KR100658938B1 - Light emitting device with nano-rod and method for fabricating the same - Google Patents

Abstract

The present invention relates to a light emitting device having a nano-rod and a method of manufacturing the same, wherein the light emitting area of the device is increased by applying a structure in which light is emitted from a plurality of nanorod structures spaced apart from each other to increase light extraction efficiency. (Light extraction efficiency) has the effect of increasing.

In addition, it grows to nanorod size at low temperature, thereby relieving stress and strain due to lattice mismatch, and through penetration propagation to microscopic nanorods is reduced, thereby improving the crystallinity of the light emitting structure to improve device characteristics. It can be effective.

In addition, since the rod structures are spaced apart from each other, there is an effect that can reduce the scattering of light and improve the thermal characteristics inside the device.

Nano, rod, light emitting device, light extraction, light emission, area

Description

Light emitting device having nanorods and method of manufacturing the same {Light emitting device with nano-rod and method for fabricating the same}

1 is a cross-sectional view of a light emitting diode manufactured using gallium nitride according to the prior art.

2A to 2E are cross-sectional views for explaining a process of manufacturing a light emitting device having a nano-rod according to the present invention.

Figure 3 is a cross-sectional view for explaining the size of the nanorods according to the present invention

4A and 4B are schematic cross-sectional views illustrating a concept in which a nanorod is grown on a base substrate according to the present invention.

5 is a schematic cross-sectional view for explaining another method for manufacturing a light emitting device having a nanorod according to the present invention.

6 is a schematic cross-sectional view illustrating another method for manufacturing a light emitting device having a nanorod according to the present invention.

7 is a cross-sectional view illustrating a phenomenon in which light is emitted from a light emitting device having a nanorod according to the present invention.

<Description of the symbols for the main parts of the drawings>

300: base substrate 305: seed

307: buffer layer 310: nano-rod

320: active layer 330: compound semiconductor layer

350: light emitting structure 351: rod structure

400: electrode for ohmic contact and reflection 410: metal support

450: ohmic contact and transmission electrode

The present invention relates to a light emitting device having a nanorod and a method of manufacturing the same, and more particularly, to apply a structure in which light is emitted from a plurality of nanorod structures spaced apart from each other to increase the light emitting area of the device to increase light extraction efficiency ( The present invention relates to a light emitting device having nanorods capable of increasing light extraction efficiency and a method of manufacturing the same.

In general, light emitting devices such as light emitting diodes and laser diodes are single wavelength light sources having various applications such as backlights, signals, light sources, and full color displays.

Substances such as GaN and ZnO have a large energy bandgap of direct transition type. Recently, many researches and developments have been conducted and commercialized as light sources in the ultraviolet (UV), blue, and green wavelength ranges.

In the case of gallium nitride (GaN), many researches have been conducted on gallium nitride substrates, but there are many difficulties in implementing them, and since the price is high, the gallium nitride substrate is used for growing the structure of light emitting devices such as light emitting diodes and laser diodes. In addition, a substrate made of other materials such as silicon, sapphire and silicon carbide (SiC) is used.

1 is a cross-sectional view of a light emitting diode manufactured using gallium nitride according to the related art, and includes a buffer layer 110, an N-semiconductor layer 120, an active layer 130, and a P-semiconductor layer 140 on a substrate 100. ) Are formed sequentially; Mesa is etched from the P-semiconductor layer 140 to a portion of the N-semiconductor layer 120; A transparent electrode 150 and a P-electrode 170 are sequentially formed on the P-semiconductor layer 140; An N-electrode 160 is formed on the N-semiconductor layer 120 exposed by the mesa etching.

Such a light emitting diode is manufactured by growing a gallium nitride (GaN) -based material on a dissimilar substrate such as a sapphire substrate.Through dislocations, Many defects, such as TD) 180, are included in the growing film.

Al _1-x Ga _x N (0 <x≤1) grown at low temperature between the dissimilar substrate and the gallium nitride thin film when a gallium nitride material was grown on the dissimilar substrate by Shuji Nakamura of Japan in the 1990s. By inserting the layer, the density of defects can be reduced more than before (US005290393A).

Through this groundbreaking invention, many improvements have been made in the light emitting device characteristics such as gallium nitride (GaN) -based light emitting diodes and laser diodes, and commercialization has been made therefrom.

However, when the gallium nitride thin film is still grown using this method, a defect density of 10 ⁸ cm ⁻² or more is included in the thin film in the device structure, and further improvement is required.

In order to solve the problems as described above, the light extraction efficiency of the device may be increased by applying a structure in which light is emitted from a plurality of nanorod structures spaced apart from each other, thereby increasing light extraction efficiency. An object of the present invention is to provide a light emitting device having a nanorod and a method of manufacturing the same.

