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Patent Issued for Semiconductor Light Emitting Device and Fabrication Method for Semiconductor Light Emitting Device

August 27, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- Fujitsu Limited (Kawasaki, JP) has been issued patent number 8802468, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Hatori, Nobuaki (Kanagawa, JP); Yamamoto, Tsuyoshi (Kawasaki, JP); Sudo, Hisao (Kawasaki, JP); Arakawa, Yasuhiko (Kanagawa, JP).

This patent was filed on June 5, 2013 and was published online on August 12, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "1) Field

"This embodiment relates to a semiconductor light emitting device having a ridge structure formed on a GaAs substrate such as a semiconductor light emitting device which operates, for example, as a light source for optical fiber communications and a fabrication method for the semiconductor light emitting device.

"2) Description of the Related Art

"In recent years, development of lasers for optical fiber communications whose operation wavelength is within a wavelength band longer than 1 .mu.m and in which a GaAs substrate is used such as quantum dot lasers, GaInNAs lasers and so forth is advancing.

"As one of such lasers for optical fiber communications as just described, a semiconductor laser having a ridge structure including an AlGaAs cladding layer has been proposed.

"In order to allow a semiconductor laser having a ridge structure including an AlGaAs cladding layer to operate in a single transverse mode, it is necessary to accurately control the width and the height of the ridge structure.

"Usually, the ridge structure is formed by etching, and the width thereof can be controlled with the width of an etching mask. Further, since the height of the ridge structure depends upon the depth of etching, the height can be controlled by such a method as control of etching time or insertion of an etching stop layer.

"Particularly, control of the etching depth is significant and, if the etching depth has a variation by approximately 0.1 .mu.m from a designed value, then the cutoff waveguide width of a higher-order transverse mode of the ridge waveguide varies by approximately .+-.0.5 .mu.m.

"Therefore, as a high accuracy etching method for a semiconductor laser having a GaAs/AlGaAs-related ridge structure, a method is known wherein an AlGaAs layer having a high Al composition ratio (for example, the Al composition ratio is approximately 0.5) is used as a cladding layer and a GaAs layer is used as an etching stop layer, and the etching depth is controlled with an AlGaAs/GaAs interface using fluoric acid capable of selectively etching an AlGaAs cladding layer as etchant (for example, refer to Japanese Patent Laid-Open No. Hei 5-304336)."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "One embodiment provides that a semiconductor light emitting device includes a lower cladding layer, an active layer, and an AlGaAs upper cladding layer mounted on a GaAs substrate, the semiconductor light emitting device having a ridge structure including the AlGaAs upper cladding layer, the semiconductor light emitting device further comprising an InGaAs etching stop layer provided in contact with the lower side of the AlGaAs upper cladding layer, the InGaAs etching stop layer having a band gap greater than that of the active layer.

"In addition, another embodiment provides that a fabrication method for a semiconductor light emitting device includes forming a lower cladding layer on a GaAs substrate, forming an active layer on the lower cladding layer, forming an InGaAs etching stop layer having a band gap greater than that of the active layer on the active layer, forming an AlGaAs upper cladding layer on the InGaAs etching stop layer, and exposing the InGaAs etching stop layer by selectively etching the AlGaAs upper cladding layer."

For the URL and additional information on this patent, see: Hatori, Nobuaki; Yamamoto, Tsuyoshi; Sudo, Hisao; Arakawa, Yasuhiko. Semiconductor Light Emitting Device and Fabrication Method for Semiconductor Light Emitting Device. U.S. Patent Number 8802468, filed June 5, 2013, and published online on August 12, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8802468.PN.&OS=PN/8802468RS=PN/8802468

Keywords for this news article include: Electronics, Semiconductor, Fujitsu Limited.

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Source: Electronics Newsweekly


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