KR20120073508A - Contact-led using carbon wafer and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A contact type light emitting diode using a carbon wafer and a manufacturing method thereof are provided to improve productivity by preventing interface defects in a heterogeneous growth process of a semiconductor nano rod. CONSTITUTION: A transparent substrate(10) is made of transparent materials. A nano rod layer(30) is made of mono-atomic single crystal semiconductor and polyatomic single crystal compound semiconductor. The nano rod layer includes a plurality of semiconductor nano rods grown on the carbon wafer. A transparent electrode layer(20) is contacted with the semiconductor nano rod layer doped with a first polarity. A transparent semiconductor layer(21) is formed on the transparent electrode layer.

Description

Contact type light emitting diode using carbon wafer and manufacturing method thereof {Contact-LED using carbon wafer and Manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to nanorod type semiconductor devices, and more particularly, to a contact type light emitting diode using a carbon wafer and a method of manufacturing the same.

There is a lot of research to develop new optical devices using nanostructures of materials. Structures of several tens of nm in size, such as quantum dots, nanopowders, nanowires, nanotubes, quantum wells, and nanocomposites, exhibit optical, electrical, magnetic, and dielectric properties that are completely different from those of conventional thin films and bulks. . These characteristics have led to the development of devices to increase the efficiency of operation by applying low power, which is in line with the current generation development direction to save energy and conserve the environment.

Among the nanostructures, one-dimensional structures having high aspect ratios are called nanowires or nanorods, and many developments have been made in synthetic methods using various materials. Carbon nanotubes (CNT), cobalt silicides (CoSi), and the like are examples. In particular, when grown in a nanorod form rather than a thin film form, the advantages of high crystallinity and low dislocation density are also known. Carbon nanotube powder is already commercialized as a transparent electrode, a cathode component for field emission.

However, there is a problem that the nanorods are not easy to use because they are too small in size and weak in strength to be used for a functional device other than a transparent electrode. Efforts have been made to develop field effect transistors (FETs) by bonding metals to individual semiconductor nanorods and thermally treating them, and also growing semiconductor nanorods on dissimilar substrates, and then forming amorphous matrix materials such as silicon oxide or polyimide between semiconductor nanorods. Although the process of bonding the metal by making the top flat after filling is also developed, problems such as length uniformity of the nanorods are lowered and the light emitting surface is restricted. Devices containing nanorods need to be associated with a smooth subsequent process, such as electrode formation.

Zinc oxide (ZnO) nanorods among the materials applied to optoelectronic devices are promising materials capable of making optical devices in the ultraviolet (UV) and blue regions, but have a problem in that p-type doping is difficult due to their high self-compensation effect and crystallinity. A diode fabricated by heterogeneously growing an n-type zinc oxide nanorod layer on a p-type substrate of another semiconductor material does not emit light, and thus is used in a light-receiving element, or emits ultraviolet rays such as emitting light in green and infrared regions even when light is emitted. I can't. This is interpreted as many defects are formed at the growth interface during heterojunction.

In order to make functional devices using semiconductor nanorods with high chemical stability, high electrical properties, and high crystallinity, p-type doping problems should be solved, as in the case of zinc oxide, and when the p-type doping of nanorods is difficult, When bonding, the defects at the growth interface need to be removed, and subsequent processes after nanorod growth need to be solved.

The first technical problem to be achieved by the present invention is to provide a contact light emitting diode using a carbon wafer, which solves the problem of interfacial defects such as dislocations occurring during the heterogeneous growth of semiconductor nanorods, thereby facilitating ultraviolet light emission of the device. To provide.

The second technical problem of the present invention is to solve the problem of p-type doping in the development of functional devices using semiconductor nanorods, and to solve the problem of defects between interfaces occurring during heterogeneous growth of semiconductor nanorods. The present invention provides a method of manufacturing a contact type light emitting diode using a carbon wafer.

