiments may be modified in different forms or may be combined with each other, and the scope of the present invention is not limited to the embodiments described below. In addition, the present embodiments are provided to more completely explain the present invention to those with average knowledge in the art. For example, the shape and size of elements in the drawings may be exaggerated for clearer explanation, and elements indicated by the same reference numerals in the drawings are the same elements.

On the other hand, the expression "one example" used in the present specification does not mean the same embodiment, and is provided to emphasize and describe different unique features. However, the embodiments presented in the description below do not exclude that they are implemented in combination with features of other embodiments. For example, even if a matter described in a specific embodiment is not described in another embodiment, it may be understood as a description related to another embodiment unless a description contradicts or contradicts the matter in another embodiment.

1 is a schematic perspective view showing a nanostructure semiconductor light emitting device according to an embodiment of the present invention, and FIG. 2 is a side cross-sectional view showing the nanostructure semiconductor light emitting device shown in FIG. 1.

The nanostructure semiconductor light emitting device 100 illustrated in FIG. 1 may include a base layer 112 made of a first conductivity type semiconductor material and a plurality of nano light emitting structures 115 disposed thereon. In addition, the nanostructured semiconductor light emitting device 100 may include a substrate 111 having an upper surface on which the base layer 112 is disposed.

An unevenness R may be formed on the upper surface of the substrate 111. The irregularities R may improve the quality of a single crystal grown while improving light extraction efficiency. The substrate 111 may be an insulating, conductive, or semiconductor substrate. For example, the substrate 111 may be sapphire, SiC, Si, MgAl ₂ O ₄ , MgO, LiAlO ₂ , LiGaO ₂ , or GaN.

The base layer 112 may provide a growth surface of the nano light emitting structure 115. The base layer 112 _{may be a nitride semiconductor satisfying Al x} In _y Ga _{1 -x- y} N (0≤x<1, 0≤y<1, 0≤x+y<1), and a specific conductivity It can be doped with type impurities. For example, the base layer 112 may be doped with n-type impurities such as Si.

An insulating layer 113 having an opening for growing the nano light emitting structure 115 (especially, the nano core 115a) may be formed on the base layer 112. A nano core 115a may be formed in the area of the base layer 112 exposed by the opening. The insulating layer 113 may be used as a mask for growing the nano core 115a. For example, the insulating layer 113 may be an insulating material such as _{SiO 2} or SiN _x.

The nano light emitting structure 115 has a nano core 115a made of a first conductivity type semiconductor, an active layer 115b sequentially formed on the surface of the nano core 115a, and a second conductivity type semiconductor layer 115c. I can. _{The nano core 115a satisfies Al x} In _y Ga _{1 -x- y} N (0≤x<1, 0≤y<1, 0≤x+y<1) similar to the base layer 112 It may be a nitride semiconductor. For example, the nano core 115a may be n-type GaN. The active layer 115b may have a multiple quantum well (MQW) structure in which a quantum well layer and a quantum barrier layer are alternately stacked with each other. For example, in the case of a nitride semiconductor, it may have a multi-quantum well structure of GaN/InGaN. If necessary, the active layer 115b may have a single quantum well (SQW) structure. The second conductivity-type semiconductor layer 115c is _{a crystal satisfying p-type Al x} In _y Ga _{1 -xy} N (0≤x<1, 0≤y<1, 0≤x+y<1), and Accordingly, it may be composed of a plurality of layers.

The nano light emitting structure 115 employed in the present embodiment may include a main portion M having a hexagonal column structure and an upper end T positioned on the main portion M. The main part (M) of the nano light-emitting structure 115 has sides that are the same crystal plane, and the upper part (T) of the nano light-emitting structure 115 has a crystal plane different from that of the side surfaces of the nano light-emitting structure 115. I can. The upper end portion T of the nano light emitting structure 115 may have a hexagonal pyramid shape.

The nanostructured semiconductor light emitting device 100 may include a contact electrode 116 connected to the second conductivity type semiconductor layer 115c. The contact electrode 116 employed in this embodiment may be made of a transparent conductive material. Although not limited thereto, the contact electrode 116 may be either a transparent conductive oxide layer or a nitride layer in order to emit light toward the nano light emitting structure side (a direction opposite to the substrate side). For example, ITO (Indium Tin Oxide), ZITO (Zinc-doped Indium Tin Oxide), ZIO (Zinc Indium Oxide), GIO (Gallium Indium Oxide), ZTO (Zinc Tin Oxide), FTO (Fluorine-doped Tin Oxide), At least one selected from AZO (Aluminium-doped Zinc Oxide), GZO (Gallium-doped Zinc Oxide), In ₄ Sn ₃ O ₁₂ and Zn _(1-x) Mg _x O (Zinc Magnesium Oxide, 0≤x≤1) I can. If necessary, the contact electrode 116 may include graphene.

The nanostructured semiconductor light emitting device 100 may include first and second electrodes 119a and 119b. The first electrode 119a may be disposed in a region where a portion of the base layer 112 made of a first conductivity type semiconductor is exposed. In addition, the second electrode 119b may be disposed in a region where the contact electrode 116 is extended and exposed.

The nanostructure semiconductor light emitting device 100 may include a light-transmitting protective layer 117 formed on an upper surface of the nano light emitting structure 115. The light-transmitting protective layer 117 may serve as a passivation capable of protecting the nano light-emitting structure 115.

The light-transmitting protective layer 117 employed in this embodiment may be provided to improve light extraction efficiency suitable for the nano light-emitting structure 115.

As shown in FIG. 2, the light-transmitting protective layer 117 includes a first light-transmitting portion 117a made of a material having a first refractive index and a second transmission made of a material having a second refractive index greater than the first refractive index. It may include a miner (117b).

The first light-transmitting part 117a may be formed by filling a space between the plurality of nano light-emitting structures 115 with a material having the first refractive index. The first light-transmitting part 117a may be formed to have a thickness that does not cover part of the plurality of nano light-emitting structures 115.

The second light-transmitting part 117b may be disposed on the first light-transmitting part 117a to cover a part of the plurality of nano light-emitting structures 115. In this embodiment, the second light transmitting part 117b may include a plate P covering the nano light emitting structure 115 and a plurality of lenses L arranged on the plate P. In this embodiment, the plate P may be formed of a material having the same second refractive index as the plurality of lenses L, but is not limited thereto, and the plate P and the lens L are different from each other. It may be made of a material having a refractive index. For example, the lens L may have a refractive index greater than that of the plate P.

As shown in FIG. 1, four convex lenses L are arranged on the light-transmitting protective layer 117, and each of the lenses L corresponds to a region in which several nano light-emitting structures 115 are located. It can have a size. The lenses L may be spaced apart from each other to have a _{certain distance d 0.}

The light-transmitting protective layer 117 according to the present embodiment can effectively extract light in the upper direction.

Specifically, according to Snell's law, since light traveling to a region having a relatively low refractive index increases an incident angle range for total reflection, the amount of light traveling can be suppressed. On the other hand, since light traveling to a region having a relatively high refractive index has a small incidence angle range for total reflection, the amount of light traveling can be increased.

Therefore, when compared with the form in which the light-transmitting protective layer 117a' having a single refractive index is adopted (see Fig. 3A), the light-transmitting protective layer 117 employed in this embodiment (see Fig. 3B) is upwardly It can greatly increase the amount of light to be extracted. That is, as shown in FIG. 3B, by arranging the first light-transmitting portion 117a having a small refractive index in the space between the nano light-emitting structures 115 to reduce light traveling in the lateral direction of the nano light-emitting structure 115 ( A2→A2'), the second light-transmitting part 117b having a large refractive index may be disposed on the nano light-emitting structure 115 to greatly increase the amount of light that proceeds upward (A1→A1'). In addition, by arranging the lens L on the light emitting surface, it is possible to effectively extract the light A1". In this way, light propagation in the lateral direction of the nano light emitting structure 115 is suppressed and light is By effectively extracting, it is possible to greatly improve the light extraction efficiency in the desired upper direction.

