Deep ultraviolet LED and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-10056526-B2
Application number	US-201615526860-A
Country	US
Kind code	B2
Filing date	Nov 1, 2016
Priority date	Mar 30, 2016
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

The light extraction efficiency of a deep ultraviolet LED is increased. The deep ultraviolet LED has a design wavelength λ, and includes, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, a metal layer, a p-GaN contact layer, a p-AlGaN layer that is transparent to light with the wavelength λ, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer. A thickness of the p-AlGaN layer is less than or equal to 100 nm. A reflecting photonic crystal periodic structure having a plurality of voids is provided in a region in a thickness direction including at least an interface between the p-GaN contact layer and the p-AlGaN layer such that the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN layer in a direction of the substrate. Maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the multi-quantum barrier layer (or the electron blocking layer) and less than or equal to 80 nm, and a depth h of each void is less than or equal to a total thickness of the p-AlGaN layer and the p-GaN contact layer. The reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components. A period a of the photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength λ. An order m in a formula of the Bragg condition satisfies 1≤m≤5. Provided that a radius of each void is R, R/a with which the photonic band gap becomes maximum is satisfied.

First claim

The invention claimed is:

1. A deep ultraviolet LED with a design wavelength λ, comprising, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, a metal layer, a p-GaN contact layer, a p-AlGaN layer that is transparent to light with the wavelength λ, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer,
wherein:
a thickness of the p-AlGaN layer is less than or equal to 100 nm,
a reflecting photonic crystal periodic structure having a plurality of voids is provided in a region in a thickness direction including at least an interface between the p-GaN contact layer and the p-AlGaN layer such that the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN layer in a direction of the substrate,
maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the one of the multi-quantum barrier layer or the electron blocking layer and less than or equal to 80 nm, and a depth h of each void is less than or equal to a total thickness of the p-AlGaN layer and the p-GaN contact layer,
the reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components,
a period a of the photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength λ,
an order m in a formula of the Bragg condition satisfies 1≤m≤5, and
provided that a radius of each void is R, R/a with which the photonic band gap becomes maximum is satisfied.

2. A deep ultraviolet LED with a design wavelength λ, comprising, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, an ultrathin metal layer, a p-AlGaN contact layer that is transparent to light with the wavelength λ, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer,
wherein:
a thickness of the p-AlGaN contact layer is less than or equal to 100 nm,
a reflecting photonic crystal periodic structure having a plurality of voids is provided within the p-AlGaN contact layer in a region in a thickness direction where the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN contact layer in a direction of the substrate,
maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the one of the multi-quantum barrier layer or the electron blocking layer and less than or equal to 80 nm, and when a depth h of each void is less than or equal to the thickness of the p-AlGaN contact layer,
the reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components,
a period a of the photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength λ,
an order m in a formula of the Bragg condition satisfies 1≤m≤5, and
provided that a radius of each void is R, R/a with which the photonic band gap becomes maximum is satisfied.

3. A deep ultraviolet LED with a design wavelength λ, comprising, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, a metal layer, a p-GaN contact layer, a p-AlGaN layer that is transparent to light with the wavelength λ, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer,
wherein:
a thickness of the p-AlGaN layer is less than or equal to 100 nm,
a reflecting photonic crystal periodic structure having a plurality of voids is provided in a region including at least an interface between the p-GaN contact layer and the p-AlGaN layer such that the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN layer in a direction of the substrate, penetrates the p-GaN contact layer and the metal layer from a thickness direction, and reaches an inside of the reflecting electrode layer but does not extend beyond the reflecting electrode layer,
maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the one of the multi-quantum barrier layer or the electron blocking layer and less than or equal to 80 nm,
the reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components,
a period a of the photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength λ,
an order m in a formula of the Bragg condition satisfies 1≤m≤5, and
provided that a radius of each void is R, R/a with which the photonic band gap becomes maximum is satisfied.

4. A deep ultraviolet LED with a design wavelength λ, comprising, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, an ultrathin metal layer, a p-AlGaN contact layer that is transparent to light with the wavelength λ, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer,
wherein:
a thickness of the p-AlGaN contact layer is less than or equal to 100 nm,
a reflecting photonic crystal periodic structure having a plurality of voids is provided at a position where the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN contact layer in a direction of the substrate, penetrates the ultrathin metal layer from a thickness direction, and reaches an inside of the reflecting electrode layer but does not extend beyond the reflecting electrode layer,
maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the one of the multi-quantum barrier layer or the electron blocking layer and less than or equal to 80 nm,
the reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components,
a period a of the photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength λ,
an order m in a formula of the Bragg condition satisfies 1≤m≤5, and
provided that a radius of each void is R, R/a with which the photonic band gap becomes maximum is satisfied.

5. A deep ultraviolet LED with a design wavelength λ, comprising, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, a metal layer, a p-GaN contact layer, a p-AlGaN layer that is transparent to light with the wavelength λ, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer,
wherein:
a thickness of the p-AlGaN layer is less than or equal to 100 nm,
a reflecting photonic crystal periodic structure having a plurality of voids is provided in a region including at least an interface between the p-GaN contact layer and the p-AlGaN layer such that the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN layer in a direction of the substrate and reaches an interface between the p-GaN contact layer and the metal layer from a thickness direction,
maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the one of the multi-quantum barrier layer or the electron blocking layer and les

Assignees

• Marubun Co Ltd
• Toshiba Machine Co Ltd
• Riken
• Ulvac Inc
• Tokyo Ohka Kogyo Co Ltd

Inventors

• Kashima Yukio
• Matsuura Eriko
• Kokubo Mitsunori
• Tashiro Takaharu
• Hirayama Hideki
• Kamimura Ryuichiro
• Osada Yamato
• Morita Toshiro

Classifications

• H01L33/0075

  Electricity · mapped topic

• H01L33/405

  Electricity · mapped topic

• H01L33/32 Primary

  Electricity · mapped topic

• H01L33/10

  Electricity · mapped topic

• H10H20/835

  Reflective materials · CPC title