Patents by Inventor Tsuyoshi Tojo
Tsuyoshi Tojo 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).
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Patent number: 6961359Abstract: Disclosed is a nitride based III-V group compound semiconductor laser device of ridge waveguide type with an oscillation wavelength of about 410 nm which has a low driving voltage, a high half-width value ?// of a FFP in a direction horizontal to a hetero interface, and a high kink level (i.e., good light output-injected current characteristics over the high-output range). This laser device is similar in structure to the related-art semiconductor laser device except for the current constricting layer formed in a ridge. It has a stacked film composed of an SiO2 film (600 ? thick) and an amorphous Si film (300 ? thick) which are formed on the SiO2 film by vapor deposition. The stacked film covers both sides of the ridge and a p-AlGaN cladding layer extending sideward from the base of the ridge.Type: GrantFiled: September 5, 2003Date of Patent: November 1, 2005Assignee: Sony CorporationInventors: Tsuyoshi Tojo, Shiro Uchida, Satoru Kijima
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Publication number: 20050227392Abstract: When a semiconductor light emitting device or a semiconductor device is manufactured by growing nitride III-V compound semiconductor layers, which will form a light emitting device structure or a device structure, on a nitride III-V compound semiconductor substrate composed of a first region in form of a crystal having a first average dislocation density and a plurality of second regions having a second average dislocation density higher than the first average dislocation density and periodically aligned in the first region, device regions are defined on the nitride III-V compound semiconductor substrate such that the device regions do not substantially include second regions, emission regions or active regions of devices finally obtained do not include second regions.Type: ApplicationFiled: June 9, 2005Publication date: October 13, 2005Inventors: Tsunenori Asatsuma, Shigetaka Tomiya, Koshi Tamamura, Tsuyoshi Tojo, Osamu Goto, Kensaku Motoki
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Patent number: 6954477Abstract: A method of fabricating a ridge-waveguide type semiconductor laser device having a large half-value width and a high kink level is provided. First, an effective refractive index difference ?n between an effective refractive index neff1 of the ridge and an effective refractive index neff2 of a portion on each of both sides of the ridge is taken as ?n=neff1?neff2, and a ridge width is taken as W. On such an assumption, constants “a”, “b”, “c”, and “d” of the following three equations are set on X-Y coordinates (X-axis: W, Y-axis: ?n) The first equation is expressed by ?n?a×W+b, where “a” and “b” are constants determining a kink level. The second equation is expressed by W?c, where “c” is a constant specifying a minimum ridge width at the time of formation of the ridge. The third equation is expressed by ?n?d, where “d” is a constant specified by a desired half-width value ?para.Type: GrantFiled: April 9, 2004Date of Patent: October 11, 2005Assignee: Sony CorporationInventors: Shiro Uchida, Tsuyoshi Tojo
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Publication number: 20050218422Abstract: A multi-beam semiconductor laser device capable of emitting respective laser beams with uniform optical output levels and enabling easy alignment is provided. This multi-beam semiconductor laser device (40) is a GaN base multi-beam semiconductor laser device provided with four laser stripes (42A, 42B, 42C and 42D) which are capable of emitting laser beams with the same wavelength. The respective laser oscillating regions (42A to 42D) are provided with a p-type common electrode (48) on a mesa structure (46) which is formed on a sapphire substrate (44), and have active regions (50A, 50B, 50C and 50D) respectively. Two n-type electrodes (52A and 52B) are provided on an n-type GaN contact layer (54) and located as common electrodes opposite to the p-type common electrode (48) on both sides of the mesa structure (46). The distance A between the laser stripe (42A) and the laser stripe (42D) is no larger than 100 ?m.Type: ApplicationFiled: May 19, 2005Publication date: October 6, 2005Inventors: Tsuyoshi Tojo, Tomonori Hino, Osamu Goto, Yoshifumi Yabuki, Shinichi Ansai, Shiro Uchida, Masao Ikeda
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Patent number: 6950451Abstract: A multi-beam semiconductor laser device capable of emitting respective laser beams with uniform optical output levels and enabling easy alignment is provided. This multi-beam semiconductor laser device (40) is a GaN base multi-beam semiconductor laser device provided with four laser stripes (42A, 42B, 42C and 42D) which are capable of emitting laser beams with the same wavelength. The respective laser oscillating regions (42A to 42D) are provided with a p-type common electrode (48) on a mesa structure (46) which is formed on a sapphire substrate (44), and have active regions (50A, 50B, 50C and 50D) respectively. Two n-type electrodes (52A and 52B) are provided on an n-type GaN contact layer (54) and located as common electrodes opposite to the p-type common electrode (48) on both sides of the mesa structure (46). The distance A between the laser stripe (42A) and the laser stripe (42D) is no larger than 100 ?m.Type: GrantFiled: June 14, 2002Date of Patent: September 27, 2005Assignee: Sony CorporationInventors: Tsuyoshi Tojo, Tomonori Hino, Osamu Goto, Yoshifumi Yabuki, Shinichi Ansai, Shiro Uchida, Masao Ikeda
