Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – Plural light emitting devices
Reexamination Certificate
2002-01-23
2003-02-11
Pham, Long (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
Plural light emitting devices
C257S081000, C257S084000, C257S088000, C257S093000, C257S094000, C257S099000, C257S690000, C257S698000, C257S700000
Reexamination Certificate
active
06518598
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a structure of III-nitride light emitting diode (LED) and a manufacturing method thereof. More particularly, the present invention relates to the structure of III-nitride LED having spiral-shaped pattern electrodes, and the manufacturing method for making the same.
BACKGROUND OF THE INVENTION
Nowadays, because LED has advantages of low manufacturing cost, low manufacturing difficulty level, easy and convenient installation and promising development future, LED is used widely in daily life, such as electronic bulletin boards, indicator lights and car taillights, etc. However, how to further enhance the irradiation efficiency of LED is still a target on which engineers are working.
FIG. 1
a illustrates a top view of a structure of conventional III-nitride LED, and
FIG. 1
b
illustrates a cross-sectional view of a structure of conventional III-nitride LED along the A-A′ line in the
FIG. 1
a
. Referring to
FIG. 1
a
and
FIG. 1
b
first, an epitaxial structure is formed by forming a buffer layer
14
, a semiconductor layer
16
having a first electrical property, a confining layer
18
having the first electrical property, an active layer
20
, a confining layer
22
having a second electrical property, and a contact layer
24
having the second electrical property in sequence on a substrate
12
. Next, the aforementioned epitaxial structure is etched or polished to expose a portion of the semiconductor layer
16
having the first electrical property. Then, a transparent electrode
26
having the second electrical property, a metal electrode pad
30
having the second electrical property, and a metal electrode pad
28
having the first electrical property are formed on the epitaxial structure respectively, such as shown in
FIG. 1
a.
The transparent electrode
26
having the second electrical property is used in the structure of the convention LED
10
to increase the current-spreading efficiency. In fact, most of the current
32
is concentrated within the shortest distance between the transparent electrode
26
having the second electrical property and the metal electrode pad
28
having the first electrical property, such as shown in
FIG. 1
b
. Hence, the light-emitting area of LED
10
is mostly concentrated on the area on which the transparent electrode
26
having the second electrical property is close to the metal electrode pad
28
having the first electrical property, causing a poor light-emitting efficiency. Besides, due to the over-concentrated current, the temperature in local area is too high so that the life of conventional LED
10
is shortened. Although the prior art can increase the thickness of the transparent electrode
26
having the second electrical property to improve the current-spreading efficiency, yet as a result of that, the light permeability of the transparent electrode
26
having the second electrical property is reduced.
Further, in the conventional LED
10
, if the photon produced from the light-emitting layer is ejected to the surface of diode with a large angle, it easily leads to the loss of total reflection, thereby reducing the extraction efficiency.
SUMMARY OF THE INVENTION
In view of the disadvantages of the conventional LED structure, the present invention provides a structure of III-nitride LED and a manufacturing method thereof to overcome the disadvantages of the conventional LED structure directly and effectively.
According to the present invention, the structure of III-nitride LED having spiral electrodes comprises: a substrate; an epitaxial structure located on the substrate, the epitaxial structure comprising a first stacked sub-structure located on the substrate, and a second stacked sub-structure formed in a spiral-shaped pattern on the first stacked structure, wherein the second stacked sub-structure has a trench exposing a side of the second stacked sub-structure and a portion of the surface of first stacked sub-structure; a first metal electrode having a first electrical property, wherein the first metal electrode having the first electrical property is in the trench and is located on the portion of the surface of first stacked sub-structure in the spiral-shaped pattern along the second stacked sub-structure, and the first metal electrode having the first electrical property is connected with a first metal electrode having the first electrical property pad having the first electrical property; and an ohmic electrode having a second electrical property, wherein the ohmic electrode is located on the second stacked sub-structure, and the second electrical property is opposite to the first electrical property, the ohmic electrode having the second electrical property comprising a transparent electrode having the second electrical property on the second stacked sub-structure, and a second metal electrode having the second electrical property, wherein the second metal electrode having the second electrical property is located on the transparent electrode having the second electrical property and the second metal electrode having the second electrical property is connected with a second metal electrode pad having the second electrical property. Further, according to the present invention, the method of manufacturing the structure of III-nitride LED having spiral electrodes is described as follows.
According to the present invention, the III-nitride LED having spiral electrodes can increase the current-spreading efficiency due to the spiral-shaped pattern of electrodes. Besides, if the photon is ejected to the diode surface with a large angle, the photon can be extracted from the side of the trench that is exposed by etching or polishing the spiral-shaped pattern, whereby the extraction efficiency of photon is increased.
REFERENCES:
patent: 5952680 (1999-09-01), Strite
patent: 6255129 (2001-07-01), Lin
Epitech Corporation LTD
Louie Wai-Sing
Pham Long
LandOfFree
III-nitride LED having a spiral electrode does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with III-nitride LED having a spiral electrode, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and III-nitride LED having a spiral electrode will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3153853