LIGHT EMITTING DEVICE
This disclosure discloses a light-emitting device. The light-emitting device comprises a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer; a reflective structure formed on the first-type semiconductor layer; and a first interface and a second interface formed between light-emitting stack and the reflective structure; wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface, and an area of the first interface is more than an area of the second interface.
This application is a Continuation application of U.S. application Ser. No. 14/261,368, filed on Apr. 24, 2014, which claims priority to TW application Serial No. 102114988, filed on Apr. 25, 2013, the entire contents of each being hereby incorporated by reference.
BACKGROUND Technical FieldThe present disclosure relates to a light-emitting device, and in particular to a light-emitting device comprising a reflective structure.
Description of the Related ArtThe light-emitting diodes (LEDs) of the solid-state lighting elements have the characteristics of low power consumption, low heat generation, long operational life, shockproof, small volume, quick response and good opto-electrical property like light emission with a stable wavelength so the LEDs have been widely used in household appliances, indicator light of instruments, and opto-electrical products, etc. However, how to improve a lighting efficiency of the LEDs is still an important issue.
In addition, the LEDs can be further connected to other components (such as submount) in order to form a light emitting apparatus (ex. a light-emitting package structure). The light emitting apparatus comprise one submount with a circuit, a solder formed on the submount for mounting the LEDs on the submount such that a substrate of the LEDs is electrically connected to the circuit, and an electrical connection structure for electrically connecting bonding pads with the circuit. The submount can be a lead frame or a mounting substrate with a larger size for easily designing a circuit layout thereon and for increasing heat dissipation efficiency.
SUMMARY OF THE DISCLOSUREThe present disclosure provides a light-emitting device with a reflective structure.
This light-emitting device, comprising: a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer; a reflective structure formed on the first-type semiconductor layer; and a first interface and a second interface formed between light-emitting stack and the reflective structure; wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface, and an area of the first interface is more than an area of the second interface.
This light-emitting device, comprising: a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer; a reflective structure formed on the first-type semiconductor layer; and a first interface and a second interface formed between the light-emitting stack and the reflective structure; wherein the reflective structure comprises a transparent conductive layer and a void formed in the transparent conductive layer, and the first interface is formed between the transparent conductive layer and the first-type semiconductor layer; and wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface, and the reflective structure electrically connects to the first-type semiconductor layer at the first interface.
This light-emitting device, comprising: a light-emitting stack comprises a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer; a reflective structure formed on the first-type semiconductor layer; and a bonding structure covering the reflective structure and contacting the first-type semiconductor layer; wherein the reflective structure electrically connects to the first-type semiconductor layer.
The accompanying drawings are included to provide easy understanding of the application, and are incorporated herein and constitutes a part of this specification. The drawings illustrate the embodiments of the application and, together with the description, serves to illustrate the principles of the application.
To better and concisely explain the disclosure, the same name or the same reference number given or appeared in different paragraphs or figures along the specification should has the same or equivalent meanings while it is once defined anywhere of the disclosure.
The following shows the description of embodiments of the present disclosure in accordance with the drawings.
In this embodiment, the first-type semiconductor layer 161 is a p-type semiconductor layer and the second-type semiconductor layer 163 is an n-type semiconductor layer. Alternatively, the first-type semiconductor layer 161 is an n-type semiconductor layer and the second-type semiconductor layer 163 is a p-type semiconductor layer. The first-type semiconductor layer 161 and the second-type semiconductor layer 162 comprise one of AlGaAs, AlGaInP, AlInP, InGaP, GaP, and GaAs, or one of AlInGaN, InGaN, AlGaN and GaN. The dopant in the p-type semiconductor layer comprises Mg, Be, Zn, C or combinations thereof. The dopant in the n-type semiconductor layer comprises Si, P, As, Sb or combinations thereof. The active layer 162 comprises one of AlGaAs, AlGaInP, AlInP, InGaP, GaP, and GaAs, or one of AlInGaN, InGaN, AlGaN and GaN. The active layer can have a structure including single heterostructure (SH), double heterostructure (DH), or double-side double heterostructure (DDH), or multi-quantum well (MQW) structure. The substrate comprises GaAs, GaP, Ge, sapphire, glass, diamond, SiC, Si, GaN, ZnO, or other suitable material. The metal layer can be a single layer or a multi-layer and comprises Ag, Al, Au, Ni or combinations thereof. The first bonding layer, the second bonding layer, and the third bonding layer can be a single layer or a multi-layer, and comprise a metal material or a glue material. The metal material comprises Au, In, Sn, Ti, Pt, or combination thereof. The glue material comprises BCB, epoxy, or PDMS, silicone (SiOx), Al2O3, TiO2, SiNx or combinations thereof. The transparent conductive layer can comprise metal oxide, such as ITO, InO, SnO, CTO, ATO, AZO, ZTO, GZO, ZnO, IZO, IGO, GAZO, or diamond-like carbon or GaP. The void can contain air, N2, He, or Ar.
