Light emitting element and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-9349918-B2
Application number	US-201214232517-A
Country	US
Kind code	B2
Filing date	May 25, 2012
Priority date	Jul 12, 2011
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

A semiconductor light emitting element including, in a light extraction layer thereof, a photonic crystal periodic structure including two systems (structures) with different refractive indices. An interface between the two systems (structures) satisfies Bragg scattering conditions, and the photonic crystal periodic structure has a photonic band gap.

First claim

The invention claimed is:

1. A semiconductor light emitting element comprising, in a light extraction layer thereof, a photonic crystal periodic structure including first and second structures, each of which includes two substructures with different refractive indices formed along a X direction and a Y direction of a XY two-dimensional plane, wherein
one of the first and second structures comprises a different material from the material of the other of the first and second structures,
a design wavelength λ, a period a, and radius R that determine the photonic crystal periodic structure satisfy Bragg conditions at an interface between the two systems (structures),
a ratio (R/a) between the period a and the radius R is a value at which the photonic crystal periodic structure has the maximum photonic band gap, and
an order m of the Bragg conditions is an order m (where 1 <m <5) with which light extraction efficiency at the design wavelength λis determined to be maximum from a result of simulation analysis conducted with a FDTD method.

2. The semiconductor light emitting element according to claim 1 , wherein a depth h of the photonic crystal periodic structure is greater than or equal to 0.5 times a period a of the photonic crystal periodic structure.

3. The semiconductor light emitting element according to claim 1 , wherein the light extraction layer is one of a substrate of the semiconductor light emitting element or a protective film formed on a surface of the semiconductor light emitting element on a side opposite to the substrate.

4. The semiconductor light emitting element according to claim 3 , wherein the photonic crystal periodic structure is formed in a region of the substrate at a given depth position.

5. The semiconductor light emitting element according to claim 3 , wherein the photonic crystal periodic structure is formed to include holes that are periodically formed on a rear surface of the substrate.

6. The semiconductor light emitting element according to claim 1 , wherein the photonic crystal periodic structure includes two or more photonic crystal periodic structures that are formed in regions of one or more light extraction layers at a given depth position(s).

7. The semiconductor light emitting element according to claim 1 , wherein the photonic crystal periodic structure with the photonic band gap is a photonic crystal periodic structure whose period a and diameter d, which are parameters of the structure, are determined by a difference between a dielectric band (a first photonic band) of one of TE light or TM light and an air band (a second photonic band), the dielectric band (the first photonic band) having been determined through computation of eigen values of Maxwell's electromagnetic field wave equations Σε −1 (G−G′)|k+G∥k+G′|E(G′)=ω 2 /c 2 E(G′) and Σε −1 (G−G′)(k+G)*(k+G′)H(G′)=ω 2 /c 2 H(G)(where ε −1 denotes an inverse number of a dielectric constant, G denotes a reciprocal lattice vector, ω denotes frequency, c denotes light velocity, and k denotes a wave number vector), the equations have been obtained by expanding a plane wave output from the photonic crystal periodic structure by an electric field E and a magnetic field H.

8. The semiconductor light emitting element according to claim 7 , further comprising a photonic crystal periodic structure whose depth h is determined with a FDTD method.

9. The semiconductor light emitting element according to claim 1 , wherein the photonic crystal periodic structure of the light extraction layer is formed through processing using a nanoimprinting lithography method.

10. The semiconductor light emitting element according to claim 9 , wherein the photonic crystal periodic structure of the light extraction layer is formed through processing using a process of transferring a pattern of a die via a resin mold.

11. The semiconductor light emitting element according to- claim 1 , wherein the substrate includes sapphire.

12. The semiconductor light emitting element according to- claim 1 , wherein a semiconductor layer of the semiconductor light emitting element includes a nitride semiconductor.

13. The semiconductor light emitting element according to claim 9 , wherein the nanoimprinting lithography method includes the following steps 1) to 3):
1) in creating a master die for nanoimprinting, creating a resin mold to accommodate warping of the substrate, and transferring a pattern of the resin mold to a resist on the substrate, thereby preventing inversion between a pattern on the substrate and a pattern of the master die;
2) after the nanoimprinting, performing etching of the substrate through dry etching, wherein the die is created based on a period a, a diameter d, and a depth h, and the resin mold is obtained from the die, and then the pattern is transferred to the resist on the substrate through nanoimprinting, and further, the substrate is dry-etched and a residue of the resist is removed to measure the actual shape; and
3) creating a master die again by reflecting an etching bias value that is a difference between a measured value of the actual shape and a design value, performing the transfer and the dry etching, and removing a residue of the resist.

Assignees

• Kashima Yukio
• Matsuura Eriko
• Nishihara Hiromi
• Tashiro Takaharu
• Ookawa Takafumi
• Hirayama Hideki
• Fujikawa Sachie
• Youn Sung Won
• Takagi Hideki
• Kamimura Ryuichiro
• Osada Yamato
• Marubun Co Ltd
• Toshiba Machine Co Ltd
• Riken
• Ulvac Inc

Inventors

• Kashima Yukio
• Matsuura Eriko
• Nishihara Hiromi
• Tashiro Takaharu
• Ookawa Takafumi
• Hirayama Hideki
• Fujikawa Sachie
• Youn Sung Won
• Takagi Hideki
• Kamimura Ryuichiro
• Osada Yamato

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10H20/872

  Periodic patterns for optical field-shaping, e.g. photonic bandgap structures · CPC title

• H10H20/819 Primary

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

• H10H20/84

  Coatings, e.g. passivation layers or antireflective coatings · CPC title

• H10H20/825 Primary

  containing nitrogen, e.g. GaN · CPC title