Patents by Inventor Chiaki Sasaoka

Chiaki Sasaoka has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7760785
    Abstract: A method of forming a partially etched nitride-based compound semiconductor crystal layer includes the following steps. A non-crystal layer of a nitride-based compound semiconductor is formed. At least a part of the non-crystal layer is then etched to form a partially etched non-crystal layer before the partially etched non-crystal layer is crystallized to form a partially etched nitride-based compound semiconductor crystal layer.
    Type: Grant
    Filed: November 19, 2004
    Date of Patent: July 20, 2010
    Assignee: NEC Corporation
    Inventor: Chiaki Sasaoka
  • Patent number: 7741654
    Abstract: The present invention provides a semiconductor laser excellent in the current injection efficiency. In an inner stripe type semiconductor laser according to the present invention, a p type cladding layer 309 has a superlattice structure composed of GaN layers and Al0.1Ga0.9N layers, which are alternately layered on each other. The p type cladding layer 309 has a portion of high dislocation density and a portion of low dislocation density. That is, the dislocation density is relatively low in a region directly above an opening of the current-confining region 308, whereas the dislocation density is relatively high in a region directly above a current-confining region 308.
    Type: Grant
    Filed: September 15, 2005
    Date of Patent: June 22, 2010
    Assignee: NEC Corporation
    Inventors: Kazuhisa Fukuda, Chiaki Sasaoka, Akitaka Kimura
  • Publication number: 20100034231
    Abstract: A semiconductor laser, which emits a laser beam from an edge surface of an active layer (5), is provided with a protective film (20), arranged on the edge surface from which the laser beam is emitted, and formed of a single-layer or a multilayer dielectric film. Hydrogen concentration distribution in the protective film (20) is approximately flat. The active layer (5) is formed of a group-III nitride semiconductor including Ga as a constituent element. The protective film (20) is formed of at least a first protective film (21) that is in direct contact with an edge surface of the active layer (5), and a second protective film (22) that is in contact with the first protective film (21). A ratio of hydrogen concentration of the first protective film (21) with respect to hydrogen concentration of the second protective film (22) is not less than 0.5 and not more than 2.
    Type: Application
    Filed: August 4, 2009
    Publication date: February 11, 2010
    Applicant: NEC Electronics Corporation
    Inventors: Kazuhisa FUKUDA, Chiaki SASAOKA, Kentaro TADA, Toshiaki IGARASHI, Fumito MIYASAKA, Keiro KOMATSU
  • Publication number: 20080063020
    Abstract: The present invention provides a semiconductor laser excellent in the current injection efficiency. In an inner stripe type semiconductor laser according to the present invention, a p type cladding layer 309 has a superlattice structure composed of GaN layers and Al0.1Ga0.9N layers, which are alternately layered on each other. The p type cladding layer 309 has a portion of high dislocation density and a portion of low dislocation density. That is, the dislocation density is relatively low in a region directly above an opening of the current-confining region 308, whereas the dislocation density is relatively high in a region directly above a current-confining region 308.
    Type: Application
    Filed: September 15, 2005
    Publication date: March 13, 2008
    Applicant: NEC CORPORATION
    Inventors: Kazuhisa Fukuda, Chiaki Sasaoka, Akitaka Kimura
  • Publication number: 20060209395
    Abstract: Damages in the semiconductor layers at the chip separating surfaces are suppressed in a semiconductor laser employing a GaN-based semiconductor substrate made of GaN and AlGaN. Laminated layers including a n-type clad layer (502) made of AlGaN and a multi-quantum well (MQW) layer (504) serving to be an active layer is formed on an independent GaN substrate (501). The side surfaces of the laminated layers along the direction of the resonator are inclined in such a direction that the resonator width is decreased from the independent GaN substrate (501) to the laminated layers.
    Type: Application
    Filed: February 26, 2004
    Publication date: September 21, 2006
    Inventor: Chiaki Sasaoka
  • Publication number: 20060051939
    Abstract: Polycrystalline AlN 3 is deposited on the surface of an SiO2 film (2) by a sputtering method, and a mask is formed. An Si-doped n-GaN layer 5 is then formed over the mask thus formed. Subsequently, an n-type cladding layer (6), which is formed from Si-doped n-type Al0.1Ga0.9N (silicon concentration 4×1017 cm?3, thickness 1.2 ?m), an n-type light-trapping layer (7), which is formed from Si-doped n-type GaN, a multiple quantum well layer (8), which is formed from an In0.2Ga0.8N well layer and an Si-doped In0.05Ga0.95N barrier layer, a cap layer (9), which is formed from Mg-doped p-type Al0.2Ga0.8N, a p-type light-trapping layer (10), which is formed from Mg-doped p-type GaN, a p-type cladding layer (11), which is formed from Mg-doped p-type Al0.1Ga0.9N, and a p-type contact layer (12), which is formed from Mg-doped p-type GaN, are grown in sequence to form an LD layer structure.