In FIG. 3A, it is illustrated that the light-transmitting protective layer 117 having a single refractive index is formed of a material having a low refractive index, such as the first light-transmitting portion 117a, but has a high refractive index like the second light-transmitting portion 117b. It can be formed of a material. Even in this case, since the amount of light traveling in the lateral direction of the nano light-emitting structure 115 increases, light traveling in the upper direction of the nano light-emitting structure 115 is inevitably reduced compared to the structure of FIG. 3B.

In addition, it is possible to effectively extract light traveling in the upper direction by using the arrangement of the lenses L, and to implement a desired radiation pattern by adjusting the directivity angle using the shape and arrangement of the lenses L.

In order to examine the effect of the second light-transmitting part 117b employed in this embodiment, the change in light extraction efficiency according to _{the aspect ratio of the lens L and the thickness T 0 of the plate P was measured, and} The results are shown in the graph of FIG. 4. Here, the aspect ratio of the lens L is defined as the height h compared to the radius r of the lens L, as shown in FIG. 3B. The light extraction efficiency shown in FIG. 4 represents an improved value compared to the shape shown in FIG. 3A (a light-transmitting protective layer having a low refractive index is employed).

As shown in FIG. 4, it was found that the light extraction efficiency tends to increase as the aspect ratio of the lens R increases up to a certain level (eg, aspect ratio: about 0.9 or less). On the other hand, under constant aspect ratio conditions, the thickness (T ₀ ) of the plate P showed a rather decreasing tendency. For example, in the section where the thickness of the plate (T ₀ ) is about 1300 nm or less and the aspect ratio is about 0.5 or more, the light extraction efficiency can be improved by about 7%, and in the section indicated by the maximum value (Max), it is improved by 7% or more. You can expect the effect.

As described above, the nano light emitting structure 115 may include GaN (refractive index: about 2.4). In this case, the second refractive index (in the range of about 1.7 to about 3) of the second light-transmitting portion 117b disposed on the top is formed of a material having a range similar to the refractive index of the nano light-emitting structure 115, and The disposed first light transmitting part 117a may be formed of a material having a first refractive index (about 1.5 or less) lower than the second refractive index. In other words, the first refractive index may be smaller than the refractive index of the nano light emitting structure 115, and a difference between the first refractive index and the second refractive index may be 0.2 or more. In a specific example, the first light transmitting part 117a may be air not filled with another material layer.

In this way, in consideration of the refractive index of the nano light-emitting structure 115, it is possible to select the refractive index of the material constituting the first light-transmitting part 117a and the second light-transmitting part 117b. The refractive index is determined according to the refractive index of the first light-transmitting part 117a, but when the refractive index layer of the first light-transmitting part 117a is about 1.5 or less, the refractive index of the second light-transmitting part 117b may be about 1.7 or more. Also, as in the present embodiment, not only the plate P but also the lens L may be formed of the same material.

In order to improve the light extraction efficiency in the upper direction, the second light-transmitting part 117b is more similar to the refractive index of the nano light-emitting structure 115 than the first light-transmitting part 117a, or more than the nano light-emitting structure 115 It can have a high refractive index. For example, the second light transmitting part 117b is TiO ₂ (2.8), SiC (2.69), ZnO (2.1), ZrO ₂ (2.23), ZnS (2.66), SiN (2.05), HfO ₂ (1.95) And it may be at least one of the diamond (2.44) (refractive index (@450nm) in parentheses). In a specific example, when the nano light-emitting structure 115 is GaN (about 2.4), it may be 1.9 or more, preferably 2.0 or more.

As described above, by introducing the lens L together with a multilayer structure using different refractive indices, it is possible to effectively extract the light traveling in the upward direction, and the directivity angle can be adjusted using the shape and arrangement of the lens L. It can be adjusted, and the radiation pattern can be variously implemented using this. To this end, the lens employable in this embodiment can be variously modified.

5 shows a form in which lenses of various shapes that can be employed in the present embodiment are arranged on the upper surface of the nanostructured semiconductor light emitting device.

As shown in FIG. 5, the lens may be a circular plane (L1), an ellipse (L2), as well as a polygonal plane. For example, such a polygonal lens may be a square (L3), a parallelogram (L4), a hexagon (L5). In addition, as shown in L6, it may be a lens having various shapes.

6A and 6B are side cross-sectional views showing a convex lens employable in this embodiment. The convex lens L1 illustrated in FIG. 6A may have a shape in which the entire surface has a constant curvature. Alternatively, the convex lens L2 shown in FIG. 6B may have a convex shape having an upper plane. That is, the convex lens L2 shown in FIG. 6B may have a shape in which an upper portion of the convex lens shown in FIG. 6A is cut off.

As described above, the lens employable in the present embodiment may have various shapes. Here, the lens is exemplified in a form in which the lens has a size corresponding to a plurality of nano light-emitting structures NS, but is not limited thereto, and a lens corresponding to a single nano light-emitting structure may be provided (Figs. 14, 17, etc.). ).

7A to 7G are cross-sectional views illustrating a method of manufacturing the nanostructured semiconductor light emitting device shown in FIG. 1.

As shown in FIG. 7A, a plurality of nano cores 115a may be formed on the base layer 112 made of a first conductivity type semiconductor.

The substrate 111 may have an upper surface on which the irregularities R are formed. The base layer 112 may be formed on the upper surface of the substrate 111. An insulating film 113 having an opening O is formed on the base layer 112. A desired nano core 115a may be grown in the exposed area of the base layer 112 by using the insulating layer 113 as a mask.

In the present embodiment, the nano-core 115 formed using selective growth has been described, but unlike this, a method of growing a nano-core using a mold having an opening corresponding to the desired nano-core 117, and then removing the mold The desired nano core can be obtained.

As shown in FIG. 7B, an active layer 115b and a second conductivity type semiconductor layer 115c may be sequentially formed on the surfaces of the plurality of nano cores 115a.

Through this process, a plurality of desired nano light emitting structures 115 may be formed. The active layer 115b may have a multiple quantum well (MQW) structure in which a quantum well layer and a quantum barrier layer are alternately stacked with each other. For example, in the case of a nitride semiconductor, it may have a multi-quantum well structure of GaN/InGaN. If necessary, the active layer 115b may have a single quantum well (SQW) structure. The second conductivity-type semiconductor layer 115c is _{a crystal satisfying p-type Al x} In _y Ga _{1 -xy} N (0≤x<1, 0≤y<1, 0≤x+y<1), and Accordingly, it may be composed of a plurality of layers. For example, the second conductivity type semiconductor layer 115c may include an AlGaN electron blocking layer and a GaN contact layer.

Next, as shown in FIG. 7C, a contact electrode 116 may be formed on the nano light emitting structure 115.

The contact electrode 116 may be formed on the surface of the second conductivity type semiconductor layer 115c. Although not limited thereto, the contact electrode 116 employed in this embodiment may be made of a transparent conductive material. The contact electrode 116 may be either a transparent conductive oxide layer or a nitride layer. For example, it may be at least one selected from ITO, ZITO, ZIO, GIO, ZTO, FTO, AZO, GZO, In ₄ Sn ₃ O ₁₂ and Zn _(1-x) Mg _{x O.} If necessary, the contact electrode 116 may include graphene. A space may exist between the nano light emitting structures 115.

Subsequently, as shown in FIG. 7D, a first light-transmitting portion 117a may be formed to fill the space S between the nano light-emitting structures 115.

