KR20100129048A - Efficient light emission diode structure for adopting with contact metal electrode finger - Google Patents

Abstract

PURPOSE: A highly efficient light emission diode structure is provided to improve the light efficiency even in the low forward voltage by forming the structure of a contact metal electrode of P type and N type in finger type. CONSTITUTION: A n-type contact metal electrode(22) is electrically connected to a n-type nitride semiconductor layer(20). The n-type contact metal electrode is made of Ni, Au, or their alloy. A transparent conductive film(52) is formed on the p-type nitride semiconductor layer. A p-type contact metal electrode(54) is formed on the partial area of the transparent conductive film.

Description

Efficient Light Emission Diode Structure for Adopting with Contact Metal Electrode Finger

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to light emitting diodes (LEDs). In particular, the p-type and n-type contact metal electrodes are structured with a finger type so that light efficiency is good even at low forward voltage and current can be dispersed. The present invention relates to a light emitting diode capable of maximizing light emission and achieving an even temperature distribution in the active layer.

The light emitting diode is a structure in which an active layer is bonded between a p-type semiconductor layer and an n-type semiconductor layer, and when a forward voltage is applied, the light emitting diode recombines the excited electrons in the active layer to emit light.

Such light emitting diodes are used as light emitting lamps of various electronic devices such as automobile dashboards, taillights, keyboards, traffic lights and LCD backlights.

However, typical light emitting diodes involve a lot of heat when emitting high brightness light in the active layer. Since heat generation in light emitting diodes reduces light efficiency and shortens lifetime, there is a demand for a light emitting diode structure capable of maximum light efficiency and optimal heat dissipation.

Accordingly, an object of the present invention is to solve the above-described problems, and an object of the present invention is to improve the efficiency of light even at low forward voltage and to provide a finger type structure of p-type and n-type contact metal electrodes to disperse current. It is possible to provide a light emitting diode capable of maximizing light emission and achieving an even temperature distribution in the active layer.

First, to summarize the features of the present invention, a light emitting diode according to an aspect of the present invention for achieving the above object of the present invention, the rectangular shape having an active layer between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer. A light emitting diode, comprising: forming an n-type contact metal electrode electrically connected to the n-type nitride semiconductor layer at some edges of the n-type nitride semiconductor layer, and the p-type except for the partial edge of the n-type nitride semiconductor layer After the transparent conductive film is formed on the nitride semiconductor layer, a p-type contact metal electrode is formed in a portion of the transparent conductive film, and the n-type contact metal electrode is formed at one end in the long direction of the n-type nitride semiconductor layer. 1 having a predetermined width and a predetermined length along left and right edges of the n-type nitride semiconductor layer in a symmetrical finger shape with respect to the bonding region The p-type contact metal electrode extending toward the center of the first bonding region in the form of a single finger at an inner neck of a second bonding region located at the other end in the longitudinal direction opposite to the first bonding region. It is characterized by extending to a predetermined width and a predetermined length.

The single finger of the p-type contact metal electrode may be within 3/4 of the long length.

The symmetrical fingers of the n-type contact metal electrode may be within a length from the neck to an end of the n-type nitride semiconductor layer opposite in the longitudinal direction.

The symmetrical fingers of the n-type contact metal electrode may be three quarters of the length from the neck to an end of the n-type nitride semiconductor layer opposite in the longitudinal direction.

The light emitting diode has a rectangular shape of 700 micrometers in a long direction and 350 micrometers or less in a unidirectional direction, and the symmetrical fingers of the n-type contact metal electrode have a width of 1 to 30 micrometers and a length of 5 to 600 micrometers. The single finger of the p-type contact metal electrode may be within 1 to 30 micrometers in width and within 5 to 500 micrometers in length.

The n-type nitride semiconductor layer is a Si-doped GaN layer, the p-type nitride semiconductor layer is a Mg-doped GaN layer, the active layer is a GaN barrier layer and In _x Ga _{1- x} N (0 <x <1) wells Layer.

The barrier layer or the well layer may be doped with at least one of Si, O, S, C, Ge, Zn, Cd, and Mg.

