Light-emitting device and method for manufacturing the same

• US 20050112886A1
• Filed: 11/01/2004
• Published: 05/26/2005
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Asakawa, Koji, Fujimoto, Akira, Sugiyama, Hitoshi, Suzuki, Kenji, Tonotani, Junichi, Ohashi, Kenichi
• Granted Patent: US 7,179,672 B2
• Time in Patent Office: Days
• US Class Current: 438/689
• 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

1-13. -13. (canceled)

14. 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 {fraction (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 {fraction (1/10)} or more and 1 or less of the light wavelength, and dispersion UH 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.