A material having a low refractive index such as _{SiO 2} (1.46) may be used for the first light transmitting part 117a. The first light transmitting part 117a may be formed by a deposition process such as a chemical vapor deposition process (CVD) or a physical vapor deposition process (PVD). Alternatively, a process different from a material that can be easily filled in the space between the nano light emitting structures 115 may be used. For example, the first light-transmitting part 117a may use TEOS (TetraEthylOrthoSilane), BPSG (BoroPhospho Silicate Glass), CVD-SiO ₂ , SOG (Spin-on Glass), SOD (Spin-on Delectric) materials. . In this case, since the fluidity of each material is used, the filling process can be easily performed by spin coating or reflow process.

Meanwhile, a light-transmitting resin having a relatively low refractive index (1.4 to 1.7) and excellent workability may also be used as the first light-transmitting portion 117a. For example, as the light-transmitting resin, at least one resin selected from epoxy resin, silicone resin, polyethylene, and polycarbonate may be used. The first light transmitting part 117a may employ a porous structure in order to implement a lower refractive index. For example, when porous silicon is used, a refractive index of about 1.2 can be achieved.

The first light-transmitting part 117a may have a thickness t1 smaller than the height of the nano-light-emitting structure 115 so that a part of the nano-light-emitting structure 115 is exposed. The exposed portion of the nano light-emitting structure 115 may be covered by a second light-transmitting portion to be formed in a subsequent process. The top surface of the first light-transmitting part 117a may be located at a point higher than 50% of the height H defined as the main part of the nano light-emitting structure 115.

Subsequently, as shown in FIG. 7E, a second light-transmitting portion 117b may be formed on the first light-transmitting portion 117a.

The second light-transmitting part 117b may be formed to cover the exposed area of the nano light-emitting structure 115 on the first light-transmitting part 117a. In this process, the thickness t2 of the second light transmitting part 117b may be formed in consideration of the desired height of the lens and the thickness of the plate. The second light transmitting part 117b may be formed to have a thickness equal to or greater than the sum of a desired lens height and a plate thickness.

The second light-transmitting part 117b may have an interface in direct contact with the nano light-emitting structure 115. As in this embodiment, a part of the second light-transmitting part 117b may be formed to fill the remaining space between the nano light-emitting structures 115. For example, it may be located in a partial area of the main part of the nano light emitting structure 115. By arranging the second light-transmitting part 117b in this way, more light may be extracted from the nano light-emitting structure 115 to the top through the second light-transmitting part 117b. The second light-transmitting part 117b may be formed such that a portion located in the main part of the nano light-emitting structure 115 has a predetermined thickness t3. This thickness t3 may be 50% or less of the height H defined as the main part of the nano light emitting structure 115. .

The second light transmitting part 117b may be formed by a deposition process such as a chemical vapor deposition process (CVD) or a physical vapor deposition process (PVD). The second light-transmitting part 117b has a higher refractive index than the first light-transmitting part 117a. The refractive index of the second light-transmitting part 117b is determined according to the refractive index of the first light-transmitting part 117a, but when the refractive index layer of the first light-transmitting part 117a is about 1.5 or less, the second light-transmitting part ( The refractive index of 117b) may be about 1.7 or more.

In order to improve light extraction efficiency in the upper direction, the second light-transmitting part 117b may have a refractive index similar to or higher than that of the nano light-emitting structure 115. For example, when the nano light-emitting structure 15 is GaN (about 2.4), it may be 1.9 or more, preferably 2.0 or more.

For example, the second light transmitting part 117b is TiO ₂ (2.8), SiC (2.69), ZnO (2.1), ZrO ₂ (2.23), ZnS (2.66), SiN (2.05), HfO ₂ (1.95) And it may be at least one of the diamond (2.44) (refractive index (@450nm) in parentheses). Under these conditions, the light extraction efficiency can be improved by about 5-7% compared to the light-transmitting protective layer having a single refractive index. In particular, when the first light-transmitting portion (first refractive index) is 1.5 or less than that of 2.0, a greater improvement effect can be expected.

When the ratio of the thickness t3 of the portion covering the main portion of the second light-transmitting portion 117b to the height H of the nano light-emitting structure 115 is increased to about 50%, the light extraction efficiency can be gradually improved. have. That is, the light extraction efficiency can be greatly improved by extending the second light-transmitting portion 117b to the main portion of the nano light-emitting structure 115 at an appropriate level (50% or less of the height of the main portion).

Next, a process of forming a plurality of lenses L arranged on the light emitting surface of the second light transmitting part 117b may be performed. The lens formation process according to the present embodiment may be implemented by a dry etching process using a photoresist pattern PR, as shown in FIGS. 7F and 7G.

First, as shown in FIG. 7F, a photoresist pattern PR having a desired lens shape is formed on the second light transmitting part 117b, and the second light transmitting part ( 117b) can be subjected to dry etching. The lens-shaped photoresist pattern PR can be obtained by forming a primary photoresist pattern using a lithography process, and then heat-treating the pattern to reflow.

In this dry etching process, as the photoresist pattern PR in the shape of a lens and the exposed area of the second light transmitting part 117b are etched together, as shown in FIG. 7G, the lens shape of the photoresist pattern PR It is transferred to the second light-transmitting portion 117b to form a desired lens (L).

The nanostructured semiconductor light emitting device according to the present embodiment can be manufactured by various manufacturing methods. 8A to 8E are examples of a method of manufacturing a nanostructured semiconductor light emitting device, illustrating a process of growing a nanocore by using a mask as a mold structure. This process may be understood as a process replacing the process of forming the nano light emitting structure shown in FIGS. 7A and 7B.

As shown in FIG. 8A, a base layer 132 may be provided by growing a first conductivity type semiconductor on the substrate 131.

The base layer 132 may provide a crystal growth surface for growing the nano light-emitting structure, and may be provided in a structure that electrically connects one end of the nano light-emitting structure 132 to each other. Accordingly, the base layer 132 may be formed of a semiconductor single crystal having electrical conductivity. When the base layer 132 is directly grown, the substrate 131 may be a substrate for crystal growth. _{A buffer layer composed of Al x} In _y Ga _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) on the substrate 131 before growth of the base layer 132 Including a multilayer structure may be additionally formed. The multilayer structure includes an undoped GaN layer and an AlGaN layer or an intermediate layer composed of a combination of these layers to prevent current leakage from the base layer 132 toward the buffer layer and improve the crystal quality of the base layer 132. .

Next, as shown in FIG. 8B, a mask 133 having a plurality of openings O and including an etch stop layer is formed on the base layer 132.

The mask 133 employed in this embodiment includes a first material layer 133a formed on the base layer 132 and a first material layer 133a formed on the first material layer 133a. A second material layer 133b having an etch rate greater than the etch rate may be included.

The first material layer 133a may be provided as the etch stop layer. That is, the first material layer 133a has an etching rate lower than that of the second material layer 133b under the etching condition of the second material layer 133b. At least the first material layer 133a is a material having electrical insulating properties, and if necessary, the second material layer 133b may also be an insulating material.

The first and second material layers 133a and 133b may be formed of different materials to obtain a desired difference in etch rate. For example, the first material layer 133a may be a SiN-based material, and the second material layer 133b may be _{SiO 2.} Alternatively, the difference in the etch rate may be implemented by using the pore density. The second material layer 133b or both the first and second material layers 133a and 133b may be formed of a material having a porous structure. When both the first and second material layers 133a and 133b are formed of a material having a porous structure, a difference in the etch rates of the first and second material layers 133a and 133b is secured by adjusting the difference in porosity. can do. In this case, the first and second material layers 133a and 133b may be formed of the same material. For example, the first material layer 133a is made of SiO ₂ having a first porosity, and the second material layer 133b is made of _{SiO 2 that} is the same as the first material layer 133a and has a second porosity, Here, it may have a second porosity greater than the first porosity. Accordingly, under the condition that the second material layer 133a is etched, the first material layer 133a may have an etch rate lower than that of the second material layer 133b.

