|Publication number||USRE42422 E1|
|Application number||US 11/724,310|
|Publication date||Jun 7, 2011|
|Filing date||Mar 15, 2007|
|Priority date||Jun 27, 2001|
|Also published as||US6867426, US6972208, US8344353, US8932885, US20030003613, US20040197981, US20110220873, US20130115725, US20150123151|
|Publication number||11724310, 724310, US RE42422 E1, US RE42422E1, US-E1-RE42422, USRE42422 E1, USRE42422E1|
|Inventors||Min-Hsun Hsieh, Kuen-Ru Chuang, Shu-Wen Sung, Chia-Cheng Liu, Chao-Nien Huang, Shane-Shyan Wey, Chih-Chiang Lu, Ming-Jiunn Jou|
|Original Assignee||Epistar Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (4), Classifications (23), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to a light emitting diode, more specifically to a light emitting diode having a transparent substrate, and a method for manufacturing the same.
2. Description of the Related Art
Light emitting diodes (LEDs) are employed in a wide variety of applications including optical display devices, traffic lights, data storage equipment, communication devices, illumination apparatuses, and medical treatment equipment. Some of the main goals of engineers who design LEDs are to increase the brightness of the light emitted from LEDs and to reduce the cost of manufacturing LEDs.
U.S. Pat. No. 5,783,477 discloses a method of bonding two compound semiconductor surfaces to produce an ohmic contact interface. The method of manufacturing a prior art LED is to create an ohmic contact interface by aligning the crystallographic orientation and rotational alignment of two semiconductor surfaces and applying uniaxial pressure to the semiconductor wafers at a temperature of 1000° C. In actual procedure, however, it is difficult and expensive to align the crystallographic orientation and rotational alignment of the two semiconductor surfaces.
It is an objective of the claimed invention to provide a light emitting diode (LED) having a transparent substrate and the method for manufacturing the same. The method involves wafer bonding a transparent substrate with a compound semiconductor multilayer. The compound semiconductor multilayer comprising the LED is grown on a non-transparent substrate. The transparent substrate and the compound semiconductor multilayer are bonded using an amorphous interface layer. After the bonding, the non-transparent substrate is removed, leaving an LED with a transparent substrate. The method according to the claimed invention will simplify the procedure of manufacturing LEDs, thereby reducing costs. The method also solves the problem of aligning the crystallographic orientation and rotational alignment of the two semiconductor surfaces and creates a light emitting diode with an increased luminance.
In the claimed invention, a light emitting diode comprises a sapphire transparent substrate. Formed above the substrate is an indium tin oxide (ITO), a top surface of which comprises a first surface region and a second surface region. On the first surface region, the layers of the semiconductor multilayer stacked from bottom to top are: A p+-type contact layer of GaAs, a p-type cladding layer of AlGaInP, a multiple quantum well (MQW) light-emitting layer, an n-type cladding layer of AlGaInP, an n-type stop layer of AlGaAs, and an ITO transparent conductive layer. A first electrode is located on the ITO transparent conductive layer, and a second electrode is located on the second surface region.
The claimed invention also details a method for manufacturing the light emitting diode. The first step is to form a first multilayer on an n-type GaAs semiconductor substrate. An n-type stop layer of AlGaAs is formed on the semiconductor substrate. An n-type cladding layer of AlGaInP is formed on the n-type stop layer. An MQW light-emitting layer of AlGaInP is formed on the n-type cladding layer. A p-type cladding layer of AlGaInP is formed on the MQW light-emitting layer. A p+-type contact layer of GaAs is formed on the p-type cladding layer. A second multilayer is formed on a sapphire substrate. An amorphous interface layer of ITO IS formed on the sapphire substrate. A third multilayer is produced by placing the first multilayer on the second multilayer and bonding the first multilayer to the second multilayer by elevating temperature. Next, the n-type GaAs semiconductor substrate of the newly created third multilayer is removed, and an ITO transparent conductive layer is formed on the stop layer to produce a fourth multilayer. Next, an exposed interface region is formed by etching away a portion of the fourth multilayer from the ITO transparent conductive layer to the ITO amorphous interface layer. Finally, a first contact electrode and a second contact electrode are formed on the ITO transparent conductive layer and the exposed interface region, respectively.
These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
According to the description of these embodiments, LEDs having a transparent substrate can be manufactured by a method of bonding two chips using an amorphous interface layer. LEDs made according to the present invention are easier to manufacture, less expensive to manufacture, and brighter than those made according to the prior art.
While the invention has been disclosed and described with reference to these preferred embodiments, the scope of the invention is not limited to these preferred embodiments. Any variation and modifications of the invention still falls within the spirit and scope of the invention. For example, using a transparent conductive layer of adhesive agent instead of a single-crystal interface layer or using a single quantum well light-emitting layer instead of a multiple quantum well light-emitting layer cannot escape the scope and spirit of the invention. Moreover, the manufacturing method of the present invention is also suitable for manufacturing a light emitting diode having a non-transparent substrate.
Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
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|U.S. Classification||257/12, 257/37, 257/13|
|International Classification||H01L29/06, H01L31/0336, H01L31/072, H01L31/109, H01L31/0328, H01L33/30, H01L33/00, H01L21/20, H01L33/32, H01L21/8238, H01L21/00|
|Cooperative Classification||H01L33/02, H01L33/16, H01L33/42, H01L21/2007, H01L33/30, H01L33/0079, H01L33/32|
|European Classification||H01L21/20B2, H01L33/00G3D|