KR100693129B1 - Method for fabricating single-rod GaN pn junction LED - Google Patents

Abstract

In the pn-junction GaN nanorod LED manufacturing method according to the present invention, the n-type (220a) is a GaClx gas and NH3 gas is supplied into the reactor loaded with the growth substrate 10 is loaded these gases in the temperature range of 400 to 600 ℃ P-type (220b) is grown on the growth substrate (10) by supplying GaClx gas, NH3 gas, and acceptor-containing gas into the reactor to grow by reacting these gases in the temperature range of 400 to 600 ℃ Forming a pn junction nanorod in the; Cutting pn-bonded GaN nanorods formed on the growth substrate 10; And forming metal electrodes 30a and 30b in ohmic contact with the p-type and n-type regions, respectively, on the cut pn junction GaN nanorods.

Nanorod, GaN, GaClx, NH3, HVPE, Mg, pn junction, LED, ohmic contact,

Description

Method for fabricating single-rod GaN pn junction LED             

1 is a cross-sectional view illustrating a method for forming a pn junction GaN nanorod according to the present invention;

2 is a cross-sectional view for explaining a conventional GaN thin film growth mechanism;

3 is a cross-sectional view illustrating a GaN nanorod growth mechanism according to the present invention;

FIG. 4 is a SEM photograph actually showing the growth mechanism of FIG. 3.

5 is a schematic diagram illustrating a method of completing an LED according to the present invention;

Figure 6 is a view showing the electrical and optical properties of the pn junction GaN nanorods LED prepared according to the present invention.

<Description of Reference Numbers for Main Parts of Drawings>

10: substrate for growth 20: GaN thin film

30a, 30b: metal electrode 110: LED substrate

120: GaN nanorod 20a, 120a: GaN seed

220a: n-GaN nanorod 220b: p-GaN nanorod

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a light emitting diode (LED), and more particularly, to a method of manufacturing an LED using a pn-bonded GaN nanorod formed by a hybrid vapor phase epitaxial growth (HVPE) method. .

Today, remarkable developments in information and communication civilization are based on silicon semiconductors. The semiconductor is a very important field not only in terms of science and technology but also in a large market worldwide. However, as the principle limits in the development of silicon semiconductors are approached, the world is turning to next-generation semiconductors as technology diversifies from the dependence of silicon semiconductors. A compound semiconductor capable of simultaneously controlling electrons and electrons.

An example of such a compound semiconductor is GaN. GaN is a nitride semiconductor with a Wurzite structure, and has a direct transition bandgap of 3.4 eV corresponding to the blue wavelength band of visible light at room temperature. Because of the characteristics of the direct-transition semiconductor within the entire composition range of the electroluminescent solid, it is the most popular blue light emitting and light emitting device material.

Some research has been done on how to grow GaN into thin films, but the research is in its infancy, despite the many potential benefits of growing it to nanorods.

Accordingly, a technical problem of the present invention is to grow a GaN nanorods using the HVPE method, but the pn junction GaN nanorods LED manufacturing method of making an LED having one nanorod by forming a pn junction on each of the nanorods To provide.

Pn-junction GaN nano-rod LED production method according to the present invention for achieving the above technical problem, n-type GaClx gas and NH3 gas is supplied into the reactor in which the growth substrate is loaded these gases are 400 to 600 ℃ temperature range Pn-junction nanoparticles on the growth substrate by growing at a temperature of 400-600 ° C. by supplying GaClx gas, NH3 gas, and acceptor-containing gas into the reactor. Forming the rod for 30 minutes to 10 hours; Cutting the pn junction GaN nanorods formed on the growth substrate; And forming a metal electrode in ohmic contact with the p-type and n-type regions, respectively, on the cut pn junction GaN nanorod.

The forming of the metal electrode may include: laying the cut-out pn-bonded GaN nanorod on a LED substrate; And depositing the metal electrodes on the substrate for the LEDs to cover both ends of the pn junction GaN nanorods, respectively. Here, the surface of the LED substrate on which the pn-bonded GaN nanorods are laid down is preferably made of an insulator.

Ni / Au electrodes may be used as the metal electrodes in ohmic contact with the p-type, and Ti / Al electrodes may be used as the metal electrodes in ohmic contact with the n-type.