The total thickness of the first and second material layers 133a and 133b may be designed in consideration of a desired height of the nano light-emitting structure. For example, the mask 133 may be formed to have a height equal to or greater than the height of the side surface of the nano core. In this embodiment, the etch stop level by the first material layer 133a may be designed in consideration of the total height of the mask 133 from the surface of the base layer 132. After the first and second material layers 133a and 133b are sequentially formed on the base layer 132, a plurality of openings O may be formed to expose the base layer 132 region. The formation of the opening (O) may be performed by forming a photoresist on the mask layer 133, and using the photoresist, and a wet/dry etching process using the same. The size of each opening O may be designed in consideration of the size of the desired nano light-emitting structure. For example, the opening O exposing the surface of the base layer 132 may be 600 nm or less of the width (diameter), and further 50 to 500 nm or less.

The opening O may be manufactured using a semiconductor process, and for example, an opening O having a high aspect ratio may be formed using a deep-etching process. The aspect ratio of the opening H may be 5:1 or more, and further 10:1 or more.

Although it may vary according to etching conditions, in general, the opening O in the first and second material layers 133a and 133b may have a width that decreases toward the base layer 132.

In general, a dry etching process is used for the deep etching process, and reactive ions generated from plasma may be used or an ion beam generated in a high vacuum may be used. Compared with wet etching, such dry etching can perform precise processing of microstructures without geometric limitations. A CF-based gas may be used for etching the oxide layer of the mask 133. For example, an etchant in which at least one _{of O 2} and Ar is combined with a gas such as _{CF 4} , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , and CHF _{3 may be used.}

The planar shape and arrangement of the openings O may be variously implemented. For example, in the case of a flat shape, it may be implemented in various ways such as a polygon, a square, an oval, and a circle. The mask 133 shown in FIG. 8B may have an array of openings O having a circular cross section, as shown in FIG. 9A, but may have different shapes and/or different arrangements as necessary. For example, as in the mask 133' shown in FIG. 9B, an array of openings O having a regular hexagonal cross section may be provided.

The opening O shown in FIG. 8B is illustrated as a rod structure having a constant diameter (or width), but is not limited thereto, and may have various structures using an appropriate etching process. As such an example, masks having openings of different shapes are shown in Figs. 10A and 10B. In the case of Fig. 10A, the mask 143 made of the first and second material layers 143a and 143b has an opening O of a column structure having a shape that increases in cross-sectional area as it goes upward, and in the case of Fig. 10B, The mask 143 ′ made of the first and second material layers 143a ′ and 143b ′ may have an opening O having a columnar structure whose cross-sectional area decreases toward the top.

Next, as shown in FIG. 8C, a plurality of nano cores 135a are formed by growing a first conductivity type semiconductor in the exposed area of the base layer 132 so that the plurality of openings O are filled. Then, a current blocking intermediate layer 134 is formed on the upper end portion T of the nano core 135a.

The first conductivity type semiconductor of the nano core 135a may be an n-type nitride semiconductor, and may be the same material as the first conductivity type semiconductor of the base layer 132. For example, the base layer 132 and the nano core 135a may be formed of n-type GaN.

The nitride single crystal constituting the nano core 135a may be formed using an MOCVD or MBE process, and the mask 133 acts as a mold of the nitride single crystal to be grown, thereby forming a nano core corresponding to the shape of the opening (O). (135a) can be provided. That is, the nitride single crystal is selectively grown in the region of the base layer 132 exposed to the opening O by the mask 133, filling the opening O, and the nitride single crystal to be filled is the opening ( It can have a shape corresponding to the shape of O).

A current blocking intermediate layer 134 is formed on the surface of the upper end portion T of the nano core 135a while leaving the mask 133 as it is. Accordingly, it is possible to easily form the current blocking intermediate layer 134 on a desired upper end without a separate mask forming process.

The current blocking intermediate layer 134 may be a semiconductor layer that is not intentionally doped or is doped with a second conductivity type impurity opposite to the nano core 135a. For example, when the nanocore 135a is n-type GaN, the current blocking intermediate layer 134 may be undoped GaN or GaN doped with p-type impurities such as Mg. In this case, the nano core 135a and the current blocking intermediate layer 134 can be continuously formed by switching only the types of impurities in the same growth process. In this way, the entire process may be further simplified by combining the forming process of the current blocking intermediate layer 134 and the molding process.

Subsequently, as shown in FIG. 8D, the mask 133 is removed up to the first material layer 133a as the etch stop layer so that the side surfaces of the plurality of nano cores 135a are partially exposed.

In this embodiment, by applying an etching process in which the second material layer 133b can be selectively removed, only the second material layer 133b may be removed and the first material layer 133a may remain. . The remaining first material layer 133a may prevent the active layer 135b and the second conductivity-type semiconductor layer 135c from being connected to the base layer 132 in a subsequent growth process.

As in this example, in the manufacturing process of the nano light-emitting structure using a mask having an opening as a mold, an additional heat treatment process may be introduced in order to improve crystallinity.

First, in order to improve the crystal quality of the nanocore during the growth of the nanocore 135a before the current blocking intermediate layer 134 is formed, a stabilization process (heat treatment process) of the nanocore 135a may be additionally performed. have. That is, when growing to the midpoint of the growth of the desired nanocore 135a (about 0.2 ~ 1.8㎛ height from the surface of the base layer 132), the supply of the TMGa source, which is a supply source of the group III element of GaN, is stopped, and in the NH ₃ atmosphere. Heat treatment may be performed for about 5 seconds to about 5 minutes at a temperature similar to the temperature of the substrate during growth (about 1000 to 1200°C).

In addition, after completing the growth of the nano-core 135a and removing the second material layer 133b of the mask, the surface of the nano-core 135a is heat-treated under certain conditions to cut the crystal plane of the nano-core 135a. It can be converted into a stable surface that is advantageous for crystal growth, such as a polar or non-polar crystal surface. This process can be described with reference to FIGS. 11A and 11B.

11A and 11B are schematic diagrams for explaining a heat treatment process that can be applied in the process of FIG. 8D.

Fig. 11A can be understood as the nanocore 135a obtained in Fig. 8D. The nano core 135a has a crystal plane determined according to the shape of the opening. Although different depending on the shape of the opening, in general, the surface of the nanocore 135a thus obtained has a relatively unstable crystal plane, and may not be a favorable condition for subsequent crystal growth.

As in the present embodiment, when the opening has a cylindrical rod shape, as shown in Fig. 11A, the side surface of the nano core 135a may have a curved surface other than a specific crystal surface.

When the nano-core 135a is heat-treated, unstable crystals on the surface thereof are rearranged, and as shown in FIG. 11B, a stable crystal plane such as semi-polar or non-polar may be obtained. The heat treatment conditions can be converted to a desired stable crystal plane by performing the heat treatment conditions at 600°C or higher, and in a specific example, 800 to 1200°C for several seconds to several tens of minutes (1 second to 60 minutes).

In this heat treatment process, if the substrate temperature is lower than 600°C, crystal growth and rearrangement of the nano-core are difficult, making it difficult to expect a heat treatment effect. If the temperature is higher than 1200°C, nitrogen (N) evaporates from the GaN crystal plane, resulting in deterioration in crystal quality . In addition, it is difficult to expect a sufficient heat treatment effect for a time shorter than 1 second, and heat treatment for a time longer than several tens of minutes, for example, 60 minutes may lower the efficiency of the manufacturing process.

For example, when grown on the C (0001) plane ((111) plane in the case of a silicon substrate) of the sapphire substrate, the cylindrical nano-core 135a shown in FIG. By heat treatment at, the curved surface (side surface), which is an unstable crystal surface, can be converted into a hexagonal crystal column (135a' in Fig. 11B) having a non-polar surface (m surface) that is a stable crystal surface. The stabilization process of such a crystal plane can be realized by a high-temperature heat treatment process.