Another object of the present invention is to grow to a nano-rod size at a low temperature, to mitigate the stress and strain caused by lattice mismatch, and the penetration potential propagated to the fine nano-rods to reduce the crystallinity of the light emitting structure excellent growth of the device The present invention provides a light emitting device having a nanorod capable of improving characteristics and a method of manufacturing the same.

Still another object of the present invention is to provide a light emitting device having a nanorod that can reduce light scattering and improve thermal properties of the rod structure and spaced apart from each other, and a method of manufacturing the same.

A preferred aspect for achieving the above object of the present invention is a metal support;

An ohmic contact and reflection electrode formed on the metal support;

A plurality of nanorod structures formed on the ohmic contact and the reflective electrode and spaced apart from each other, wherein a compound semiconductor layer doped with a dopant of a first polarity and a compound semiconductor layer doped with an active layer and a dopant of a second polarity are sequentially formed. and;

Provided is a light emitting device having a nanorod including an ohmic contact and a transmissive electrode formed on the nanorod structure.

Another preferred aspect for achieving the above object of the present invention comprises the steps of: forming a plurality of nanorods made of a compound semiconductor doped with a dopant of a first polarity on the base substrate;

Sequentially forming a compound semiconductor layer doped with an active layer and a second polar dopant on each of the plurality of nanorods to form a plurality of rod structures spaced apart from each other;

Forming electrodes for ohmic contact and reflection on the rod structures;

Forming a metal support on the ohmic contact and reflection electrode;

Removing the base substrate from the rod structures;

Provided is a method of manufacturing a light emitting device having nanorods including forming ohmic contacts and transmissive electrodes under each of the exposed rod structures by removal of the base substrate.

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

2A through 2E are cross-sectional views illustrating a process of manufacturing a light emitting device having a nano-rod according to the present invention. First, a compound semiconductor doped with a dopant having a first polarity on an upper portion of a base substrate 300 is shown. To form a plurality of nanorods 310 made of (Fig. 2a).

Here, the base substrate 200 is a substrate, not a metal, and uses a substrate made of an oxide-based material such as Al ₂ O ₃ , Ga ₂ O ₃ , and a semiconductor material such as Si, SiC, GaAs.

In addition, as shown in FIG. 3, the nanorods 310 may have a width W of 1 to 1000 nm.

In addition, the nanorods 310 may include Al _x Ga _1-x N (0 ≦ _x ≦ 1), In _y Ga _1-y N (0 ≦ _y ≦ 1), and Zn _z Mg _1-z O (0 ≦ Preferably, they are single layer nanorods made of any one of z ≦ 1) and Zn _u Cd _1-u O (0 ≦ _u ≦ 1), or multilayer nanorods in which these materials are stacked.

In addition, the nanorods 310 are grown at a temperature of 200 ~ 900 ℃ using a crystal growth apparatus such as MOVPE, HVPE and MBE.

Therefore, when a compound semiconductor doped with a first polar dopant is grown on the base substrate 300, the plurality of nanorods 310, which are pillars having components perpendicular to the surface of the base substrate 300, are formed. Can be formed.

Thereafter, the plurality of rod structures 351 spaced apart from each other by sequentially forming an active layer 320 and a compound semiconductor layer layer 330 doped with a dopant of a second polarity on each of the plurality of nanorods 310. To form a light emitting structure 350 (FIG. 2B).

The compound semiconductor layer 330 doped with the active layer 320 and the second polar dopant are sequentially formed along the nanorods 310 to form a rod structure 351 spaced apart from each other.

That is, one rod structure 351 is grown independently without mutual interference with neighboring rod structures.

The active layer 320 is formed of multiple quantum wells.

Therefore, the light emitting structure 350 is formed of a plurality of rod structures including a compound semiconductor doped with a dopant having a first polarity, an active layer, and a compound semiconductor layer doped with a dopant having a second polarity.

Here, the dopant of the first polarity is either an N type dopant or a P type dopant, and the dopant of the second polarity is a dopant having a polarity opposite to that of the first polarity.

Therefore, since the first polar dopant has a polarity opposite to that of the second polar dopant, a nanorod made of a compound semiconductor doped with a second polar dopant may be formed on the base substrate 300.

For example, when the compound semiconductor layer doped with a dopant of a first polarity is N-GaN and the compound semiconductor layer doped with a dopant of a second polarity is P-GaN, the active layer alternately stacks InGaN and GaN. Multiple quantum wells with heterojunction can be formed.

Subsequently, an ohmic contact and reflection electrode 400 is formed on the rod structures 351, and a metal support 410 is formed on the ohmic contact and reflection electrode 400.