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Publication number: 20050145856Abstract: The present invention provides a gallium nitride semiconductor device including an electrode composed of a metallic film on an underlying gallium nitride compound semiconductor layer. The gallium nitride semiconductor device is characterized in that recessed portions are present dispersely over the whole surface area of the underlying compound semiconductor layer in contact with the electrode metallic film in such a manner that at least two recessed portions having a depth greater than the lattice constant of crystals constituting the underlying compound semiconductor layer are present on a width direction line in any 1 ?m width region of the whole surface area.Type: ApplicationFiled: January 28, 2005Publication date: July 7, 2005Inventors: Tsunenori Asatsuma, Hiroshi Nakajima, Osamu Goto, Tsuyoshi Tojo
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Patent number: 6838703Abstract: The nitride-based semiconductor laser device 10 has a stacked structure comprising a first contacting layer 14, a first cladding layer 16, an active layer 20, a second cladding layer 24, a second contacting layer 26 and a second electrode 30 which are consecutively stacked, the second cladding layer 24 comprises a lower layer 24A and an upper layer 24B, the first cladding layer 14, the active layer 20 and the lower layer 24A of the second cladding layer have a mesa structure, the upper layer 24B of the second cladding layer and the second contacting layer 26 have a ridge structure, an insulating layer 40 covering at least part of each of both side surfaces of the upper layer 24B of the second cladding layer is formed on the portions of the lower layer 24A of the second cladding layer which portions correspond to the top surface of the mesa structure, and further, a metal layer 42 having substantially the same width as the mesa structure is formed on the top surface of the insulating layer 40 and the top surfaType: GrantFiled: February 13, 2004Date of Patent: January 4, 2005Assignee: Sony CorporationInventors: Takashi Yamaguchi, Takashi Kobayashi, Toshimasa Kobayashi, Satoru Kijima, Satoshi Tomioka, Shinichi Ansai, Tsuyoshi Tojo
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Publication number: 20040233955Abstract: A method of fabricating a ridge-waveguide type semiconductor laser device having a large half-value width and a high kink level is provided. First, an effective refractive index difference &Dgr;n between an effective refractive index neff1 of the ridge and an effective refractive index neff2 of a portion on each of both sides of the ridge is taken as &Dgr;n=neff1−neff2, and a ridge width is taken as W. On such an assumption, constants “a”, “b”, “c”, and “d” of the following three equations are set on X-Y coordinates (X-axis: W, Y-axis: &Dgr;n) The first equation is expressed by &Dgr;n≦a×W+b, where “a” and “b” are constants determining a kink level. The second equation is expressed by W≧c, where “c” is a constant specifying a minimum ridge width at the time of formation of the ridge.Type: ApplicationFiled: April 9, 2004Publication date: November 25, 2004Applicant: Sony CorporationInventors: Shiro Uchida, Tsuyoshi Tojo
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Publication number: 20040206975Abstract: In a multi-beam semiconductor laser including nitride III-V compound semiconductor layers stacked on one surface of a substrate of sapphire or other material to form laser structures, and including a plurality of anode electrodes and a plurality of cathode electrodes formed on the nitride III-V compound semiconductor layers, one of the anode electrodes is formed to bridge over one of the cathode electrodes via an insulating film, and another anode electrode is formed to bridge over another of the cathode electrodes via an insulating film.Type: ApplicationFiled: February 6, 2004Publication date: October 21, 2004Inventors: Tsuyoshi Tojo, Yoshifumi Yabuki, Shinichi Ansai, Tomonori Hino, Osamu Goto, Tsuyoshi Fujimoto, Osamu Matsumoto, Motonobu Takeya, Yoshio Oofuji
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Publication number: 20040170203Abstract: A multi-beam semiconductor laser device capable of emitting respective laser beams with uniform optical output levels and enabling easy alignment is provided. This multi-beam semiconductor laser device (40) is a GaN base multi-beam semiconductor laser device provided with four laser stripes (42A, 42B, 42C and 42D) which are capable of emitting laser beams with the same wavelength. The respective laser oscillating regions (42A to 42D) are provided with a p-type common electrode (48) on a mesa structure (46) which is formed on a sapphire substrate (44), and have active regions (50A, 50B, 50C and 50D) respectively. Two n-type electrodes (52A and 52B) are provided on an n-type GaN contact layer (54) and located as common electrodes opposite to the p-type common electrode (48) on both sides of the mesa structure (46). The distance A between the laser stripe (42A) and the laser stripe (42D) is no larger than 100 &mgr;m.Type: ApplicationFiled: December 12, 2003Publication date: September 2, 2004Inventors: Tsuyoshi Tojo, Tomonori Hino, Osamu Goto, Yoshifumi Yabuki, Shinichi Ansai, Shiro Uchida, Masao Ikeda