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

[Pn Junction GaN Nanorod Formation]

Methods of growing an epilayer include a large phase phase epitaxial growth (VPE), a liquid phase epitaxial growth (LPE), and a solid phase epitaxial growth (SPE). Here, the VPE is to grow crystals on the substrate through decomposition and reaction by heat while flowing the reaction gas on the substrate, depending on the raw material of the reaction gas, hydride VPE (HVPE), halide VPE (halide VPE), organic Metal organic VPE (MOVPE).

The present invention uses the HVPE (hydride VPE) method. Specifically, referring to FIG. 1, first, GaClx gas and NH3 gas are flowed into an HVPE reactor (not shown) in which the growth substrate 10 is loaded, and the temperature of the growth substrate 10 is 400 to. When the temperature is 600 ° C, the GaClx gas and the NH3 gas react with each other to form the n-GaN nanorod 220a on the growth substrate 10 by itself.

GaN grown without artificial doping is already known to have n-type properties basically due to nitrogen vacancies or oxygen impurities. Of course, an n-type may be formed by doping a donor such as Si.

When the n-GaN nanorods 220a are grown to some extent after an appropriate growth time, such as between 30 minutes and 5 hours, a gas containing an acceptor, e.g., Mg, is added to the HVPE reactor together with the GaClx gas and NH3 gas. Feed to continue the reaction. Then, the acceptor is doped in-situ on the GaN nanorods to form the p-GaN nanorods 220b so that a pn junction is formed on one nanorod. The p-GaN nanorods 220b may also be grown for 30 minutes to 5 hours.

The growth temperature of the p-GaN nanorod 220b does not need to be different from that of the n-GaN nanorod 220a. As the acceptor is doped in-situ with the growth of the p-GaN nanorod 220b, the acceptor is uniformly distributed in the longitudinal direction of the GaN nanorod without any special post-treatment.

In FIG. 1, an n-type is grown first and then a p-type is grown, but vice versa can be implemented by changing the above-described order. That is, the n-type may be grown first, and then p-type may be grown on the n-type by supplying an acceptor-containing gas in addition to the GaClx gas and NH3 gas supplied during the n-type growth, and vice versa. In the p-type growth, only the acceptor-containing gas may be blocked and the GaClx gas and the NH3 gas may be continuously supplied as it is to grow the n-type on the p-type.

The GaClx gas may be obtained by, for example, reacting Ga metal and HCl gas with each other at a temperature range of 600 to 900 ° C, such as 750 ° C. As the acceptor-containing gas, Cp 2 Mg (CycloPenta-Dienyl Magnesium) gas or MgCl gas may be used, and the MgCl gas may be obtained by, for example, reacting Mg metal and HCl gas at 600 to 900 ° C.

If the temperature of the growth substrate 10 is raised to about 1050 ° C., the GaN seed layer 20a is formed as shown in FIG. 2, and then they are immediately grown upward and sideways as indicated by reference numerals 20b and 20c. As a result, a GaN thin film 20 is formed on the growth substrate 10.

However, when the substrate temperature is lowered to about 400 to 600 ° C as in the present invention, the GaN seed layer 120a is formed as shown in FIG. As it does not grow much, the GaN nanorods 120 are formed.

As shown in FIG. 2, when GaN is deposited at a high temperature, GaN thin films 20 are formed by immediately growing sideways before the GaN rods 20b and 20c grow to some extent. This process is so instantaneous that it is virtually impossible to control GaN to nanorods in time. However, when GaN is deposited at a low temperature as in the present invention, it is possible to control the growth of GaN with time.

According to the present invention, the growth substrate 10 may be sapphire, silicon, or any kind thereof, regardless of the presence of a catalyst or template layer.

FIG. 4 is an SEM image showing the growth mechanism of FIG. 3, showing how a GaN nanorod is formed on a sapphire substrate over time at 480 ° C. without the aid of a catalyst or template layer. In the figure, the scale bar size is 10 nm for 10 minutes, 200 nm for 20 minutes, and 500 nm for 1 hour.

Referring to Figure 4, when grown for 1 hour, the nanorods can be seen that the diameter is about 80 ~ 120 nm and very uniformly distributed. If the growth times are the same, the diameter of the nanorods will vary with the growth temperature.