Contact type light emitting diode using a carbon wafer according to an embodiment of the present invention is a transparent substrate; A transparent electrode layer formed on the transparent substrate; Carbon wafers; A nanorod layer comprising a plurality of semiconductor nanorods doped with a first polarity and grown on the carbon wafer; And a second polarly doped transparent semiconductor layer formed on the transparent electrode layer and in physical contact with the ends of the semiconductor nanorods.

In addition, the method for manufacturing a contact type light emitting diode using a carbon wafer according to an embodiment of the present invention comprises the steps of forming a transparent electrode layer on a transparent substrate; Forming a transparent semiconductor layer doped with a second polarity on the transparent electrode layer; Growing a plurality of semiconductor nanorods doped with a first polarity on a carbon wafer to form a nanorod layer; Physically contacting ends of the semiconductor nanorods on the transparent electrode layer; And applying a predetermined pressure to the carbon wafer to fix the nanorod layer to the transparent semiconductor layer.

According to the embodiments of the present invention, while solving the p-type semiconductor doping problem while taking advantage of the nanostructure, and easy to emit ultraviolet light to induce light emission in the visible region using the light emitting device can be developed a simpler manufacturing process. .

1 illustrates a stacked structure of a contact type light emitting diode using a carbon wafer according to an embodiment of the present invention.
2A through 4 illustrate a process of manufacturing the semiconductor device of FIG. 1.
FIG. 5 shows an exemplary structure of a contact type light emitting diode including an active layer of a GaN / InGaN quantum well (QW) structure.
6 and 7 illustrate voltage-current characteristic diagrams of light emitting diodes manufactured according to the structure of FIG. 5.
8 illustrates an emission spectrum of an ultraviolet region of a light emitting diode manufactured according to the structure of FIG. 5.
<Description of Major Symbols in Drawing>
10: transparent substrate
20: transparent electrode layer
21: transparent semiconductor layer
30: semiconductor nanorod layer doped with first polarity
40: carbon wafer or metal wafer
50: contact surface of the semiconductor nanorod layer and the transparent semiconductor layer

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention illustrated below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

In the present invention, a transparent electrode layer is formed on the transparent substrate, a transparent semiconductor layer doped with a second polarity is formed on the transparent electrode layer, the nanorod layer doped with the first polarity is grown on a carbon wafer (or metal wafer), and the nano The rod layer includes a structure in which the transparent semiconductor layer is in contact. Since a carbon wafer or a metal wafer is an electrode layer with which current is easily applied, the semiconductor nanorods are grown on an electrode layer having excellent electrical conductivity. The voltage source is applied to the transparent semiconductor layer and the carbon wafer (or metal wafer).

Hereinafter, an example of using a carbon wafer will be described.

1 illustrates a stacked structure of a contact type light emitting diode using a carbon wafer according to an embodiment of the present invention.

The transparent substrate 10 is a basic substrate for growing the first polarized doped semiconductor nanorods and serves as a window for light emitted from the device or absorbed by the device. For example, the transparent substrate 10 may be one of glass, sapphire, and transparent plastic as a transparent material.

The transparent electrode layer 20 is an electrode contacting the semiconductor nanorod layer doped with the first polarity and serves as a window through which light enters or exits.

In the embodiments of the present invention, the base on which the nanorods grow is the carbon wafer 40. The first polarized doped semiconductor nanorods grown on the transparent electrode layer 20 are formed vertically or in a predetermined direction with respect to the transparent substrate 10. The length of the semiconductor nanorods is 0.3 um to 300 um. The width of the semiconductor nanorods is 10 nm to 1000 nm. The nanorod layer 30 may be formed of a monoatomic single crystal semiconductor, or a single crystal compound semiconductor of two or more atoms.