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Patent number: 6784010Abstract: The nitride-based semiconductor laser device 10 has a stacked structure comprising a first contacting layer 14, a first cladding layer 16, an active layer 20, a second cladding layer 24, a second contacting layer 26 and a second electrode 30 which are consecutively stacked, the second cladding layer 24 comprises a lower layer 24A and an upper layer 24B, the first cladding layer 14, the active layer 20 and the lower layer 24A of the second cladding layer have a mesa structure, the upper layer 24B of the second cladding layer and the second contacting layer 26 have a ridge structure, an insulating layer 40 covering at least part of each of both side surfaces of the upper layer 24B of the second cladding layer is formed on the portions of the lower layer 24A of the second cladding layer which portions correspond to the top surface of the mesa structure, and further, a metal layer 42 having substantially the same width as the mesa structure is formed on the top surface of the insulating layer 40 and the top surfaType: GrantFiled: November 6, 2002Date of Patent: August 31, 2004Assignee: Sony CorporationInventors: Takashi Yamaguchi, Takashi Kobayashi, Toshimasa Kobayashi, Satoru Kijima, Satoshi Tomioka, Shinichi Ansai, Tsuyoshi Tojo
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Publication number: 20040164308Abstract: When a semiconductor light emitting device or a semiconductor device is manufactured by growing nitride III-V compound semiconductor layers, which will form a light emitting device structure or a device structure, on a nitride III-V compound semiconductor substrate composed of a first region in form of a crystal having a first average dislocation density and a plurality of second regions having a second average dislocation density higher than the first average dislocation density and periodically aligned in the first region, device regions are defined on the nitride III-V compound semiconductor substrate such that the device regions do not substantially include second regions, emission regions or active regions of devices finally obtained do not include second regions.Type: ApplicationFiled: November 21, 2003Publication date: August 26, 2004Inventors: Tsunenori Asatsuma, Shigetaka Tomiya, Koshi Tamamura, Tsuyoshi Tojo, Osamu Goto, Kensaku Motoki
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Publication number: 20040159848Abstract: The nitride-based semiconductor laser device 10 has a stacked structure comprising a first contacting layer 14, a first cladding layer 16, an active layer 20, a second cladding layer 24, a second contacting layer 26 and a second electrode 30 which are consecutively stacked, the second cladding layer 24 comprises a lower layer 24A and an upper layer 24B, the first cladding layer 14, the active layer 20 and the lower layer 24A of the second cladding layer have a mesa structure, the upper layer 24B of the second cladding layer and the second contacting layer 26 have a ridge structure, an insulating layer 40 covering at least part of each of both side surfaces of the upper layer 24B of the second cladding layer is formed on the portions of the lower layer 24A of the second cladding layer which portions correspond to the top surface of the mesa structure, and further, a metal layer 42 having substantially the same width as the mesa structure is formed on the top surface of the insulating layer 40 and the top surfaType: ApplicationFiled: February 13, 2004Publication date: August 19, 2004Applicant: Sony CorporationInventors: Takashi Yamaguchi, Takashi Kobayashi, Toshimasa Kobayashi, Satoru Kijima, Satoshi Tomioka, Shinichi Ansai, Tsuyoshi Tojo
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Patent number: 6777792Abstract: A conductive mounting board provided in a package has a recessed portion and a projecting portion, and an insulating mounting board is disposed on the recessed portion. The insulating mounting board is disposed on the recessed portion. The insulating mounting board has an insulating board on the surface of which a wiring portion is disposed. A semiconductor laser, constituted by stacked semiconductor layers each being made from a compound semiconductor composed of a group III based nitride, is disposed on the insulating mounting board and the conductive mounting board. An n-side electrode of the semiconductor laser is in contact with the insulating mounting board and a p-side electrode thereof is in contact with the conductive mounting board. Heat generated in the semiconductor laser is radiated via the conductive mounting board, and short-circuit between the n-side electrode and the p-side electrode is prevented by the insulating mounting board.Type: GrantFiled: July 9, 2002Date of Patent: August 17, 2004Inventors: Hiroshi Yoshida, Tsuyoshi Tojo, Masafumi Ozawa