[LED manufacturing]

5 is a schematic view for explaining a method of completing an LED according to the present invention.

First, according to the method as shown in FIG. 1, a plurality of pn-bonded GaN nanorods are grown on the growth substrate 10 uniformly at a high density, and any one of these nanorods is cut out to form the LED substrate 110. Lay on your stomach. Here, the surface of the LED substrate 110 on which the GaN nanorods are placed is preferably made of an insulator. In FIG. 5, a silicon substrate having silicon oxide formed on its surface is taken as an example.

In addition, the metal substrates 30a and 30b are formed on the LED substrate 110 using an arbitrary deposition method, wherein the metal electrodes 30a and 30b are deposited to cover both ends of the pn junction GaN nanorods, respectively. Should be.

As the material of the metal electrodes 30a and 30b, it is preferable to adopt ohmic contact with the p-GaN 220b and the n-GaN 220a, respectively. As the metal electrode 30b that is in ohmic contact with the p-GaN 220b, a Ni / Au electrode in which Ni is first deposited on the p-GaN 220b and Au is deposited on the p-GaN 220b may be used. As the metal electrode 30a in ohmic contact with 220a, Ti / Al electrode may be used in which Ti is first deposited on n-GaN 220a and Al is deposited thereon.

Figure 6 is a view showing the electrical and optical properties of the pn junction GaN nanorods LED prepared according to the present invention.

FIG. 6A is an SEM photograph and graph Z of FIG. 6B is an I-V characteristic graph for the LED of FIG. 6A. The scale bar size of FIG. 6A is 10 μm, and the diameter of the nanorod is 50 nm. Look at graph Z. You can see that the LEDs have a good rectifying behavior and turn on at a forward voltage of 0.25V.

Graph X shows that the Ni / Au electrode is indeed p-type GaN nanorods, not pn junctions, to determine whether they are in ohmic contact with p-GaN 220b. The Ni / Au electrode was placed on the plate, and the IV characteristics between the p-type GaN nanorod and the Ni / Au electrode were measured.

Then, graph Y shows that the Ti / Al electrode is really in ohmic contact with the n-GaN 220a, and forms an n-type GaN nanorod, and then lays it on an LED substrate and puts the Ti / Al electrode on it. The IV characteristics between the n-type GaN nanorods and Ti / Al electrodes were measured. As the graphs X and Y show linear behavior, it can be seen that ohmic contact is performed properly.

FIG. 6C is a luminescence image when a 3V forward bias is applied to the LED of FIG. 6A, and the result of measuring the emission spectrum at this time is FIG. 6D. In FIG. 6D, the emission peak of the blue region is observed at 3.179 eV regardless of the current injection.

As described above, according to the present invention, by using the HVPE method to form a pn junction GaN nanorod at a low temperature of 400 ~ 600 ℃ LED device can be made with one GaN nanorod.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (6)

The n-type is grown by supplying GaClx gas and NH3 gas into a reactor loaded with a growth substrate and reacting these gases at a temperature range of 400 to 600 ° C. The p-type is formed of GaClx gas, NH3 gas, and acceptor-containing gas. Supplying the gas into the reactor and reacting and growing these gases at a temperature in the range of 400 to 600 ° C. to form a pn junction nanorod on the growth substrate for 30 minutes to 10 hours; Cutting the pn junction GaN nanorods formed on the growth substrate; And And forming a metal electrode in ohmic contact with the p-type and n-type regions, respectively, on the cut-out pn-bonded GaN nanorod. The method of claim 1, wherein the forming of the metal electrode comprises: Laying the cut pn-bonded GaN nanorods on a substrate for LEDs; And And depositing the metal electrode on the substrate for the LED so as to cover both end portions of the pn-bonded GaN nanorods, respectively. The method of claim 2, wherein the surface of the LED substrate on which the pn-bonded GaN nanorods are laid down is made of an insulator. The method of claim 1, wherein the acceptor-containing gas is a Cp 2 Mg gas or an MgCl gas. The method of claim 1, wherein the metal electrode in ohmic contact with the p-type is a Ni / Au electrode. The method of claim 1, wherein the metal electrode in ohmic contact with the n-type is a Ti / Al electrode.

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