Here, the metal support part 410 is the electrode for ohmic contact and reflection using any one process of electrolytic plating, electroless plating, evaporation, sputtering and screen printing ( It is preferable that it is a layer formed on the upper layer 400 or an already made metal substrate bonded on the ohmic contact and reflective electrode 400.

And, the thickness of the metal support 410 is preferably 1 ~ 100㎛.

Subsequently, the base substrate 300 is removed from the rod structures 351 (FIG. 2D).

At this time, the base substrate 300 is removed by using a laser process, or by performing a wet etching process.

Finally, an ohmic contact and a transmission electrode 450 are formed under each of the rod structures 351 exposed by the removal of the base substrate 300 (FIG. 2E).

In this case, the ohmic contact and transmissive electrode 450 refers to a transparent electrode such as, for example, an IT0 film.

As a result, the manufacturing of the light emitting device having a nano-rod according to the present invention is completed.

That is, the light emitting device having the nanorods includes a metal support part 400; An ohmic contact and reflection electrode formed on the metal support part 400; A plurality of compound semiconductor layers formed on the ohmic contact and the reflective electrode 410 are spaced apart from each other, and a compound semiconductor layer doped with a dopant of a first polarity and a compound semiconductor layer doped with an active layer and a dopant of a second polarity are sequentially formed. Nanorod structures; An ohmic contact and a transmission electrode 450 formed on the nanorod structure are formed.

4A and 4B are schematic cross-sectional views illustrating a concept in which a nanorod is grown on a base substrate according to the present invention. As described above, the metal substrate may be formed at a 500 ° C. growth temperature within a temperature range of 200 to 900 ° C. FIG. When the compound semiconductor is grown on a non-base substrate, as shown in FIG. 4A, a plurality of seeds 305 are formed on the first base substrate 300 in a point shape.

Thereafter, if the component Gy, which is vertically grown than the component Gx, which is laterally grown on the seed 305, is predominantly dominated, each seed 305 is in a vertical direction than the volume grown in the horizontal direction. The growing volume is large, and a plurality of nanorods 310 spaced apart from each other are formed.

Here, the growth temperature of 500 ° C is a temperature relatively lower than the temperature for growing a compound semiconductor, such as GaN.

FIG. 5 is a schematic cross-sectional view illustrating another method of manufacturing a light emitting device having a nanorod according to the present invention. A buffer layer 307 is formed on a base substrate 300, and a buffer layer 307 is formed on the buffer layer 307. A plurality of nanorods 310 made of a compound semiconductor doped with a dopant of a first polarity is formed.

In this case, the plurality of nanorods 310 is grown at a temperature lower than the growth temperature of the buffer layer 307.

FIG. 6 is a schematic cross-sectional view illustrating another method for manufacturing a light emitting device having a nanorod according to the present invention, and includes a nanorod 310 and an active layer 320 made of a compound semiconductor doped with a dopant having a first polarity. ) And a plurality of rod structures 351 formed by sequentially forming the compound semiconductor layer 330 doped with the second polarity dopant are spaced apart from each other.

At this time, the second polarity of which the second polarity of the plurality of rod structures 351 is planarly sealed at a temperature higher than the growth temperature of the rod structure 351 on the compound semiconductor layer 330 doped with dopants of the second polarity The compound semiconductor layer 370 doped with the dopant is grown, and the ohmic contact and reflection electrode 400 is sequentially grown thereon.

Then, rather than forming the ohmic contact and reflective electrode 400 on the rod structure 351, the ohmic contact and the upper portion of the compound semiconductor layer 370 doped with the dopant of the second polarity which is sealed in the plane. It is easier to form the reflective electrode 400.

That is, since the rod structure 351 is in a discrete state in which a space exists between them, the electrode for ohmic contact and reflection on the compound semiconductor layer 370 doped with a doped dopant of a closed and planarized second polarity. 400 is more easily formed.

7 is a cross-sectional view illustrating a phenomenon in which light is emitted from a light emitting device having a nanorod according to the present invention. The nanorod 310, the active layer 320, and the first layer of the compound semiconductor doped with a dopant of a first polarity are formed. Since the rod structure 351 made of the compound semiconductor layer 330 doped with bipolar dopant is a light emitting structure, light is emitted from the active layer 320 of each rod structure 351.

Therefore, in the present invention, since light is emitted from a plurality of rod structures that are spaced apart from each other, there is an advantage in that the light emitting area is increased as compared with the area emitting light from the surface of the device as in the prior art.

In addition, since the rod structures are spaced apart from each other, there is an advantage that can reduce the scattering of light in the device, and improve the thermal characteristics.

