The present invention relates to a semiconductor light emitting diode, and more particularly, to a light emitting diode with multi-layer reflector structure for improving its luminous efficiency and a method for fabricating the same.
Light emitting diodes (LEDs) as a luminous object have a variety of applications such as an optical communication or a display device, and are mainly manufactured based on GaAs, InP, GaN or the combination thereof.
LEDs are classified as surface emission type LEDs and edge emission type LEDs, depending on the methods of emitting light produced from an emission region to the outside. The surface emission type LED has a structure to emit light in a direction perpendicular to a junction surface. The surface emission type LED is particularly advantageous to provide high efficiency because light produced from an active layer is emitted outside without a self absorption loss.
In such a conventional surface emission type LED, however, the light refractive index of a material of the LED is greater than that of air of the outside to which light is emitted, regardless of the material of the LED. Therefore, due to a total reflection, only the light incident at an angle less than a specific angle with respect to the surface is emitted to the outside.
Generally, an LED chip has a section of a rectangular parallelepiped shape. In this case, the incident angle of light which is not emitted outside is not changed even through infinite reflections, thus decreasing the efficiency thereof.
Accordingly, an object of the present invention is to provide a high efficiency LED with multi-layer reflector structure for improving a luminous efficiency and a method for fabricating the same.
According to an aspect of the present invention, there is provided a high efficiency light emitting diode including: a compound semiconductor substrate with convex-concave portions symmetrical with respect to a first surface; an active layer disposed between the convex-concave portions over the compound semiconductor substrate; a p-type semiconductor layer disposed between the convex-concave portions on the active layer; an anode disposed between the convex-concave portions on the p-type semiconductor layer; an insulation layer formed along a profile of the first surface including the convex-concave portions on the semiconductor substrate, excluding an upper surface of the anode; a reflective layer disposed on the anode and an inclined surface of the insulation layer adjacent to the anode; and a cathode disposed on an edge of a second surface opposing to the first surface of the semiconductor substrate.
One or more reflective layers may be provided.
The reflective layer may be formed on a portion of the inclined surface of the insulation layer or may not be formed on the inclined surface of the insulation layer.
According to another aspect of the present invention, there is provided a method for fabricating a high efficiency light emitting diode, including: preparing a compound semiconductor substrate; sequentially forming an active layer and a p-type semiconductor layer on a surface of the compound semiconductor substrate; forming an anode on a predetermined portion of the p-type semiconductor layer; forming a masking pattern including a first masking pattern and a second masking pattern, the first masking pattern having a stepped configuration covering the anode, the second masking pattern being spaced apart from the first masking pattern to partially cover the p-type semiconductor layer; dry etching the masking pattern, the active layer, the p-type semiconductor layer and the semiconductor substrate, such that the masking pattern has a predetermined thickness; and wet etching the resulting structure to provide a smooth multi-layer convex-concave reflector having a stepped configuration around the anode.
The masking pattern may be formed of a silicon nitride layer, a silicon oxide layer, or a combination thereof.
The dry etching process may be performed in a plasma etching apparatus using a chlorine (Cl2) gas, a hydrobromide (HBr) gas, or a combination thereof, the plasma etching apparatus including a Reactive Ion Etching (RIE) apparatus, a Reactive Ion Beam Etching (RIBE) apparatus, and an Inductive Coupled Plasma (ICP) apparatus.
The wet etching process may be performed using one selected from the group consisting of a mixture solution of HBr+H3PO4+K2Cr2O7, a mixture solution of HBr+H2O2+H2O, and a mixture solution of Br2+methanol.
In the high efficiency LED and the method for fabrication the same according to the present invention, the structure of the LED is more efficient than the conventional LED and therefore it can be used as a light source having low power consumption and high brightness. Also, the LED can be fabricated using the existing semiconductor process, thus reducing the complexity of the fabricating process.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:
The present invention will now be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the present invention, and the scope of the present invention should not be construed as being limited to the embodiments set forth herein. Those skilled in the art can understand the present invention more fully through the embodiments set forth herein. In the drawings, the shapes of elements are exaggerated for clarity. The same reference numerals will be used throughout the drawings to refer to the same or like parts.
Referring to
The LED shown in
Even though three reflective layers 19 are provided in the above embodiment, the number of the reflective layers 19 may increase or decrease depending on characteristics and production cost of the desired device.
A method for fabricating the LED of
Referring to
The masking material 26 may be a silicon nitride (SiNx) layer, a silicon oxide (SiO2) layer or a combination thereof.
Referring to
A dry etching apparatus may include plasma etching apparatus such as a Reactive Ion Etching (RIE) apparatus, a Reactive Ion Beam Etching (RIBE) apparatus, an Inductive Coupled Plasma (ICP) apparatus, and the like, which is generally used for a semiconductor process. In the case where the dry etching process is performed using a chlorine gas or a hydrobromide gas, a GaAs or an InP is etched ten times faster than a silicon nitride layer or a silicon oxide layer. Thus, the stepped configuration formed on the semiconductor substrate is extended lengthwise in the structure shown in
Referring to
While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
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10-2006-0036057 | Apr 2006 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR06/02667 | 7/7/2006 | WO | 00 | 10/21/2008 |