The transparent semiconductor layer 21 doped with the second polarity has a structure in place of the p-n type junction. In general, a semiconductor device is composed of a junction of a p-type and an n-type semiconductor. However, the p-n junction may be formed by a diffusion method by melting a semiconductor material or ion implantation of impurities, or by growing impurities by implanting impurities when forming a semiconductor thin film or bulk layer. However, at the interface 50 of FIG. 1, the transparent semiconductor layer 21 is only in contact with the upper portion of the nanorod layer 30, and any one of the constituent elements of the two materials is melted and joined by heat treatment or any manipulation. (Junction) or characterized in that the constituent materials do not diffuse with each other.

In FIG. 1, when the first polarly doped material is n-type, the second polarly doped material is p-type. On the contrary, when the first polarly doped material is p-type, the second polarly doped material is n-type. For n-type semiconductors, the doping concentration is preferably in the range of 1 × 10 ¹⁶ to 9 × 10 ²⁰ / cm ³ , and for p-type doped semiconductors, the doping concentration is in the range of 1 × 10 ¹⁷ to 9 × 10 ²⁰ / cm ^3. desirable.

When the nanorod layer 30 is an n-type doped semiconductor nanorod, and the material is not p-type doped, the use of the p-type doped semiconductor layer in the transparent semiconductor layer 21 solves the problem of p-type doping. The semiconductor nanorods have a high crystallinity and, among other things, an ideal p-n interface is formed when the tip of the nanorod having good crystallinity is in contact with the transparent semiconductor layer 21.

In one embodiment, a method of manufacturing a contact type light emitting diode using a carbon wafer includes forming a transparent electrode layer on a transparent substrate, forming a transparent semiconductor layer doped with a second polarity on the transparent electrode layer, and forming a transparent semiconductor layer on the carbon wafer. Growing a plurality of monopolar doped semiconductor nanorods to form a nanorod layer, physically contacting ends of the semiconductor nanorods on the transparent electrode layer, and applying a predetermined pressure to the carbon wafer to apply the nanorod layer to the semiconductor Fixing to the layer. Immediately before the growth of the nanorod layer 30, a buffer layer (not shown) for growing the nanorods on the carbon wafer 10 may be formed. Alternatively, the nanorod layer 30 may be grown directly on the carbon wafer 10. Hereinafter, a method of manufacturing a contact type light emitting diode using a carbon wafer according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 to 4b.

2A illustrates the transparent substrate 10 and the transparent electrode layer 20.

The transparent substrate 10 preferably uses a material having a higher melting point than the temperature at which the semiconductor nanorod layer is grown. For example, soda-lime or Corning-7059 products can be used for the transparent substrate 10.

Indium Tin Oxide (ITO), ZnO: Zn, ZnO: Ga, graphene, or the like may be used for the transparent electrode layer 20 formed on the transparent substrate 10. For example, ITO is coated on the transparent electrode layer 20 to a thickness of 800 kPa, so that a transparent electrode having a conductivity of 200 Ω / □ may be used.

When the transparent electrode layer 20 is formed on the transparent substrate 10, as shown in FIG. 2B, the transparent semiconductor layer 21 is formed on the transparent electrode layer 20.

FIG. 3A illustrates the growth of the nanorod layer 30 doped with the first polarity on the carbon wafer 40.

