Ultraviolet light emitting device

Patent metadata

Field	Value
Publication number	US-9240533-B2
Application number	US-201514678104-A
Country	US
Kind code	B2
Filing date	Apr 3, 2015
Priority date	Sep 24, 2012
Publication date	Jan 19, 2016
Grant date	Jan 19, 2016

Abstract

Disclosed is a light emitting device including an active layer emitting light with a wavelength band of 200 nm to 405 nm, and a light-transmitting layer disposed on the active layer, the light-transmitting layer having a lower part facing the active layer, wherein at least one of side and upper parts of the light-transmitting layer has a surface-processed pattern portion.

First claim

What is claimed is:

1. A light emitting device, comprising:
an active layer emitting light; and
a light-transmitting layer disposed on the active layer, the light-transmitting layer having a lower part facing the active layer,
wherein at least one of side or upper parts of the light -transmitting layer has a surface-processed pattern portion, and
wherein the pattern portion is disposed in a non-maximum light emitting region, the non-maximum light emitting region being defined as follows:

F
<
y
<
h

,

where
⁢

⁢
0

≤
F
≤

(

a
+

b
1

2

)

⁢
tan
⁢

⁢

θ
TIR

0
<
x
<

(

b
1

-
a

)

2

where ‘y’ represents a position of the light-transmitting layer in a thickness direction, ‘x’ represents a position of the light-transmitting layer in a width direction, ‘a’ represents a width of the active layer, b 1 represents a width of the lower part of the light-transmitting layer, h represents a thickness of the light-transmitting layer, and θ TIR represents a total internal reflection angle of the light-transmitting layer.

2. The light emitting device according to claim 1 , wherein the active layer emits the light having a wavelength band of 200 nm to 405 nm.

3. The light emitting device according to claim 1 , wherein the pattern portion is disposed in at least one of the upper part of the light-transmitting layer, a lower portion, an intermediate portion, or an upper portion of the side part of the light-transmitting layer.

4. The light emitting device according to claim 3 , wherein the pattern portion is further disposed in at least one of lower portion as follows or intermediate portion of the side part of the light-transmitting layer

0
<
y
<

b
1

2

.

5. The light emitting device according to claim 3 , wherein the pattern portion is surface-processed to provide random roughness, or is surface-processed into a hemispherical shape.

6. The light emitting device according to claim 5 , wherein the surface-processing comprises at least one of lapping and polishing, a roughness level of the random roughness is proportional to a polishing particle size, and the surface -processing comprises laser scribing, wet etching, or dry etching.

7. The light emitting device according to claim 1 , wherein the pattern portion is surface-processed such that an upper surface and a lower surface of the light-transmitting layer have areas different from each other.

8. The light emitting device according to claim wherein the light-transmitting layer comprises:
a lower cut portion having a horizontal cross-section having the same shape as the lower surface; and
an upper cut portion being disposed on the lower cut portion and having a plurality of different horizontal cross-sections between an upper surface of the lower cut portion, and the upper surface of the light-transmitting layer.

9. The light emitting device according to claim wherein a side part of the upper cut portion has at least one inclined plane.

10. The light emitting device according to claim 9 , wherein the surface of the inclined plane has a roughness or the inclined plane has a concave or convex curvature at an outside.

11. The light emitting device according to claim 9 , wherein the following relation is present between a width of the upper surface and a width of the lower surface, of the light-transmitting layer
b 1 − b 2 =2 d tan θ 1

where b 1 represents the width of the lower surface, b 2 represents the width of the upper surface, ‘d’ represents a thickness of the upper cut portion and θ 1 represents an inclination angle of the inclined plane.

12. The light emitting device according to claim 9 , wherein the light-transmitting layer has a width of 50 μm to 250 μm, the lower cut portion has a thickness of 25 μm to 100 μm, and the inclined plane has an inclination angle of 30° to 40°.

13. The light emitting device according to claim 9 , wherein the upper cut portion has a head-truncated pyramidal shape, the upper cut portion has at least one projection at an edge thereof, or the upper cut portion has a reverse head-truncated pyramidal shape.

14. The light emitting device according to claim 1 , wherein the upper part of the light-transmitting layer has uniform irregularities as the pattern portion.

15. The light emitting device according to claim 14 , wherein a period of the irregularities is λ/4, wherein λ is a wavelength of the light.

16. The light emitting device according to claim 1 , further comprising:
a substrate;
a first conductive type semiconductor layer disposed between the substrate and the active layer; and
a second conductive type semiconductor layer disposed on the active layer,
wherein the light-transmitting layer comprises the second conductive type semiconductor layer.

17. The light emitting device according to claim 16 , further comprising a second conductive type electrode layer disposed on the second conductive type semiconductor layer,
wherein the light-transmitting layer further comprises the second conductive type electrode layer.

18. The light emitting device according to claim 1 , further comprising:
a first conductive type semiconductor layer disposed on the active layer;
a second conductive type semiconductor layer disposed under the active layer; and
a substrate disposed on the first conductive type semiconductor layer,
wherein the light-transmitting layer comprises the substrate.

19. A light emitting device, comprising:
a light emitting structure comprising a p-type semiconductor layer, an active layer emitting light and an n-type AlGaN layer; and
a sapphire substrate disposed on the n-type AlGaN layer and having a lower part facing the active layer,
wherein a pattern portion having roughness i

Assignees

• Lg Innotek Co Ltd

Inventors

• Lee Kwang Chil
• Park Joong Seo
• Lee Tae Lim
• Choi Woon Kyung
• Kim Kyoung Hoon
• Park Hae Jin
• Yun Hwan Hui

Classifications

• H10W72/552

  comprising metals or metalloids, e.g. silver · CPC title

• H10W72/20

  Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps · CPC title

• H10H20/825

  containing nitrogen, e.g. GaN · CPC title

• H10H20/819 Primary

  characterised by their shape, e.g. curved or truncated substrates · CPC title

• H10H20/82

  Roughened surfaces, e.g. at the interface between epitaxial layers · CPC title