Light-emitting device and method for manufacturing the same

• US 7,179,672 B2
• Filed: 11/01/2004
• Issued: 02/20/2007
• Est. Priority Date: 12/28/2001
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sugiyama, Hitoshi, Tonotani, Junichi, Ohashi, Kenichi, Suzuki, Kenji, Asakawa, Koji, Fujimoto, Akira
• Primary Examiner(s): LOUIE, WAI SING
• Application Number:
  US10/976,987
• Publication Number:
  US 20050112886A1
• Time in Patent Office: 841 Days
• Field of Search: None
• US Class Current: 438/29
• CPC Class Codes: H01L 21/0271 comprising organic layers
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

A nanometer size roughened structure is formed on a surface of a light-emitting element, and luminous efficiency is improved.

The roughened structure on the surface of the light-emitting element of the invention is formed into the following shape such that the refractive index smoothly changes:

• • (1) the mean diameter of projections on the roughened surface is smaller than the light wavelength;
  • (2) a pitch of the roughened surface is irregular; and
  • (3) positions of the top and bottom of the roughened surface are distributed from their mean values within the light wavelength in order to give a smooth gradient of the refractive index.

The surface of such light-emitting element is obtained by forming a thin film on the surface of the light-emitting element using a resin composition which contains a block copolymer or graft copolymer and forms a micophase-separated structure in a self-organization manner; selectively removing at least one phase of the microphase-separated structure of the thin film formed on the surface; and etching the surface of the light-emitting element using the remaining phase as an etching mask.

Claims

1. A light-emitting device having a finely roughened structure on a surface of an inorganic light permeable layer formed on a surface of an outermost layer of a light-emitting side or on an outermost layer at a light-emitting side of a semiconductor layer constituting the light-emitting element, the surface having a surface property comprising following two conditions:

(1) a mean radius of gyration <

R>

of projections in the roughened surface structure is 1/20 or more and ½

or less of a light wavelength, and dispersion σ

_R of a radius of gyration is 1.05 or more and 2 or less, wherein <

R>

is represented by <

R>

=Σ

R²n_R/Σ

Rn_R where n_R denotes a number of projections having an arbitrary radius of gyration, and σ

_R is represented by σ

_R=<

R>

/(Σ

Rn_R/Σ

n_R) where n_R denotes a number of projections having an arbitrary radius of gyration; and

(2) a mean height <

H>

of projections in the roughened surface structure is 1/10 or more and 1 or less of the light wavelength, and dispersion σ

_H of the radius of gyration is 1.05 or more and 2 or less, wherein <

H>

is represented by <

H>

=Σ

H²n_H/Σ

Hn_H where n_H denotes the number of projections having an arbitrary height, σ

_H is represented by σ

_H=<

H>

/(Σ

Hn_H/Σ

n_H) where n_H denotes the number of projections having an arbitrary height.