Light emitting diode

• US 7,982,207 B2
• Filed: 11/09/2010
• Issued: 07/19/2011
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Seoul Optodevice Company Limited (Seoul Semiconductor Co., Ltd.)
• Inventors: Kim, Hwa Mok, Kim, Dae Won, Kal, Dae Sung
• Primary Examiner(s): DANG, TRUNG Q
• Application Number:
  US12/942,635
• Publication Number:
  US 20110049472A1
• Time in Patent Office: 252 Days
• Field of Search: 257/13, 257/79, 257/E33.068
• US Class Current: 257/13
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/465 with a resonant cavity structure

Abstract

A light emitting diode (LED) has an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and a transparent electrode layer. The LED includes a tunnel layer interposed between the p-type semiconductor layer and the transparent electrode layer, an opening arranged in the transparent electrode layer so that the tunnel layer is exposed, a distributed Bragg reflector (DBR) arranged in the opening, and an electrode pad arranged on the transparent electrode layer to cover the DBR in the opening.

Claims

1. A light emitting diode, comprising:

a substrate;

an n-type semiconductor layer, an active layer, and a p-type semiconductor layer arranged on the substrate;

a transparent electrode layer arranged on and in contact with the p-type semiconductor layer, the transparent electrode layer comprising an opening exposing the p-type semiconductor layer;

a current blocking portion arranged in the opening; and

an electrode pad arranged on the current blocking portion.

2. The light emitting diode of claim 1, wherein the current blocking portion comprises SiO₂, Al₂O₃, Si₃N₄, and/or TiO₂.

3. The light emitting diode of claim 1, wherein the current blocking portion comprises a distributed Bragg reflector (DBR).

4. The light emitting diode of claim 3, wherein the DBR comprises a higher light reflectivity than the electrode pad.

5. The light emitting diode of claim 3, wherein the DBR comprises a plurality of low-refractivity layers and high-refractivity layers alternately stacked, the low refractivity layers comprising SiO₂ or Al₂O₃ and the high refractivity layers comprising Si₃N₄ or TiO₂.

6. The light emitting diode of claim 1, wherein the electrode pad extends into the opening of the transparent electrode layer.

7. The light emitting diode of claim 6, wherein the electrode pad is arranged directly on an upper surface of the transparent electrode layer outside of the opening.

8. The light emitting diode of claim 5, wherein one of the low-refractivity layers directly contacts the p-type semiconductor layer.

9. The light emitting diode of claim 5, wherein one of the high-refractivity layers directly contacts the electrode pad.

10. The light emitting diode of claim 5, wherein a first thickness is represented by the formula t₁=mλ

/4n_l, wherein m comprises an odd number, λ

comprises a wavelength of light, and n_l comprises a refractive index of the low-refractivity layers,

wherein a second thickness is represented by the formula t₂=mλ

/4n_h, wherein m comprises the odd number, λ

comprises the wavelength of light, and n_h comprises a refractive index of the high-refractivity layers,

wherein the low-refractivity layers comprise the first thickness and the high-refractivity layers comprise the second thickness, and

wherein the DBR comprises a reflectance of at least 95% in light comprising the wavelength λ

.

11. The light emitting device of claim 10, wherein the wavelength λ

corresponds to the peak emission wavelength of the active layer.

12. The light emitting device of claim 3, wherein the DBR blocks current from directly flowing between the electrode pad and the p-type semiconductor layer.

13. The light emitting device of claim 1, further comprising a lower DBR interposed between the active layer and the substrate.

14. The light emitting device of claim 13, wherein the lower DBR comprises a plurality of low-refractivity layers and high-refractivity layers alternately stacked.

15. The light emitting device of claim 13, wherein light emitted by the active layer and/or reflected by the current blocking layer is reflected toward the transparent electrode layer by the lower DBR.

16. A light emitting diode, comprising:

a substrate;

an n-type semiconductor layer, an active layer, and a p-type semiconductor layer arranged on the substrate;

a transparent electrode layer arranged on the p-type semiconductor layer, the transparent electrode layer comprising an opening exposing the p-type semiconductor layer;

a current blocking portion arranged in the opening; and

an electrode pad arranged on the current blocking portion,

wherein the current blocking portion comprises a distributed Bragg reflector (DBR) comprising a plurality of low-refractivity layers and high-refractivity layers alternately stacked, the low refractivity layers comprising SiO₂ or Al₂O₃ and the high refractivity layers comprising Si₃N₄ or TiO₂,

wherein the low-refractivity layers comprise a first thickness, and the high-refractivity layers comprise a second thickness, the first thickness being represented by the formula t₁=mλ

/4n_l, wherein m comprises an odd number, λ

comprises a wavelength of light, and n_l comprises a refractive index of the low-refractivity layers, and the second thickness being represented by the formula t₂=mλ

/4n_h, wherein m comprises the odd number, λ

comprises the wavelength of light, and n_h comprises a refractive index of the high-refractivity layers, and

wherein the DBR comprises a reflectance of at least 95% in light comprising the wavelength λ

.

17. The light emitting device of claim 16, further comprising a tunnel layer interposed between the p-type semiconductor layer and the transparent electrode layer.