In the embodiments of the present invention, the growth base of the nanorods is not a semiconductor substrate, but a carbon wafer 40. The semiconductor nanorods of the nanorod layer 30 are preferably oriented at 90 ° with respect to the carbon wafer 40, but may be oriented in any direction with respect to the carbon wafer 40. When the nanorod layer 30 cannot be grown directly on the carbon wafer 40, a method using a metal or a method of forming a first polar nanorod layer after forming a homogeneous or heterogeneous buffer layer (not shown) You can also apply The nanorod layer 30 is a vapor phase transport process in which reaction atoms are transferred to a substrate and synthesized with a gas according to a material, and an organometallic chemical vapor deposition method in which an organometallic compound is grown on a substrate by synthesizing an organometallic compound with a reactant. (Metal-Organic source Chemical Vapor Deposition), sputtering (Sputter), can be grown using any one method of Chemical Electrolysis Deposition (Chemical Electrolysis Deposition). Since the semiconductor nanorods of the nanorod layer 30 should be longer than the diffusion distance of the charge carriers, the semiconductor nanorods should be 0.3 μm or more, and preferably smaller than 300 μm capable of uniform length growth. Since the semiconductor nanorods of the nanorod layer 30 tend to be inferior in crystallinity as the diameter increases, the semiconductor nanorods preferably have a diameter of 10 nm or more, and may have a diameter of up to 1,000 nm to maintain the crystallinity of the nanorods. The range of materials used in semiconductor nanorods is the width formed by the edges of the valence band and the conduction band, which form the forbidden energy band, which is explained by the band theory of the material crystal structure. refers to the range formed by (gap). The energy gap of a semiconductor varies from material to material. In the case of the detector element, when the wavelength of the light source to be excited is 100 nm, the band gap of the excited material may be 10 eV. Thus, the semiconductor range refers to a material having an energy band gap of 0.5-10 eV. Materials used for semiconductor nanorods include, for example, ZnO, ZnS, GaN, AlGaN, InGaN, and the like.

Figure 3b is a photograph of the zinc oxide nanorods grown in the same manner as above taken with an electron microscope. As can be seen in the photograph, it can be seen that the nanorods of the hexagonal structure are very well formed.

3C is a photograph of a cross section of the nanorods using an electron microscope after growing a zinc oxide nanorod layer on a carbon wafer. As can be seen from the photograph, it can be seen that the nanorods of hexagonal structure are aligned very well vertically.

4 illustrates the carbon wafer 40 and the nanorod layer 30 mounted on the transparent semiconductor layer 21.

The carbon wafer 40 and the nanorod layer 30 are fixed to the transparent semiconductor layer 21 while applying an appropriate pressure to the carbon wafer 40 in a pressure range of 0.05 N / cm ² to 8 N / cm ² . The pressure at which the nanorod layer 30 is compressed with the transparent semiconductor layer 21 may be determined according to the shape of the semiconductor nanorod. Experimentally, when applying a pressure of 8 N / cm ² or more, the commutation characteristics of the device disappeared regardless of the shape of the nanorod layer 30.

The curved ends of the semiconductor nanorods maintain constant contact with the transparent semiconductor layer 21. Fixing the nanorod layer 30 may use an epoxy. In particular, it is preferable to use an epoxy that can withstand 300 ° C. in order to prepare for the subsequent metal treatment process.

In another embodiment of the inventive concept, a heat dissipation layer may be formed in the semiconductor device of FIG. 1. When the semiconductor device according to an embodiment of the present disclosure operates at 10V or more, a lot of heat may be generated. A heat dissipation layer attached to the top surface of the carbon wafer 40 may help to cool this heat.

5 shows an exemplary structure of a contact light emitting diode having n-ZnO nanorods, p-GaN, InGaN / GaN (quantum wells), and n-GaN structures. In FIG. 5, InGaN / GaN, n-GaN, u-GaN, and the like layers determine the wavelength (or color) of light that the diode can emit. In a blue LED, an InGaN / GaN multi-quantum well structure may be used. In a UV LED, a GaN / AlGaN, InAlGaN / InAlGaN, InGaN / AlGaN multi-quantum well structure may be used. The materials used in FIG. 5 are merely exemplary, and embodiments of the present invention are not limited thereto.

FIG. 6 is a graph illustrating a result of measuring an I-V curve of a contact type light emitting diode having a structure as shown in FIG. 5 at an applied voltage of −18V to + 18V. As can be seen from the graph, it shows general pn diode characteristics, and when the voltage is applied in the forward direction, the current starts to flow from about 3V, and the current increases almost linearly to 18V, and very high current flows up to about 220mA. It can be seen that.

FIG. 7 is a graph of light emission intensity measured by a radiometer (CS-100A, Konica Minolta, Japan) according to an applied voltage of a contact type light emitting diode having a structure as shown in FIG. 5. It can be seen that when the forward voltage of the diode is applied, the emission intensity increases almost linearly and increases to about 4500 cd / m ² at about 18V.