This principle is difficult to clearly explain, but it can be understood that partial regrowth proceeds to have a stable crystal plane by depositing such residual source gas when crystals located on the surface are rearranged at high temperatures or when source gas remains in the chamber.

In particular, in terms of regrowth, the heat treatment process may be performed in an atmosphere in which the source gas remains in the chamber, or the heat treatment may be performed under conditions of intentionally supplying a small amount of source gas. For example, as shown in FIG. 11A, in the case of the MOCVD chamber, TMGa and NH ₃ remain, and by heat treatment in such a residual atmosphere, the source gas reacts on the surface of the nanocore and partial regrowth to have a stable crystal plane. Can be done. Due to this regrowth, the width of the heat-treated nano-core 135a' may be slightly larger than the width of the nano-core 135a before the heat treatment (see FIGS. 11A and 11B).

In this way, by introducing an additional heat treatment process, it may contribute to improving the crystallinity of the nanocore. That is, through such a heat treatment process, non-uniformities (eg, defects, etc.) existing on the surface of the nano-core after removing the mask can be removed, and stability of the crystal can be greatly improved through rearrangement of the internal crystals. . This heat treatment process may be performed under conditions similar to the growth process of the nano core in the chamber after removing the mask. For example, the heat treatment temperature (eg, the substrate temperature) may be performed between 800 to 1200° C., but a similar effect can be expected in a heat treatment process of 600° C. or higher.

Subsequently, as shown in FIG. 8E, an active layer 135b and a second conductivity type semiconductor layer 135c are sequentially grown on the surfaces of the plurality of nanocores 135a'.

Through this process, the nano light emitting structure 135 is composed of a first conductivity-type semiconductor nano-core (135a'), an active layer (135b) surrounding the nano-core (135a') and a second conductivity-type semiconductor layer (135b). It may have a core-shell structure including a shell layer.

The nano-core 135a' includes an upper end having a crystal plane different from its side surface, and as described above, the active layer formed on the upper end and the portion (II) of the second conductive type semiconductor layer include the active layer and the second conductive layer formed on the side surface. It may have a composition and/or thickness different from that of the portion (I) of the conductive type semiconductor layer. In order to solve the problem of leakage current and emission wavelength caused by this, the current blocking intermediate layer 134 is disposed on the upper end of the nano core 135a'. Due to the selective arrangement of the current blocking intermediate layer 134, the active layer region formed on the upper end of the nano core 135a ′ while ensuring the flow of current normally through the active layer region formed on the side of the nano core 135a ′. The flow of current through may be blocked by the current blocking intermediate layer 134.

Accordingly, it is possible to improve efficiency by suppressing leakage current concentrated on the upper end of the nano core 135a', and to accurately design a desired emission wavelength.

The mask employed in the above-described embodiment has exemplified a form composed of two material layers, but the present invention is not limited thereto, and may be implemented in a form employing three or more material layers.

For example, in the case of a mask having first to third material layers sequentially formed from the base layer, the second material layer is an etch stop layer and is made of a material different from the first and third material layers. If necessary, the first and third material layers may be made of the same material.

Since at least the second material layer has an etch rate lower than that of the third material layer under the etching condition of the third material layer, it may serve as an etch stop layer. At least the first material layer may be a material having electrical insulation, and if necessary, the second or third material layer may also be an insulation material.

12A to 12D are cross-sectional views for each major process illustrating a process of forming a nano light emitting structure using the mask 143 shown in FIG. 10A.

As shown in FIG. 12A, a nano core 145a may be grown on the base layer 142 by using the mask 143. The base layer 142 may be formed on the substrate 141. The mask 143 has an opening having a width that becomes narrower downward. The nano core 145a may be grown in a shape corresponding to the shape of the opening.

In order to further improve the crystal quality of the nano core 145a, one or more heat treatment processes may be introduced during growth. In particular, by rearranging the top surface of the nanocore 145a into a crystal plane of a hexagonal pyramid during growth, a more stable crystal structure can be obtained, and high quality of crystals to be grown afterwards can be ensured.

This heat treatment process may be performed under the temperature conditions described above. For example, it may be performed under a temperature condition that is the same as or similar to the growth temperature of the nano core 145a for the convenience of the process. In addition, it may be performed in a manner in which a metal source such as TMGa is stopped while maintaining a pressure/temperature equal to or similar to the growth pressure and temperature of the nano core 145a in an _{NH 3 atmosphere.} This heat treatment process may last for several seconds to tens of minutes (eg, 5 seconds to 30 minutes), but a sufficient effect can be obtained even with a duration of about 10 seconds to about 60 seconds.

In this way, the heat treatment process introduced in the process of growing the nano core 145a can prevent the deterioration of crystallinity caused when the nano core 145a is grown at a high speed, and thus, excellent crystal quality together with rapid crystal growth. I can plan.

The time and frequency of the heat treatment process section for stabilization may be variously changed according to the height and diameter of the final nano core. For example, if the width of the opening is 300 to 400 nm and the height (mask thickness) of the opening is about 2.0 μm, a stabilization time of about 10 seconds to about 60 seconds is inserted at the midpoint of about 1.0 μm to provide the desired high quality. Can grow its core. Of course, this stabilization process may be omitted depending on the core growth conditions.

Subsequently, as shown in FIG. 12B, a current blocking intermediate layer 144 may be formed on the upper end of the nano core 145a.

After forming the nano-core 145a to a desired height, a current blocking intermediate layer 144 may be formed on the upper surface of the nano-core 145a while leaving the mask 143 as it is. In this way, by using the mask 143 as it is, the current blocking intermediate layer 144 can be easily formed in a desired region (top surface) of the nano core 145a without a separate mask forming process.

The current blocking intermediate layer 144 may be a semiconductor layer that is not intentionally doped or is doped with a second conductivity type impurity opposite to the nano core 145a. For example, when the nanocore 145a is n-type GaN, the current blocking intermediate layer 144 may be undoped GaN or GaN doped with Mg, which is a p-type impurity. In this case, the nano core 145a and the current blocking intermediate layer 144 can be continuously formed by switching only the types of impurities in the same growth process. For example, if Si doping is stopped under the same conditions as the growth of the n-type GaN nanocore, and Mg is injected and grown for about 1 minute, the current blocking intermediate layer 144 having a thickness of about 200 nm to about 300 nm is formed. The current blocking intermediate layer 144 can effectively block a leakage current of several ㎂ or more. In this way, in the mold method process as in the present embodiment, the introduction process of the current blocking intermediate layer 144 may be simplified.

Subsequently, as shown in FIG. 12C, the mask 143 is removed up to the first material layer 143a, which is the etch stop layer, so that side surfaces of the plurality of nano cores 145a are exposed.

In this embodiment, by applying an etching process in which the second material layer 143b can be selectively removed, only the second material layer 143b may be removed and the first material layer 143a may remain. . The remaining first material layer 143a may prevent the active layer and the second conductivity-type semiconductor layer from being connected to the base layer 142 in a subsequent growth process.

As in the present embodiment, in the manufacturing process of the nano light emitting structure using the mask having an opening as a mold, an additional heat treatment process may be introduced to improve crystallinity.

After removing the second material layer 143b of the mask, the surface of the nanocore 145a is heat-treated under certain conditions to convert the unstable crystal plane of the nanocore 145a into a stable crystal plane (see FIGS. 11A and 11B). ). In particular, as in this embodiment, since the nano core 145a is grown in an opening having an inclined sidewall, it has a shape having an inclined sidewall corresponding to the shape, but as shown in FIG. 12D, after the heat treatment process The nano-core 145a' may have a substantially uniform diameter (or width) due to regrowth along with rearrangement of crystals. In addition, the upper end of the nanocore 145a immediately after growth may also have an incomplete hexagonal pyrimide shape, but the nanocore 145a' after the heat treatment process may be changed into a hexagonal pyramid shape having a uniform surface. In this way, after removing the mask, the nanocore having a non-uniform width may be regrown (and rearranged) into a hexagonal pyramidal column structure having a uniform width through a heat treatment process.