Therefore, light extraction efficiency is increased.

In addition, when a gallium nitride thin film is grown on a dissimilar substrate, a defect called a threading dislocation having a density of 10 ⁸ to 10 ¹⁰ cm 2 is generated by lattice mismatch. While the defects in the device remain, the light emitting device with the nanorods of the present invention grows to nanorod size at low temperatures, thereby mitigating stress and strain due to lattice mismatch, and penetrating dislocations with extremely fine nanorods. It is possible to improve the characteristics of the device by reducing the propagation is excellent growth of the crystallinity of the light emitting structure.

As described above, the present invention has the effect of increasing the light extraction efficiency by increasing the light emitting area of the device by applying a structure in which light is emitted from a plurality of nano-rod structures spaced apart from each other. .

In addition, it grows to nanorod size at low temperature, thereby relieving stress and strain due to lattice mismatch, and through penetration propagation to microscopic nanorods is reduced, thereby improving the crystallinity of the light emitting structure to improve device characteristics. It can be effective.

In addition, since the rod structures are spaced apart from each other, there is an effect that can reduce the scattering of light and improve the thermal characteristics inside the device.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (14)

A metal support; An ohmic contact and reflection electrode formed on the metal support; A plurality of nanorod structures formed on the ohmic contact and the reflective electrode and spaced apart from each other, wherein a compound semiconductor layer doped with a dopant of a first polarity and a compound semiconductor layer doped with an active layer and a dopant of a second polarity are sequentially formed. and; A light emitting device having a nanorod including an ohmic contact and a transmission electrode formed on the nanorod structure. The method of claim 1, Between the nanorod structure and the electrode for ohmic contact and transmission, A light emitting device having a nanorod, further comprising a compound semiconductor layer doped with a dopant of a second polarity sealed in a plane. delete The method of claim 1, Wherein the dopant of the first polarity is an N type dopant or a P type dopant, and the dopant of the second polarity is a dopant having a polarity opposite to that of the first polarity. Forming a plurality of nanorods made of a compound semiconductor doped with a dopant of a first polarity on the base substrate; Sequentially forming a compound semiconductor layer doped with an active layer and a second polar dopant on each of the plurality of nanorods to form a plurality of rod structures spaced apart from each other; Forming electrodes for ohmic contact and reflection on the rod structures; Forming a metal support on the ohmic contact and reflection electrode; Removing the base substrate from the rod structures; Forming an electrode for ohmic contact and transmission under each of the rod structures exposed by the removal of the base substrate. The method of claim 5, The nanorods are a method of manufacturing a light emitting device having a nanorod, characterized in that for growing at a temperature of 200 ~ 900 ℃. The method of claim 5, Forming the nanorods, Forming a buffer layer on the base substrate, A method of manufacturing a light emitting device having nanorods, comprising: forming a plurality of nanorods formed of a compound semiconductor doped with a dopant of a first polarity on the buffer layer. The method of claim 7, wherein The plurality of nanorods, The method of manufacturing a light emitting device having a nanorod, characterized in that for growing at a temperature lower than the growth temperature of the buffer layer. The method of claim 5, Between removing the base substrate and forming the electrode for ohmic contact and transmission, Further growing a compound semiconductor layer doped with a second polar dopant in planar seal at a temperature higher than a growth temperature of the rod structure, on the compound semiconductor layer doped with the second polar dopant of the plurality of rod structures , A method of manufacturing a light emitting device having a nanorod, characterized in that an electrode for ohmic contact and reflection is formed on a compound semiconductor layer doped with a dopant of a second polarity sealed in a plane. The method of claim 5, The base substrate, Light emitting device having a nano-rod, characterized in that the substrate is not a metal. The method of claim 5, The nanorods are Al _x Ga _1-x N (0 ≦ _x ≦ 1), In _y Ga _1-y N (0 ≦ _y ≦ 1), Zn _z Mg _1-z O (0 ≦ _z ≦ 1) and Zn _u Cd _1-u O (0 ≦ _u ≦ 1) A method for manufacturing a light emitting device having nanorods, characterized in that they are monolayer nanorods made of any one material or multilayer nanorods in which these materials are stacked. . The method of claim 5, The metal support, A layer formed on the ohmic contact and reflective electrode using any one of electrolytic plating, electroless plating, evaporation, sputtering and screen printing, or Or a pre-made metal substrate bonded to the ohmic contact and reflective electrode. The method of claim 5, The thickness of the metal support is a manufacturing method of the light emitting device having a nanorod, characterized in that 1 ~ 100㎛. The method of claim 5, The base substrate, Method of manufacturing a light emitting device having a nano-rod, characterized in that to remove by performing a laser process or a wet etching process.

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