8 is an EL (Electro-Luminescence) spectrum of a contact type light emitting device having the structure as shown in FIG. 5. This spectrum was measured using a Si-diode array sensor. The peak position of the EL spectrum was observed at 471.2 nm at low voltage, and it showed that the peak position shifted to the long wavelength region by about 3 nm as 474.2 nm when the applied voltage increased to 18V.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and variations may be made therefrom. And, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (17)

A transparent substrate;
A transparent electrode layer formed on the transparent substrate;
Carbon wafers;
A nanorod layer comprising a plurality of semiconductor nanorods doped with a first polarity and grown on the carbon wafer; And
And a second polarized doped transparent semiconductor layer formed on the transparent electrode layer and in physical contact with the ends of the semiconductor nanorods. The method of claim 1,
And when the semiconductor nanorods are doped with an n-type, the transparent semiconductor layer is doped with a p-type. The method of claim 1,
And when the semiconductor nanorods are doped with a p-type, the transparent semiconductor layer is doped with an n-type. The method of claim 1,
And the semiconductor nanorods are vertically oriented with respect to the transparent substrate. The method of claim 1,
And the semiconductor nanorods are grown at an angle not perpendicular to the transparent substrate. The method of claim 1,
The nanorod layer is either a monoatomic single crystal semiconductor or a polyatomic single crystal compound semiconductor, characterized in that the contact type light emitting diode using a carbon wafer. The method of claim 1,
The semiconductor nanorods have a height of 0.3 μm to 300 μm and a diameter of 10 nm to 1,000 nm, the contact light emitting diode using a carbon wafer. The method of claim 1,
The transparent semiconductor layer
A contact type light emitting diode using a carbon wafer, which is a p-GaN layer. The method of claim 1,
The transparent electrode layer is a contact type light emitting diode using a carbon wafer, characterized in that it comprises an active layer of quantum well structure. Forming a transparent electrode layer on the transparent substrate;
Forming a transparent semiconductor layer doped with a second polarity on the transparent electrode layer;
Growing a plurality of semiconductor nanorods doped with a first polarity on a carbon wafer to form a nanorod layer;
Physically contacting ends of the semiconductor nanorods on the transparent electrode layer; And
And applying a predetermined pressure to the carbon wafer to fix the nanorod layer to the transparent semiconductor layer. 11. The method of claim 10,
The nanorod layer is either a monoatomic single crystal semiconductor or a polyatomic single crystal compound semiconductor, characterized in that the contact type light emitting diode manufacturing method using a carbon wafer. 11. The method of claim 10,
Forming the nanorod layer is
And growing the semiconductor nanorods using a catalyst method. 11. The method of claim 10,
Forming the nanorod layer is
Forming a buffer layer on the carbon wafer and growing the semiconductor nanorods, characterized in that the contact type light emitting diode manufacturing method using a carbon wafer. 11. The method of claim 10,
Forming the nanorod layer is
The semiconductor nanorods are grown by any one of a vapor phase transport process, a metal-organic source chemical vapor deposition, a sputtering method, and a chemical electrolysis deposition method. Method of manufacturing a contact type light emitting diode using a carbon wafer, characterized in that the step. 11. The method of claim 10,
The transparent semiconductor layer
A method of manufacturing a contact type light emitting diode using a carbon wafer, characterized in that it is a p-GaN layer. 11. The method of claim 10,
Fixing the nanorod layer to the transparent semiconductor layer
Method of manufacturing a contact type light emitting diode using a carbon wafer, characterized in that the step of applying a pressure of 0.05 to 8 N / cm ² to the carbon wafer. 11. The method of claim 10,
Fixing the nanorod layer to the transparent semiconductor layer
And attaching an epoxy that connects the side surface of the carbon wafer, the transparent electrode layer, and the side surface of the transparent substrate while applying pressure to the carbon wafer. .

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