According to the light emitting diode according to the present invention, the structure of the p-type and n-type contact metal electrode as a finger (finger type), it is possible to obtain excellent light efficiency even at a low forward voltage, and to maximize the light emission structure in the active layer Even temperature distribution ensures stable operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Like reference numerals in the drawings denote like elements.

1 is a view for explaining a cross-sectional view of a light emitting diode according to an embodiment of the present invention.

Referring to FIG. 1, a light emitting diode according to an embodiment of the present invention includes an n-type nitride semiconductor layer 20, a GaN barrier layer (about 7.5 nanometers), and an In doped GaN layer (about 2 micrometers). _{0 .15} Ga _{0 .85} N well layer (2.5-nm or so) the number of times (five times), repeat the MQW (multi quantum well) structure in which an active layer (30), Al _{0 .12 0 .88} Ga N layer formed to a An electron blocking layer (EBL) 40 (about ²⁰ nanometers) and a p-type nitride semiconductor layer (about 100 nanometers) of a GaN layer (about 100 nanometers) doped with Mg (about 5 * 10 ¹⁹ Mg dopant concentration). It has a structure which laminated | stacked 50 in order. Both the InGaN well layer and the GaN barrier layer of the active layer 30 may be doped with a Si dopant concentration of about 1 * 10 ¹⁹ . The electron blocking layer 40 may also be doped with an Mg dopant concentration of about 5 * 10 ¹⁹ .

Here, the well layer constituting the active layer 30, but is heard for example a layer In _{0 .15} Ga _{0 .85} N, not limited to this, as shown in the _{In x Ga 1 -x N (0} <x <1), may be different from the ratio of in and Ga, in addition, the electron blocking layer 40 is Al _{0 .12} Ga _{0 .88} N layer but hear an example, not limited to this, Al _x Ga _{1 - x} N (0 As in <x <1), the ratio of Al and Ga may be different. In addition, the barrier layer or the well layer constituting the active layer 30 may be doped with at least one of Si, O, S, C, Ge, Zn, Cd, and Mg in addition to Si as described above.

As shown in FIG. 2, after etching to a depth of about 650 nanometers along some edges of the n-type nitride semiconductor layer 20, the n-type nitride semiconductor layer 20 and the n-type nitride semiconductor layer 20 are formed at some edges of the n-type nitride semiconductor layer 20. The n-type contact metal electrode 22 which is electrically connected is formed to a thickness of about 110 nanometers. The n-type contact metal electrode 22 may be made of Ni, Au, or an alloy thereof.

A transparent conductive film (ITO: In Tin Oxide) is formed on the p-type nitride semiconductor layer 50 except for some edges on which the n-type contact metal electrode 22 is formed, as in the n-type nitride semiconductor layer 20. In some regions on the transparent conductive film 52, the p-type contact metal electrode 54 is formed to a thickness of about 110 nanometers. The p-type contact metal electrode 54 may be made of Ni, Au, or an alloy thereof.

2 is a view for explaining a plan view of a light emitting diode according to an embodiment of the present invention.

The light emitting diode according to the embodiment of the present invention may have a square shape when viewed from the top, and as described above, the n-type nitride semiconductor layer 20 is formed at some edges of the n-type nitride semiconductor layer 20. ) And an n-type contact metal electrode 22 electrically connected thereto, and a transparent conductive film 52 is formed on the p-type nitride semiconductor layer 50 except for some edges of the n-type nitride semiconductor layer 20. After that, the p-type contact metal electrode 54 is formed in a partial region on the transparent conductive film 52. 2, the light emitting diode according to an embodiment of the present invention may be manufactured in a rectangular shape of 700 micrometers (L) in the long direction and 350 micrometers (W) in the unidirectional direction, in some cases as described above It can be manufactured to have less than or more long length and unidirectional length while maintaining the ratio of directional length and unidirectional length.

