Patent Application
20100127237
The present invention relates to an LED structure, particularly to a high-brightness LED structure and a method for fabricating the same.
LED (Light Emitting Diode) is a luminescent element, wherein current is applied to a III-V group compound semiconductor, and energy is released in form of light in the recombination of electrons and holes. LED does not burn as an incandescent lamp. Further, LED has a small volume, long service life, low driving voltage, high response speed and superior vibration resistance. Thus, LED can satisfy the demand for lightweight and compactness and has become a very popular product in daily living.
LED has greatly advanced in the performance and efficiency thereof and has been extensively used in daily living. Via different compound semiconductors and structures, LED may emit red, orange, yellow, green blue, violet, infrared, or ultraviolet light. Now, LED has been widely used in outdoor signboards, brake lights, traffic signs and display devices.
In principle, an LED is a sandwich structure having an N-type semiconductor layer, an active layer and a P-type semiconductor layer, which are formed via depositing four elements-aluminum, gallium, indium and phosphor, or alternatively formed of another semiconductor material, such as GaP (gallium phosphide), GaAlAs (gallium aluminum arsenide), GaAs (gallium arsenide). LED has a PN structure and a unidirectional conductivity. LED is generally deposited on a GaAs substrate. However, GaAs is a light-absorptive material and absorbs a portion of light emitted by the LED epitaxial layer. Thus, the light generated by LED is not fully utilized, and the brightness thereof is decreased.
The primary objective of the present invention is to provide a high-brightness LED structure and a method for fabricating the same.
The present invention proposes a high-brightness LED structure, which comprises a silicon substrate, a metal adhesion layer, a metal reflection layer, an N-type semiconductor layer, an active layer, and a P-type semiconductor layer, wherein the metal adhesion layer is stacked on the silicon substrate; the metal reflection layer is stacked on the metal adhesion layer; the N-type semiconductor layer is stacked on the metal reflection layer; the active layer is stacked on the N-type semiconductor layer; and the P-type semiconductor layer is stacked on the active layer.
The present invention also proposes a method for fabricating a high-brightness LED structure, which comprises steps: providing an N-type substrate; sequentially stacking on the N-type substrate a P-type semiconductor layer, an active layer, an N-type semiconductor layer and a metal reflection layer to form a first semi-product; preparing a silicon substrate; stacking a metal adhesion layer on the silicon substrate to form a second semi-product; bonding the metal reflection layer of the first semi-product to the metal adhesion layer of the second semi-product; and etching away the N-type substrate of the first semi-product to form the high-brightness LED structure of the present invention.
The present invention exempts the LED structure from using a light-absorptive GaAs substrate and uses the metal reflection layer to enhance light efficiency, whereby the generated light is fully utilized and the brightness is greatly increased.
Below, the technical contents of the present invention are described in detail with the embodiments. However, it should be understood that the embodiments are only to exemplify the present invention but not to limit the scope of the present invention. Refer to
The active layer 40 is stacked on the N-type semiconductor layer 30. The active layer 40 is a quantum well containing a period structure of GaInAlN (gallium indium aluminum nitride). The N-type semiconductor layer 30 includes an N-type cladding layer 31 and an N-type window layer 32. The N-type window layer 32 contacts the metal reflection layer 21, and the N-type cladding layer 31 contacts the active layer 40.
The P-type semiconductor layer 50 is stacked on the active layer 40. The P-type semiconductor layer 50 is made of a material selected from the group consisting of GaAs (gallium arsenide), GaP (gallium phosphide), GaInAlP (gallium indium aluminum phosphide), InAlP (indium aluminum phosphide), or GaAlAs (gallium aluminum arsenide). The P-type semiconductor layer 50 includes a P-type ohmic contact layer 51 and a P-type cladding layer 52, and the P-type cladding layer 52 contacts the active layer 40. A protection layer 60 is stacked on the P-type semiconductor layer 50. The protection layer 60 is made of silicon dioxide or silicon nitride. A contact pad 70 penetrates the protection layer 60 to contact the P-type semiconductor layer 50.
Refer to
In stacking the P-type semiconductor layer 50, a P-type ohmic contact layer 51 is stacked firstly, and then a P-type cladding layer 52 is stacked. In stacking the N-type semiconductor layer 30, an N-type cladding layer 31 is stacked firstly, and then an N-type window layer 32 is stacked. The method of the present invention also comprises steps: preparing a silicon substrate 10; and stacking a metal adhesion layer 20 on the silicon substrate 10 to form a second semi-product B (shown in
Refer to
Refer to
In conclusion, the present invention proposes a high-brightness LED structure and a method for fabricating the same, which needn't use a GaAs substrate, and which uses a metal reflection layer to reflect light. Therefore, the present invention can increase light efficiency and provide a high-brightness LED for users.
