Light emitting element and image display device using the light emitting element

• US 8,779,454 B2
• Filed: 01/05/2011
• Issued: 07/15/2014
• Est. Priority Date: 01/07/2010
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Katayama, Ryuichi
• Primary Examiner(s): Tran, Thien F
• Application Number:
  US13/520,958
• Publication Number:
  US 20120280265A1
• Time in Patent Office: 1,287 Days
• Field of Search: 257/98, 257/79
• US Class Current: 257/98
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

The present invention provides a light emitting element which emits linearly polarized light, has high efficiency, can show a higher luminance and has also adequate productivity. The light emitting element that includes an active layer composed of a semiconductor which generates light includes: a polarizer layer that allows a polarized component in a first direction among the lights generated in the active layer to pass therethrough, reflects a polarized component in a second direction which is perpendicular to the first direction, is formed on a semiconductor of the same group as the active layer, and contains a semiconductor or a metal of the same group as the active layer; a reflective layer that is provided in the opposite side of the polarizer layer with respect to the active layer, and reflects light which has been reflected by the polarizer layer; and a wavelength plate layer that is provided between the polarizer layer and the reflective layer, changes polarization states of the light which has been reflected by the polarizer layer and the light which has been reflected by the reflective layer, and contains a semiconductor of the same group as the active layer.

Claims

1. A light emitting element comprising:

an active layer composed of a semiconductor which generates light;

a polarizer layer that allows a polarized component in a first direction among the lights generated in said active layer to pass therethrough, and reflects a polarized component in a second direction which is perpendicular to the first direction;

a reflective layer that is provided in the opposite side of said polarizer layer with respect to said active layer, and reflects light which has been reflected by said polarizer layer; and

a wavelength plate layer that is provided between said polarizer layer and said reflective layer, and changes polarization states of the light which has been reflected by said polarizer layer and light which has been reflected by said reflective layer, wherein

said polarizer layer is formed on a semiconductor of the same group as said active layer and contains a semiconductor or a metal of the same group as said active layer, and

said wavelength plate layer contains a semiconductor of the same group as said active layer.

2. The light emitting element according to claim 1, wherein

said polarizer layer has a structure in which a metal is formed into a stripe shape on the semiconductor of the same group as said active layer.

3. The light emitting element according to claim 1, wherein

said polarizer layer has a structure in which a first semiconductor formed into a stripe shape and a second semiconductor formed into a stripe shape are alternately stacked on the semiconductor of the same group as said active layer.

4. The light emitting element according to claim 1, wherein

the semiconductor composing said active layer is a semiconductor of groups III to V, said semiconductor of said groups III to V including In, Ga and N, and the semiconductor from which said polarizer layer is formed is a semiconductor of said groups III to V, said semiconductor of said groups III to V including Ga and N.

5. The light emitting element according to claim 1, wherein

the semiconductor composing said active layer is a semiconductor of groups III to V, said semiconductor of said groups III to V including In, Ga, Al and P, and a semiconductor from which said polarizer layer is formed is a semiconductor of said groups III to V, said semiconductor of said groups III to V including In, Ga, Al and P.

6. The light emitting element according to claim 1, wherein

said wavelength plate layer has a structure in which the semiconductor is formed into a stripe shape.

7. The light emitting element according to claim 1, wherein

the semiconductor composing said active layer is a semiconductor of groups III to V, said semiconductor of said groups III to V including In, Ga and N, and a semiconductor which included in said wavelength plate layer is a semiconductor of said groups III to V, said semiconductor of said groups III to V including Ga and N.

8. The light emitting element according to claim 1, wherein

the semiconductor composing said active layer is a semiconductor of groups III to V, said semiconductor of said groups III to V including In, Ga, Al and P, and a semiconductor which included in said wavelength plate layer is a semiconductor of said groups III to V, said semiconductor of said groups III to V including In, Ga, Al and P.

9. An image display device that uses the light emitting element according to claim 1.