More specifically, the n-type contact metal electrode 22 has an n-type nitride semiconductor layer in the form of a symmetrical finger around the first bonding region located at one end in the long direction of the n-type nitride semiconductor layer 20 ( 20 may extend along a left and right edge of a predetermined width (eg, within a width of 1 to 30 micrometers) and a predetermined length (eg, within 5 to 600 micrometers). In addition, the p-type contact metal electrode 54 has a predetermined width toward the center of the first bonding region in the form of a single finger at the inner neck of the second bonding region located at the other end in the longitudinal direction opposite to the first bonding region. For example, within 1 to 30 micrometers) and to a predetermined length (eg, within 5 to 500 micrometers).

In particular, the length F1 of the single finger of the p-type contact metal electrode 54 is preferably about 1/2 of the longitudinal length L as shown in FIG. 2, but if it is generally within 3/4, a sufficiently good characteristic can be obtained. have.

Further, the symmetrical fingers as above on the n-type contact metal electrode 22 may be within a length F2 from the neck of the p-type contact metal electrode 54 to the end of the opposite n-type nitride semiconductor layer 20 in the longitudinal direction. Can be. FIG. 2 illustrates a case where the length of the symmetrical fingers as (3/4) * F2 of the n-type contact metal electrode 22 is set to (3/4) * F2, and FIG. 3 illustrates a case where the length is set to F2. 4 exemplifies a case where (1/2) * F2 is used.

In particular, as shown in FIG. 2, when the length of the symmetrical finger of the n-type contact metal electrode 22 is (3/4) * F2, excellent light emitting diode characteristics are shown as in FIGS. 5 to 9. It is preferable to select this.

In the light emitting diode according to the embodiment of the present invention, the bonding region of the n-type contact metal electrode 22 and the p-type contact metal electrode 54 is connected to the corresponding lead electrode of a predetermined lead frame, thereby forwarding. By applying a voltage of about 3.2V, light can be emitted by electrons excited in the active layer 30. The electron blocking layer 40 may prevent the electrons excited from the active layer 30 from escaping toward the p-type contact metal electrode 54 so that many electrons stay in the active layer 30 to increase the light efficiency. In addition, the active layer 30 may include an InGaN well layer (eg, six times) between GaN barrier layers (eg, six times), such as a GaN barrier layer-InGaN well layer-GaN barrier layer-InGaN well layer. For example, 5 times) is repeatedly formed so as to be sandwiched, thereby trapping excitation electrons in a well formed by an InGaN well layer having a band gap relatively lower than that of the GaN barrier layer, thereby further improving light efficiency. Can be increased.

FIG. 5 is a simulation result for describing the temperature distribution of the active layer 30 for the structure of FIG. 2.

As a result of simulation of the temperature distribution after operating the light emitting diode according to an embodiment of the present invention as shown in FIG. 2 at a forward voltage of about 3.2V, the high temperature region 510 is the end of a single finger of the p-type contact metal electrode 54. It can be seen that it is symmetrically distributed up, down, left and right about the part, and in this case, the difference between the maximum temperature of the center (301.37K) and the minimum temperature (300.31K) of the edge is only about 1.0K.

6 is a simulation result for explaining the current distribution of the active layer 30 for the structure of FIG.

As a result of simulation of current distribution for the light emitting diode according to an embodiment of the present invention as shown in FIG. 2 after operating at a forward voltage of about 3.2V, the high current density region 610 is formed by the single finger of the p-type contact metal electrode 54. Evenly distributed around the tip, in this case, the difference between the center maximum current density (22.68A / cm ² ) and the edge minimum current density (4.09A / cm ² ) is 20A / cm ² Within a few minutes was found.

FIG. 7 is a simulation result for describing the light emission power distribution of the active layer 30 for the structure of FIG. 2.

As a result of simulation of the light output power distribution after operating the light emitting diode according to the exemplary embodiment of the present invention as shown in FIG. 2 at a forward voltage of about 3.2V, the high power density region 710 is a single portion of the p-type contact metal electrode 54. Focusing on the tips of the finger can be seen to include a wide area uniformly minutes, in which case the difference between the center of the maximum power density (25.75W / cm ²⁾ and the minimum power density (5.12W / cm ²⁾ of the edge is 20W / It appeared about ² cm.