As described above, the nano light-emitting structure obtained by this process provides a desired nano-structure semiconductor light-emitting device through the processes of forming a cell structure, forming a contact electrode, forming a light-transmitting protective layer, and forming a lens as shown in FIGS. 7B to 7G. In addition, the light-transmitting protective layer (particularly, the second light-transmitting portion) employing a lens is not limited to the above-described embodiment and may be implemented in various structures. Various such embodiments are described throughout FIGS. 13-18 and 20-25.

13 is a cross-sectional view of a nanostructured semiconductor light emitting device according to an embodiment of the present invention.

The nanostructure semiconductor light emitting device shown in FIG. 13 is formed on a substrate 151 having an unevenness (R) and a base layer 152 made of a first conductivity type semiconductor material and disposed thereon. It may include a plurality of nano light emitting structures 155.

The nano core 155a may be formed in the area of the base layer 152 exposed by the opening of the insulating layer 153. The nano light emitting structure 155 has a nano core 155a made of a first conductivity type semiconductor, an active layer 155b sequentially formed on the surface of the nano core 155a, and a second conductivity type semiconductor layer 155c. I can.

The contact electrode 156 may be disposed on the surface of the nano light emitting structure 155 to connect to the second conductivity type semiconductor layer 155c. The contact electrode 156 employed in the present embodiment may be formed on almost the entire area of the second conductivity type semiconductor layer 155c.

The light-transmitting protective layer 157 may include a first light-transmitting part 157a made of a material having a first refractive index, and a second light-transmitting part 157b made of a material having a second refractive index greater than the first refractive index. I can. The first light-transmitting part 157a is filled in the space between the plurality of nano light-emitting structures 155, and the second light-transmitting part 157b is formed to cover the upper part of the plurality of nano light-emitting structures 155. I can.

The second light-transmitting portion 157b employed in the present embodiment may be formed of the lens L itself without a plate. The upper portion of the plurality of nano light emitting structures 155 may be directly covered by the lens R instead of a plate. Such a lens (L) is formed by dry etching using a photoresist pattern, as in the process described in FIGS. 7E and 7G, but by making the thickness t2 of the second light transmitting part relatively thin, there is no plate like this structure. A lens shape can be obtained.

Referring to FIG. 14, a light-transmitting protective layer 157' according to another example is shown. The light-transmitting protective layer 157 ′ includes a second light-transmitting portion 157b ′ providing a plurality of lenses L corresponding to each of the nano light-emitting structures 155. Each of the plurality of lenses L may have a convex shape while covering an upper portion of the nano light emitting structure 155. Since the second light-transmitting part 157b' employed in this embodiment also has a refractive index higher than that of the first light-transmitting part 157a, light generated from the nano light-emitting structure 155 is transmitted to the second light-transmitting part 157b. ') can be extracted more effectively.

15, a light-transmitting protective layer 157" according to another example is shown. Similar to FIG. 13, the light-transmitting protective layer 157" corresponds to a plurality of nano light-emitting structures 155. Although the lens L is provided, the lens may include an additional third light transmitting part 157c together with the second light transmitting part 157b". The second light transmitting part 157b" is shown in Fig. 6A. The third light transmitting part 157c is disposed on a flat upper surface of the second light transmitting part 157b" to have a convex shape. The second and third light transmitting parts 157b" and 157c" May be composed of two light-transmitting materials having different refractive indices. For example, the second light-transmitting part 157b" may have a refractive index greater than that of the first light-transmitting part 157a, but less than that of the third light-transmitting part 157c.

The lens L can be obtained by laminating two layers of light-transmitting material having different refractive indices and then dry etching using a photoresist pattern. This dry etching process can be understood with reference to the processes described in FIGS. 7E and 7G.

16 to 18 show examples of additionally improving light extraction efficiency by removing a partial region of a contact electrode.

Referring to FIG. 16, similar to the light-transmitting protective layer 157 shown in FIG. 13, the light-transmitting protective layer 167 is disposed on the first light-transmitting portion 167a and the first light-transmitting portion 167a. And a second light-transmitting part 167b made of a lens L covering the plurality of nano light-emitting structures 155. However, unlike the previous embodiments, the contact electrode 166 may be disposed in a region other than the upper end T of the nano light emitting structure 155 and a partial region of the side connected thereto.

Even if the contact electrode 166 is made of a transparent electrode material such as ITO, light loss may occur in the process of passing through the contact electrode 166, which is a factor that hinders light extraction efficiency.

In this embodiment, the light emitted from the upper region of the nano light-emitting structure 155 covered by the second light-transmitting part 167b does not pass through the contact electrode 166, but directly, the second light-transmitting part 167b, which is a high refractive index layer. ) Can enter, so it is possible to prevent light loss by the contact electrode 166. An effect of improving light extraction efficiency by partially removing the contact electrode may be described with reference to FIG. 21.

FIG. 21 is a graph comparing light extraction efficiency of a form E1 in which the contact electrode is deposited on the entire surface (E2) and a form in which the contact electrode is partially removed (E2).

Specifically, the graph shown in FIG. 21 shows the change in light extraction efficiency when increasing the refractive index n of the second light-transmitting part under the same condition in which the first light-transmitting part is formed _{of SiO 2 (refractive index: 1.46).} Here, the reference value (=100%) represents the light extraction efficiency measured in the form in which _{the first and second light transmitting portions are formed of SiO 2 in the same manner.}

Referring to FIG. 21, when the contact electrode is entirely deposited (E1), the light extraction efficiency is improved by up to 8%, whereas when the contact electrode is removed from the area in contact with the second light-transmitting part (E2), the light extraction efficiency. It can be seen that this improved to about 10% to about 12% (n is in the range of 1.8 to 2.2).

Meanwhile, in the embodiment shown in FIG. 16, as described in the previous embodiment, the portion t3 covering the main part by the second light transmitting part 167b is increased to an appropriate level (50% or less of the height of the main part). By doing so, the light extraction efficiency can be further improved.

In the selective removal of the contact electrode, the contact electrode is deposited to cover the entire surface of the nano light-emitting structure 155, and after forming the first light-transmitting part between the nano light-emitting structure 155, together with the first light-transmitting part. It can be obtained by etching back the contact electrode. Through this etch-back process, the first light-transmitting part 167a and the contact electrode 166 may have the same level, and the upper region of the nano light-emitting structure 155 disposed on the level may be exposed, Subsequently, the structure shown in FIG. 16 can be obtained by forming the second light-transmitting portion 167b.

Referring to FIG. 17, a light-transmitting protective layer 167' similar to that shown in FIG. 14 is shown. The light-transmitting protective layer 167 ′ includes a second light-transmitting portion 167b ′ providing a plurality of lenses L corresponding to each of the nano light-emitting structures 155. In this embodiment as well, the light emitted from the upper region of the nano light emitting structure 155 covered by the second light transmitting part 167b' does not pass through the contact electrode 166, but is directly transmitted through the second transmission layer, which is a high refractive index layer. Since the light unit 167b' can enter, light loss can be prevented by the contact electrode 166.

Referring to Fig. 18, a light-transmitting protective layer 167" similar to the embodiment shown in Fig. 1 is shown. A second light-transmitting portion 167b" of the light-transmitting protective layer 167" is a plate P. ) And a plurality of lenses disposed on the plate, and each lens has a structure corresponding to the plurality of nano light-emitting structures 155. Also in this embodiment, covered by the second light-transmitting part 167b" Since the light emitted from the upper region of the losing nano light-emitting structure 155 can directly enter the second light-transmitting portion 167b", which is a high refractive index layer, without passing through the contact electrode 166, the contact electrode 166 Thus, optical loss can be prevented.