    Type: Application
    Filed: August 30, 2004
    Publication date: March 9, 2006
    Applicant: NEC CORPORATION
    Inventors: Masaru Kuramoto, Chiaki Sasaoka, Masahige Matsudate
  • Publication number: 20050072986
    Abstract: A method of forming a partially etched nitride-based compound semiconductor crystal layer includes the following steps. A non-crystal layer of a nitride-based compound semiconductor is formed. At least a part of the non-crystal layer is then etched to form a partially etched non-crystal layer before the partially etched non-crystal layer is crystallized to form a partially etched nitride-based compound semiconductor crystal layer.
    Type: Application
    Filed: November 19, 2004
    Publication date: April 7, 2005
    Applicant: NEC CORPORATION
    Inventor: Chiaki Sasaoka
  • Patent number: 6841410
    Abstract: A method of forming a partially etched nitride-based compound semiconductor crystal layer includes the following steps. A non-crystal layer of a nitride-based compound semiconductor is formed. At least a part of the non-crystal layer is then etched to form a partially etched non-crystal layer before the partially etched non-crystal layer is crystallized to form a partially etched nitride-based compound semiconductor crystal layer.
    Type: Grant
    Filed: August 30, 2002
    Date of Patent: January 11, 2005
    Assignee: NEC Corporation
    Inventor: Chiaki Sasaoka
  • Publication number: 20030042496
    Abstract: A method of forming a partially etched nitride-based compound semiconductor crystal layer includes the following steps. A non-crystal layer of a nitride-based compound semiconductor is formed. At least a part of the non-crystal layer is then etched to form a partially etched non-crystal layer before the partially etched non-crystal layer is crystallized to form a partially etched nitride-based compound semiconductor crystal layer.
    Type: Application
    Filed: August 30, 2002
    Publication date: March 6, 2003
    Applicant: NEC CORPORATION
    Inventor: Chiaki Sasaoka
  • Patent number: 6284042
    Abstract: A MOVPE method is provided that makes it possible to grow a high-quality nitride crystal of a group III element. The method comprises the steps (a) to (d). In the step (a), an organometallic compound in a gas phase is supplied to a reaction chamber as a group III component material by a carrier gas. In the step (b), a nitrogen compound in a gas phase is supplied to the chamber as a group V component material by the carrier gas. In the step (c), a hydrocarbon in a gas phase is supplied to the chamber by the carrier gas. In the step (d), the organometallic compound and the nitrogen compound are reacted with each other in a atmosphere containing the hydrocarbon in the chamber to grow a nitride crystal of a group III element on a crystalline substrate. As the hydrocarbon, any hydrocarbon containing at least one carbon-to-carbon (i.e., C—C) bond in its molecule (i.e., alkanes) may be used. Preferably, any hydrocarbon containing at least one double or triple carbon-to-carbon bond (i.e.
    Type: Grant
    Filed: June 29, 2000
    Date of Patent: September 4, 2001
    Assignee: NEC Corporation
    Inventor: Chiaki Sasaoka
  • Patent number: 6100106
    Abstract: A process for producing a semiconductor light-emitting device, which comprises forming, on a substrate by crystal growth, a gallium nitride type compound semiconductor layer having a crystal face (0,0,0,1) which can be utilized as the end surface of an optical waveguide or as a cavity mirror surface.
    Type: Grant
    Filed: November 17, 1998
    Date of Patent: August 8, 2000
    Assignee: NEC Corporation
    Inventors: Atsushi Yamaguchi, Akitaka Kimura, Chiaki Sasaoka
  • Patent number: 6033490
    Abstract: In a method of manufacturing a semiconductor device which includes a quartz substrate having a z-cut plane of (0001) plane on a surface, a GaN film is first deposited on the surface. Finally, the quartz substrate is removed from the GaN film. The removed GaN film is used as a real substrate for forming GaN based compound semiconductor layers thereon.
    Type: Grant
    Filed: September 2, 1998
    Date of Patent: March 7, 2000
    Assignee: NEC Corporation
    Inventors: Akitaka Kimura, Chiaki Sasaoka, Koichi Izumi
  • Patent number: 5963787
    Abstract: A magnesium-doped semiconductor layer expressed by general formula Al.sub.x Ga.sub.1-x N (where 0.ltoreq.x.ltoreq.1) is formed on a substrate. Thereafter, on the semiconductor layer, a plurality of semiconductor layers (including an activation layer) expressed by general formula In.sub.x Al.sub.y Ga.sub.1-x-y N (where 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 0.ltoreq.x+y.ltoreq.1) are formed. The crystalline characteristics of semiconductor layers including a light emitting layer of a gallium nitride semiconductor light emitting device having a magnesium-doped gallium nitride semiconductor layer are good. Thus, in the case that the light emitting device is a laser device, it can be expected that the oscillating threshold value of the laser device becomes low. In the case that the light emitting device is a light emitting diode, it can be expected that the light emitting efficiency of the light emitting diode becomes high.
    Type: Grant
    Filed: July 14, 1998
    Date of Patent: October 5, 1999
    Assignee: NEC Corporation
    Inventors: Akitaka Kimura, Chiaki Sasaoka