Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – In combination with or also constituting light responsive...
Reexamination Certificate
1999-08-11
2001-04-10
Chaudhuri, Olik (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
In combination with or also constituting light responsive...
C257S079000, C257S090000, C257S096000, C257S183000
Reexamination Certificate
active
06215131
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor light-emitting device, and particularly to a light-emitting device using a vacuum doughnut to serve as a current blocking layer.
2. Description of Prior Art
Generally speaking, light-emitting diodes that are characterized by a double heterojunction have low luminous efficiencies because of contact shadowing caused by current crowding at the p-n junction of the diode under the contact area. Referring to
FIG. 1
, a conventional light-emitting diode comprises a substrate
10
, a buffer layer
12
, a double heterostructure
14
, a cap layer
16
and metal contacts
18
a
and
18
b
. As external contact is made to the structure through the metal contact
18
b
, light is emitted along the double heterostructure
14
. However, the light emitted along the double heterostructure
14
under the contact
18
b
is absorbed or reflected by the contact, which in effect acts as a shadow to a portion of the light being emitted from the entire double heterostructure, thus reducing the total external light output. Therefore, in order to increase the output of the light being emitted along the entire double heterostructure of the diode, it is essential to minimize contact shadowing beneath the contact area.
SUMMARY OF THE INVENTION
Accordingly, the object of this invention is to provide a light-emitting device using a vacuum doughnut to serve as a current-blocking layer. The light emitted by the active region can be effectively outputted to the exterior, and thus the light efficiency of the light-emitting device is improved.
The vacuum doughnut can be formed in an epitaxial layer between the active layer and the upper electrode. It is not necessary to form a layer of semiconductor material or oxide to serve as a current-blocking layer in this invention, thus the structure and the manufacturing process of the light-emitting device can be simplified.
This invention forms a vacuum doughnut directly beneath the electrode so as to avoid useless current injection into the region directly beneath the electrode.
REFERENCES:
patent: 5300791 (1994-04-01), Chen et al.
patent: 5814838 (1998-09-01), Ohtsuka et al.
Chen Jian-Tin
Chen Tsong-Yu
Lai Wei-Chih
Advanced Epitaxy Technology Inc.
Chaudhuri Olik
Christensen O'Connor Johnson & Kindness PLLC
Louie Wai-Sing
LandOfFree
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