The partially removed contact electrode may have various shapes. These various forms can be obtained by varying the partial removal process. For example, in the previous embodiment, the first light-transmitting layer and the contact electrode may be etched back together to partially remove the upper region of the contact electrode so as to have substantially the same level as the first light-transmitting layer. The contact electrode may be partially removed before the formation of, and in this case, the first light-transmitting layer may be formed at a different level. This embodiment is shown in Fig. 19.

Referring to FIG. 19, similar to the previous embodiments, the contact electrode 166 ′ is partially removed to expose the upper region of the nano light emitting structure 155, but unlike the forms shown in FIGS. 16 and 17, The contact electrode 166' and the first light-transmitting part 167a are illustrated in different levels. That is, as shown in FIG. 19, the contact electrode 166 ′ may have a level lower than the formation height of the first light-transmitting layer 167a. This structure can be obtained by partially removing the contact electrode 166 ′ before the first light transmitting part 167a is formed. In this process, unlike the present embodiment, the height of the first light-transmitting layer may be formed to be lower than the level of the partially removed contact electrode.

In addition, depending on the structure of the light transmitting layer and the method of forming the contact electrode, the partially removed contact electrode may have various arrangements. For example, a part of the light-transmitting layer may be applied before forming the contact electrode, and the remaining light-transmitting layer may be formed on the contact electrode. This example is shown in Fig. 20.

Referring to FIG. 20, similar to the embodiments shown in FIG. 19, the contact electrode 176 is partially removed so that the first light-transmitting portion 167a has different levels. Alternatively, the contact electrode 176 has a shape formed on a part of the light-transmitting layer (the first light-transmitting layer 197a). After the first light-transmitting layer 197a is formed, the contact electrode 176 is formed to perform a partial removal process of removing the upper region of the contact electrode 176, and a lens is placed on the partially removed contact electrode 176. The second light-transmitting layer 197b may be applied. In this embodiment, an additional light-transmitting layer 197c may be introduced before forming the second light-transmitting layer 197b. An area and a height in contact between the additional light-transmitting layer 197c and the nano light-emitting structure 155 may be appropriately designed. For example, it may be designed by appropriately adjusting factors such as the formation height of the first light-transmitting layer 197a and the removal area of the contact electrode 176.

In addition, the refractive index of the additional light transmitting layer 197c may be variously changed as necessary. For example, it may have an intermediate refractive index between the refractive index of the first light-transmitting layer 197a and the second light-transmitting layer 197b. I can.

22 to 24 show various examples of lenses that can be formed by a deposition process.

Referring to FIG. 22, the first light-transmitting portion 177a and the first light-transmitting portion 177a filled between the nano-light-emitting structures 155 are disposed so that the upper area of the nano-light-emitting structure 155 is exposed, A light-transmitting protective layer 177 including a second light-transmitting portion 177b covering the nano light-emitting structure 155 is shown. Unlike the previous embodiment, the second light-transmitting part 177b may be obtained by depositing a light-transmitting material having a high refractive index along the upper region of the nano light-emitting structure 175 and the surface of the first light-transmitting part 177a. .

In this embodiment, since the upper region of the nano light-emitting structure 155 has a protruding structure higher than the surface of the first light-transmitting part 177a, a material for the second light-transmitting part 177b is deposited to a substantially constant thickness. When configured, the second light transmitting part 177b may have a convex lens L1 structure at a position corresponding to the protruding structure. In addition, the second light-transmitting part 177b may include a plate P1 located on the surface of the first light-transmitting part 177a. The second light-transmitting part 177b thus obtained does not have a complete curved surface, but has a convex structure corresponding to the top of the protruding nano light-emitting structure, so it can function similar to a lens, and additional lithography and etch-back processes are not required. Therefore, a desired lens L1 can be obtained through a more simplified process.

Referring to FIG. 23, together with the first light-transmitting part 177a, a second light-transmitting part 177b' in contact with the upper area of the nano light-emitting structure 155 from which the contact electrode 166" is partially removed, and an additional A light-transmitting protective layer 177' having three light-transmitting portions 177c is shown.

Although the upper region of the nano light emitting structure 155 is exposed, the contact electrode 166" may have a higher level than the contact electrode 166" and the first light-transmitting part 177a, unlike the previous embodiments. In this form, the upper region of the contact electrode 166" is removed before the first light transmitting part 177a is formed, or the contact electrode 166" is formed after the first light transmitting part 176a is formed. The first light-transmitting part 176a is partially removed, but the etching condition can be obtained when the etching rate of the first light-transmitting part 176a is higher than that of the contact electrode 166".

The third light transmitting part 177c is disposed on the second light transmitting part 177b ′, and may have an additional lens structure. The refractive index of the first light-transmitting part 177a may be at least less than the refractive index of the nano light-emitting structure 155, and the refractive index of the second light-transmitting part 177b may be greater than the refractive index of the first light-transmitting part 177a. The refractive index of the third light transmitting part 177c may have a refractive index greater than that of the second light transmitting part 177b.

The lens L1 of the second light-transmitting part 177b is arranged to correspond to the individual nano light-emitting structure 155, whereas the lens L2 of the third light-transmitting part 177c is a plurality of nano light-emitting structures 155 It can be configured to correspond to. These complex lens structures L1 and L2 can provide various optical paths. The third light transmitting part 177c may have a plate P2 connecting the lens L2. The third light transmitting part 177c may be formed by the process shown in FIGS. 7F and 7G.

Referring to FIG. 24, first and second light transmitting portions 177a and 177b' similar to those of the example shown in FIG. 23 are provided, but the third light transmitting portion 177c' is an individual nano light emitting structure ( A light-transmitting protective layer 177" composed of a lens for 155 is shown.

25 and 26 are cross-sectional views of nanostructured semiconductor light emitting devices according to various embodiments of the present invention (adopting an anti-reflective film).

Referring to FIG. 25, a light-transmitting protective layer 187 similar to the structure shown in FIG. 18 is shown. The light-transmitting protective layer 187 includes a first light-transmitting portion 187a filled between the nano-light-emitting structure 155 and the nano-light-emitting structure 155 so that the upper region of the nano light-emitting structure 155 is exposed. And a second light-transmitting portion 187b having a plate P covering an upper region and a plurality of lenses L arranged on an upper surface of the plate P. An anti-reflective film 188 is coated on the surface of the second light transmitting part 187 to further improve light extraction efficiency.

Referring to FIG. 26, an example in which the non-reflective layer 188' is applied to the surface of the second light-transmitting portion 187b' having the lens L for the individual nano light emitting structure 155 is shown. The second light-transmitting part 187b ′ employed in the present exemplary embodiment may be disposed on the surface of the first light-transmitting part 187a and may have a plate P connecting the lens L.

27 is a cross-sectional view of a nanostructured semiconductor light emitting device according to an embodiment (corrugated structure) of the present invention.

Referring to FIG. 27, similar to the shape shown in FIGS. 1 and 2, light transmittance having a first light transmitting part 187a and a second light transmitting part 187b disposed on the first light transmitting part 187a. A protective layer 187 is shown. The second light transmitting part 187b may include a lens L related to the plurality of nano light emitting structures 155 and a plate P in which the lenses are arranged. The second light-transmitting portion 187b employed in this embodiment has a surface on which the irregularities C are formed. These irregularities (C) can be appropriately applied to all of the foregoing embodiments. In particular, it may be employed at the interface of layers having different refractive indices as well as the light emitting surface. For example, it may be introduced into the interface of the first and second light-transmitting portions or the second light-transmitting portion and the third light-transmitting portion.

