Semiconductor chip that emits polarized radiation

• US 9,312,441 B2
• Filed: 04/16/2012
• Issued: 04/12/2016
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Lindberg, Hans
• Primary Examiner(s): Crawford, Latanya N
• Application Number:
  US14/112,000
• Publication Number:
  US 20140131754A1
• Time in Patent Office: 1,457 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A semiconductor chip that emits radiation includes a semiconductor body having an active zone, which emits unpolarized radiation having a first radiation component of a first polarization and having a second radiation component of a second polarization. A lattice structure acts as a waveplate or polarization filter and causes an increase in one radiation component relative to the other radiation component in the radiation emitted by the semiconductor chip through an output side. Therefore, the semiconductor chip emits polarized radiation, which has the polarization of the amplified radiation component. The attenuated radiation component remains in the semiconductor chip an optical structure, which converts the polarization of at least part of the attenuated radiation component remaining in the semiconductor chip to the polarization of the amplified radiation component, and a reflective rear side opposite the output side.

Claims

1. A radiation-emitting semiconductor chip comprising:

a semiconductor body comprising an active zone configured to emit unpolarized radiation having a first radiation component of a first polarization and a second radiation component of a second polarization;

a grating structure configured to act as a waveplate or polarization filter and bring about an increase in one radiation component relative to the other radiation component in the radiation emitted by the semiconductor chip through a coupling-out side such that the semiconductor chip is configured to emit polarized radiation having the polarization of the amplified radiation component while the attenuated radiation component remains in the semiconductor chip;

an optical structure configured to convert the polarization of at least a part of the attenuated radiation component remaining in the semiconductor chip into the polarization of the amplified radiation component; and

a reflective rear side situated opposite the coupling-out side,

wherein the optical structure comprises a first group of structured regions and at least a second group of structured regions,

wherein each group of structured regions comprises at least one structured region having oblique side faces that run at an angle of greater than 0° and

less than 90°

obliquely with respect to a plane in which the grating structure extends,

wherein each group of structured regions comprises at least two of the structured regions, wherein the structured regions of one group of structured regions directly adjoin each other, and

wherein the first group of structured regions and the second group of structured regions are laterally spaced apart from each other.

2. The radiation-emitting semiconductor chip according to claim 1, wherein the grating structure comprises a plurality of alternately arranged first grating regions of a first material and second grating regions of a second material, and wherein the grating regions of the same material are at a distance from one another which is smaller than a wavelength of the radiation generated by the active zone.

3. The radiation-emitting semiconductor chip according to claim 2, wherein the first and second grating regions are embodied in strip-type fashion and are arranged parallel to one another.

4. The radiation-emitting semiconductor chip according to claim 2, wherein the first or second grating regions of the grating structure acting as a waveplate are formed from a material that is transmissive to the radiation generated in the active zone, wherein the material comprises SiO₂, GaAs, AlGaAs, InGaAlP or GaN.

5. The radiation-emitting semiconductor chip according to claim 1, wherein the first radiation component experiences a different phase shift than the second radiation component upon transmission through the grating structure acting as a waveplate.

6. The radiation-emitting semiconductor chip according to claim 5, wherein the grating structure acting as a waveplate is arranged between the active zone and the reflective rear side of the semiconductor chip, and wherein a distance between the active zone and the reflective rear side is set in such a way that, as a result of interference of radiation of the same polarization, one radiation component is amplified and the other radiation component is attenuated.

7. The radiation-emitting semiconductor chip according to claim 2, wherein the first grating regions of the grating structure acting as a polarization filter comprise a metal.

8. The radiation-emitting semiconductor chip according to claim 7, wherein one radiation component is transmitted at the grating structure acting as a polarization filter and the other radiation component is reflected.

9. The radiation-emitting semiconductor chip according to claim 7, wherein the grating structure acting as a polarization filter is arranged on a surface of the semiconductor body that is on the coupling-out side.

10. The radiation-emitting semiconductor chip according to claim 7, wherein the grating structure is a contact structure for current spreading.

11. The radiation-emitting semiconductor chip according to claim 2, wherein the optical structure comprises structured regions extending in a plane arranged parallel to a plane in which the grating structure extends, wherein the structured regions run transversely with respect to the grating regions and form with the latter an angle of greater than 0°

and less than 90°

.

12. The radiation-emitting semiconductor chip according to claim 11, wherein the structured regions run transversely with respect to the grating regions and form with the latter an angle of 45°

.

13. The radiation-emitting semiconductor chip according to claim 11, wherein the structured regions are arranged at least partly parallel to one another.

14. The radiation-emitting semiconductor chip according to claim 1, wherein the optical structure comprises structured regions having oblique side faces that run at an angle of 45°

obliquely with respect to a plane in which the grating structure extends.

15. The radiation-emitting semiconductor chip according to claim 1, wherein the structured regions are embodied as prisms or pyramids.

16. The radiation-emitting semiconductor chip according to claim 1, wherein the reflective rear side comprises the optical structure.

17. The radiation-emitting semiconductor chip according to claim 1, wherein a part of the semiconductor body is arranged between the first group and the second group of structured regions.