8 is a simulation result for explaining the current distribution of the n-type contact metal electrode 22 for the structure of FIG.

As a result of simulation of current distribution after operating the light emitting diode according to an embodiment of the present invention as shown in FIG. 2 at a forward voltage of about 3.2V, current is evenly distributed in the left and right fingers of the n-type contact metal electrode 22. It was confirmed that the current density at the fingertips of the left and right symmetry is superior to the structure of FIG. 3 or 4. In particular, it was confirmed that the current density at the fingertips 810 of the left and right symmetry of the n-type contact metal electrode 22 in the structure of Figure 2 is reduced by 45% compared to the structure of FIG.

9 is a simulation result for explaining the current distribution of the p-type contact metal electrode 54 for the structure of FIG.

As a result of simulation of current distribution for the light emitting diode according to an embodiment of the present invention as shown in FIG. 2 after operating at a forward voltage of about 3.2V, current is evenly distributed in a single finger under the neck of the p-type contact metal electrode 54. As a result, it was confirmed that the average current density region 910 is wider than the structure of FIG. 3 or FIG. 4.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a view for explaining a cross-sectional view of a light emitting diode according to an embodiment of the present invention.

2 is a view for explaining a plan view of a light emitting diode according to an embodiment of the present invention.

3 is a view for explaining another length of the n-type contact metal electrode in FIG.

4 is a view for explaining another length of the n-type contact metal electrode in FIG.

FIG. 5 is a simulation result for describing an active layer temperature distribution of the structure of FIG. 2.

FIG. 6 is a simulation result for describing an active layer current distribution of the structure of FIG. 2.

7 is a simulation result for describing an active layer light emission power distribution of the structure of FIG. 2.

FIG. 8 is a simulation result for describing a current distribution of an n-type contact metal electrode of the structure of FIG. 2.

FIG. 9 is a simulation result for describing a current distribution of a p-type contact metal electrode for the structure of FIG. 2.

Claims (7)

In the rectangular light emitting diode having an active layer between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer, Forming an n-type contact metal electrode electrically connected to the n-type nitride semiconductor layer at some edges of the n-type nitride semiconductor layer, Forming a transparent conductive film on the p-type nitride semiconductor layer except for the partial edges of the n-type nitride semiconductor layer, and then forming a p-type contact metal electrode in a partial region on the transparent conductive film, The n-type contact metal electrode has a predetermined width and a predetermined length along left and right edges of the n-type nitride semiconductor layer in a symmetrical finger shape with respect to the first bonding region located at one end in the long direction of the n-type nitride semiconductor layer. Prolonged, The p-type contact metal electrode extends a predetermined width and a predetermined length toward the center of the first bonding region in the form of a single finger in the inner neck of the second bonding region located at the other end in the longitudinal direction opposite to the first bonding region. Light emitting diodes, characterized in that. The method of claim 1, And the single finger of the p-type contact metal electrode is less than 3/4 of the long length. The method of claim 1, And the symmetrical fingers of the n-type contact metal electrode are within a length from the neck to an end of the n-type nitride semiconductor layer opposite in the longitudinal direction. 4. The light emitting diode of claim 3, wherein the left and right fingers of the n-type contact metal electrode are three quarters of a length from the neck to an end of the n-type nitride semiconductor layer opposite in the longitudinal direction. The method of claim 1, wherein the light emitting diode, Square shape of 700 micrometers in the longitudinal direction and 350 micrometers in the unidirectional direction, The symmetrical fingers of the n-type contact metal electrode are within 1 to 30 micrometers in width and within 5 to 600 micrometers in length, Wherein said single finger of said p-type contact metal electrode is within 1 to 30 micrometers in width and within 5 to 500 micrometers in length. The method of claim 1, The n-type nitride semiconductor layer is a Si-doped GaN layer, the p-type nitride semiconductor layer is an Mg-doped GaN layer, The active layer includes a GaN barrier layer and an In _x Ga _{1- x} N (0 <x <1) well layer. The method of claim 6, The barrier layer or the well layer is a light emitting diode, characterized in that doped with at least one of Si, O, S, C, Ge, Zn, Cd, Mg.

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