As described above, the light-transmitting protective layer according to the present invention may be implemented in various forms, and the features presented in the various embodiments described above are combined with the features of different embodiments to constitute a new embodiment unless otherwise described. can do. For example, the current blocking intermediate layer 134 described in FIG. 8E may be employed in the nano light emitting structure of all the above-described embodiments to constitute a new embodiment. Embodiments based on these new combinations can also be said to fall within the scope of the present invention.

28 shows an example of a package employing the above-described nanostructured semiconductor light emitting device.

The semiconductor light emitting device package 600 illustrated in FIG. 28 may include the nanostructured semiconductor light emitting device 100, a mounting substrate 610, and an encapsulant 603 illustrated in FIG. 1.

The nanostructured semiconductor light emitting device 100 may be mounted on a mounting substrate 610 and electrically connected to the mounting substrate 610 through a wire W.

The mounting substrate 610 may include a substrate body 611, an upper electrode 613 and a lower electrode 614, and a through electrode 612 connecting the upper electrode 613 and the lower electrode 614. The mounting board 610 may be provided as a board such as a PCB, MCPCB, MPCB, or FPCB, and the structure of the mounting board 610 may be applied in various forms.

The encapsulant 603 may be formed in a dome-shaped lens structure with a convex top surface, but according to an embodiment, the direction of light emitted through the top surface of the encapsulant 603 is formed by forming the surface into a convex or concave lens structure. It is possible to adjust the angle. If necessary, a wavelength conversion material such as a phosphor or a quantum dot may be disposed on the surface of the encapsulant 603 or the nanostructured semiconductor light emitting device 100.

The nanostructured semiconductor light emitting device according to the above-described embodiment and a package including the same can be advantageously applied to various application products.

The nanostructured semiconductor light emitting device according to the above-described embodiment may be employed as a light source for various application products. 29 to 32 illustrate various application products in which a nanostructured semiconductor light emitting device can be employed.

29 and 30 show examples of a backlight unit employing a nanostructured semiconductor light emitting device according to an embodiment of the present invention.

Referring to FIG. 29, the backlight unit 1000 includes a light source 1001 mounted on a substrate 1002 and at least one optical sheet 1003 disposed thereon. The light source 1001 may use the above-described nanostructure semiconductor light emitting device or a package including the nanostructure semiconductor light emitting device.

Unlike the method in which the light source 1001 emits light toward the top of the liquid crystal display device in the backlight unit 1000 shown in FIG. 29, the backlight unit 2000 of the other example shown in FIG. 30 is a substrate 2002. The light source 2001 mounted thereon emits light in the lateral direction, and the emitted light is incident on the light guide plate 2003 to be converted into a surface light source. Light passing through the light guide plate 2003 is emitted upward, and a reflective layer 2004 may be disposed on the lower surface of the light guide plate 2003 to improve light extraction efficiency.

30 is an exploded perspective view showing an example of a lighting device employing a nanostructured semiconductor light emitting device according to an embodiment of the present invention.

The lighting device 3000 shown in FIG. 30 is shown as a bulb type lamp as an example, and includes a light emitting module 3003, a driving part 3008, and an external connection part 3010.

In addition, external structures such as the outer and inner housings 3006 and 3009 and the cover portion 3007 may be additionally included. The light emitting module 3003 may include a light source 3001, which may be the above-described nanostructure semiconductor light emitting device or a package including the nanostructure semiconductor light emitting device, and a circuit board 3002 on which the light source 3001 is mounted. . For example, the first and second electrodes of the nanostructured semiconductor light emitting device may be electrically connected to the electrode pattern of the circuit board 3002. In the present embodiment, one light source 3001 is illustrated as being mounted on the circuit board 3002, but a plurality of light sources 3001 may be mounted as necessary.

The outer housing 3006 may act as a heat dissipation unit, and includes a heat dissipation plate 3004 that directly contacts the light emitting module 3003 to improve a heat dissipation effect, and a heat dissipation fin 3005 surrounding the side of the lighting device 3000. I can. The cover part 3007 is mounted on the light emitting module 3003 and may have a convex lens shape. The driving unit 3008 may be mounted on the inner housing 3009 and connected to an external connection unit 3010 such as a socket structure to receive power from an external power source.

In addition, the driving unit 3008 serves to convert and provide an appropriate current source capable of driving the semiconductor light emitting device 3001 of the light emitting module 3003. For example, the driving unit 3008 may be composed of an AC-DC converter or a rectifier circuit component.

32 shows an example in which a nanostructure semiconductor light emitting device according to an embodiment of the present invention is applied to a head lamp.

Referring to FIG. 32, a headlamp 4000 used as a vehicle light, etc. includes a light source 4001, a reflective part 4005, and a lens cover part 4004, and the lens cover part 4004 is a hollow guide. It may include 4003 and a lens 4002. The light source 4001 may include the above-described nanostructure semiconductor light emitting device or a package including the nanostructure semiconductor light emitting device.

The head lamp 4000 may further include a heat dissipation unit 4012 that discharges heat generated from the light source 4001 to the outside, and the heat dissipation unit 4012 includes a heat sink 4010 and a cooling fan so that effective heat dissipation is performed. (4011) may be included. In addition, the headlamp 4000 may further include a housing 4009 that fixes and supports the heat dissipation part 4012 and the reflective part 4005. The housing 4009 may include a body portion 4006 and a central hole 4008 through which the heat dissipation portion 4012 is coupled to and mounted on one surface of the body portion 4006.

The housing 4009 may include a front hole 4007 that is integrally connected to the one surface and fixed to the other surface that is bent in a right angle direction so that the reflective part 4005 is positioned on the upper side of the light source 4001. Accordingly, the front side is opened by the reflector 4005, and the reflector 4005 is fixed to the housing 4009 so that the opened front corresponds to the front hole 4007 to reflect light reflected through the reflector 4005. It may pass through the front hole 4007 and be emitted to the outside.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have knowledge of

Claims (10)

A plurality of nano light-emitting structures each having a nano core made of a first conductivity type semiconductor, an active layer sequentially positioned on the surface of the nano core, and a second conductivity type semiconductor layer;
A contact electrode disposed on the surface of the second conductive semiconductor layer of the plurality of nano light emitting structures and made of a transparent conductive material;
A first light-transmitting part filled in the space between the plurality of nano light-emitting structures and made of a material having a first refractive index; And
A plurality of lenses disposed on the first light-transmitting part and each arranged to cover at least two nano light-emitting structures of the plurality of nano-light-emitting structures, and a material having a second refractive index greater than the first refractive index 2 Nano-structure semiconductor light emitting device including a light-transmitting portion.
The method of claim 1,
The second light-transmitting part further comprises a plate disposed on the first light-transmitting part to cover the plurality of nano light-emitting structures, wherein the plurality of lenses are arranged on the plate.
delete delete delete The method of claim 1,
The nano light-emitting structure is a nanostructure semiconductor light emitting device, characterized in that it comprises a main portion having a side surface as a first crystal plane, and an upper end portion having a surface that is a second crystal plane different from the first crystal plane on the main part.
The method of claim 6,
An interface of the first light-transmitting part and the second light-transmitting part is substantially equal to or lower than the height of the main part.
The method of claim 6,
The contact electrode is a nanostructure semiconductor light emitting device, characterized in that disposed on the side of the nano light emitting structure to expose at least a portion of the upper end of the nano light emitting structure.
The method of claim 8,
The nanostructure semiconductor light emitting device, characterized in that the second light-transmitting portion has an interface in direct contact with the surface of the nano-light emitting structure.
The method of claim 1,
A nanostructure semiconductor light emitting device further comprising a third light-transmitting part disposed on the second light-transmitting part to provide an additional lens shape, and comprising a third light-transmitting part made of a material having a third refractive index different from the second refractive index.

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