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Publication number: 20040105473Abstract: Disclosed is a semiconductor laser including semiconductor layers stacked on a substrate, and a pair of resonator end surfaces opposed to each other in the direction perpendicular to the stacking direction. In this semiconductor laser, a light emission side reflecting film is formed on one of the resonator end surfaces. A refractive index of the reflecting film against an emission wavelength of laser light is set to a value between an effective refractive-index and a refractive index of the substrate. Disclosed is another semiconductor laser including: a light emission function layer stack including a cladding layer and an active layer formed on one plane of a translucent substrate; two electrodes having different polarities, which are provided on the light emission function layer stack side; and a light leakage preventive film formed on the other plane of the translucent substrate.Type: ApplicationFiled: November 25, 2003Publication date: June 3, 2004Inventors: Tsuyoshi Tojo, Shiro Uchida
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Patent number: 6721342Abstract: Disclosed is an array type semiconductor laser device including a plurality of semiconductor laser chips each of which has an active layer for forming a light emitting point, wherein the semiconductor laser chips are arrayed on the same substrate in such a manner as to be spaced from each other at intervals. In this laser device, an array configuration of the semiconductor laser chips is specified such that a gap between arbitrary adjacent two laser chips located inwardly from both outermost laser chips positioned at both the edges of the semiconductor laser device is wider than a gap between each of said outermost laser chips and an LD chip adjacent thereto. This laser device is advantageous in reducing the effect of thermal interference mutually exerted on the laser chips, thereby ensuring a thermal uniformity over the entire laser chips.Type: GrantFiled: January 15, 2003Date of Patent: April 13, 2004Assignee: Sony CorporationInventors: Yoshifumi Yabuki, Tsuyoshi Tojo
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Publication number: 20040056259Abstract: A semiconductor light emitting device made of nitride III-V compound semiconductors is includes an active layer made of a first nitride III-V compound semiconductor containing In and Ga, such as InGaN; an intermediate layer made of a second nitride III-V compound semiconductor containing In and Ga and different from the first nitride III-V compound semiconductor, such as InGaN; and a cap layer made of a third nitride III-V compound semiconductor containing Al and Ga, such as p-type AlGaN, which are deposited in sequential contact.Type: ApplicationFiled: June 25, 2003Publication date: March 25, 2004Inventors: Osamu Goto, Takeharu Asano, Yasuhiko Suzuki, Motonobu Takeya, Katsuyoshi Shibuya, Takashi Mizuno, Tsuyoshi Tojo, Shiro Uchida, Masao Ikeda
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Publication number: 20040056267Abstract: The present invention provides a gallium nitride semiconductor device including an electrode composed of a metallic film on an underlying gallium nitride compound semiconductor layer. The gallium nitride semiconductor device is characterized in that recessed portions are present dispersely over the whole surface area of the underlying compound semiconductor layer in contact with the electrode metallic film in such a manner that at least two recessed portions having a depth greater than the lattice constant of crystals constituting the underlying compound semiconductor layer are present on a width direction line in any 1 &mgr;m width region of the whole surface area.Type: ApplicationFiled: May 27, 2003Publication date: March 25, 2004Inventors: Tsunenori Asatsuma, Hiroshi Nakajima, Osamu Goto, Tsuyoshi Tojo
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Patent number: 6711197Abstract: Disclosed is a nitride based III-V group compound semiconductor laser device of ridge waveguide type with an oscillation wavelength of about 410 nm which has a low driving voltage, a high half-width value &thgr;// of a FFP in a direction horizontal to a hetero interface, and a high kink level (i.e., good light output-injected current characteristics over the high-output range). This laser device is similar in structure to the related-art semiconductor laser device except for the current constricting layer formed in a ridge. It has a stacked film composed of an SiO2 film (600 Å thick) and an amorphous Si film (300 Å thick) which are formed on the SiO2 film by vapor deposition. The stacked film covers both sides of the ridge and a p-AlGaN cladding layer extending sideward from the base of the ridge.Type: GrantFiled: April 11, 2002Date of Patent: March 23, 2004Assignee: Sony CorporationInventors: Tsuyoshi Tojo, Shiro Uchida, Satoru Kijima
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Publication number: 20040047381Abstract: Disclosed is a nitride based III-V group compound semiconductor laser device of ridge waveguide type with an oscillation wavelength of about 410 nm which has a low driving voltage, a high half-width value &thgr;// of a FFP in a direction horizontal to a hetero interface, and a high kink level (i.e., good light output-injected current characteristics over the high-output range). This laser device is similar in structure to the related-art semiconductor laser device except for the current constricting layer formed in a ridge. It has a stacked film composed of an SiO2 film (600 Å thick) and an amorphous Si film (300 Å thick) which are formed on the SiO2 film by vapor deposition. The stacked film covers both sides of the ridge and a p-AlGaN cladding layer extending sideward from the base of the ridge.Type: ApplicationFiled: September 5, 2003Publication date: March 11, 2004Inventors: Tsuyoshi Tojo, Shiro Uchida, Satoru Kijima