The foregoing description has been directed to the specific embodiments of this invention. It will be apparent to those having ordinary skill in the art that other alternatives and modifications can be made to the devices in accordance with the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
Claims
1. A light-emitting device, comprising:
- a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer;
- a reflective structure formed on the first-type semiconductor layer; and
- a first interface and a second interface formed between light-emitting stack and the reflective structure; wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface, and an area of the first interface is more than an area of the second interface.
2. The light-emitting device of claim 1, wherein the reflective structure comprises a transparent conductive layer, and the first interface is between the first-type semiconductor layer and the transparent conductive layer.
3. The light-emitting device of claim 1, wherein the reflective structure comprises a void, and the second interface is between the first-type semiconductor layer and the void.
4. The light-emitting device of claim 2, wherein the reflective structure comprises a metal layer contacting the transparent conductive layer.
5. The light-emitting device of claim 3, further comprising an electrode on the second-type semiconductor layer, wherein the void has a width larger than a width of the electrode from a cross section view of the light-emitting device.
6. The light-emitting device of claim 5, wherein the void is formed at a position corresponding to the electrode.
7. The light-emitting device of claim 1, further comprising a bonding structure covering the reflective structure and contacting the first-type semiconductor layer.
8. A light-emitting device, comprising:
- a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer;
- a reflective structure formed on the first-type semiconductor layer; and
- a first interface and a second interface formed between the light-emitting stack and the reflective structure; wherein the reflective structure comprises a transparent conductive layer and a void formed in the transparent conductive layer, and the first interface is formed between the transparent conductive layer and the first-type semiconductor layer; and
- wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface, and the reflective structure electrically connects to the first-type semiconductor layer at the first interface.
9. The light-emitting device of claim 8, wherein the reflective structure further comprises a metal layer contacting the transparent conductive layer.
10. The light-emitting device of claim 8, wherein the void contains air, N2, He, or Ar.
11. The light-emitting device of claim 8, wherein the void has a height smaller than 800 Å.
12. The light-emitting device of claim 8, further comprising an electrode on the second-type semiconductor layer, wherein the void is at a position corresponding to the electrode.
13. The light-emitting device of claim 12, wherein the void has a width larger than a width of the electrode structure from a cross section view of the light-emitting device.
14. The light-emitting device of claim 8, wherein the second interface is formed between the void and the first-type semiconductor layer.
15. A light-emitting device, comprising:
- a light-emitting stack comprises a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer;
- a reflective structure formed on the first-type semiconductor layer; and
- a bonding structure covering the reflective structure and contacting the first-type semiconductor layer;
- wherein the reflective structure electrically connects to the first-type semiconductor layer.
16. The light-emitting device of claim 15, wherein a first interface and a second interface formed between the light-emitting stack and the reflective structure, and a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface.
17. The light-emitting device of claim 16, wherein a third interface is formed between the bonding structure and the first-type semiconductor layer, and a critical angle at the third interface for the light emitted from the light-emitting stack is larger than that at the second interface.
18. The light-emitting device of claim 15, wherein the bonding structure is between a substrate and the light-emitting stack.
19. The light-emitting device of claim 15, wherein the bonding structure comprises a first bonding layer contacting the reflective layer and a second bonding layer devoid of contacting to the reflective layer.
20. The light-emitting device of claim 15, wherein the bonding structure comprises metal material.
Type: Application
Filed: Oct 25, 2017
Publication Date: Mar 1, 2018
Inventors: Yi-Ming CHEN (Hsinchu), Hao-Min KU (Hsinchu), Chih-Chiang LU (Hsinchu), Tzu-Chieh HSU (Hsinchu)
Application Number: 15/793,611