Patents by Inventor Alistair Henderson Kean
Alistair Henderson Kean 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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Publication number: 20170218529Abstract: A cathode material comprising a titanium sheet and platinum, the platinum being in the form of nanoparticles deposited on at least one side of the titanium sheet, to form a decoration thereon, and processes for the preparation thereof.Type: ApplicationFiled: January 26, 2017Publication date: August 3, 2017Applicant: Johnson Matthey Public Limited CompanyInventors: Jonathan David Brereton SHARMAN, Alistair Henderson KEAN, Daniel OAKES, Edward Anthony WRIGHT
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Patent number: 6653248Abstract: A semiconductor layer is co-doped with two dopants. The first dopant is to generate charge carriers in the semiconductor material, and the second dopant is to promote atomic disorder within the material. When the semiconductor material is annealed, the second dopant becomes mobile and moves through the lattice so as to promote atomic disorder. This eliminates unwanted effects such as, for example, a reduction in the forbidden bandgap that can otherwise arise as a result of atomic ordering. The amount of diffusion of the second dopant during the annealing can be increased by making the initial concentration of the second dopant non-uniform over the volume of the semiconductor material.Type: GrantFiled: June 4, 2002Date of Patent: November 25, 2003Assignee: Sharp Kabushiki KaishaInventors: Alistair Henderson Kean, Haruhisa Takiguchi
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Patent number: 6500258Abstract: This invention relates to a method of growing a nitride semiconductor layer by molecular beam epitaxy comprising the steps of: a) heating a GaN substrate (S) disposed in a growth chamber (10) to a substrate temperature of at least 850° C.; and b) growing a nitride semiconductor layer on the GaN substrate by molecular beam epitaxy at a substrate temperature of at least 850° C., ammonia gas being supplied to the growth chamber (10) during the growth of the nitride semiconductor layer; wherein the method comprises the further step of commencing the supply ammonia gas to the growth chamber during step (a), before the substrate temperature has reached 800° C.Type: GrantFiled: June 18, 2001Date of Patent: December 31, 2002Assignee: Sharp Kabushiki KaishaInventors: Stewart Edward Hooper, Jonathan Heffernan, Jennifer Mary Barnes, Alistair Henderson Kean
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Publication number: 20020149030Abstract: A semiconductor layer is co-doped with two dopants. The first dopant is to generate charge carriers in the semiconductor material, and the second dopant is to promote atomic disorder within the material. When the semiconductor material is annealed, the second dopant becomes mobile and moves through the lattice so as to promote atomic disorder. This eliminates unwanted effects such as, for example, a reduction in the forbidden bandgap that can otherwise arise as a result of atomic ordering. The amount of diffusion of the second dopant during the annealing can be increased by making the initial concentration of the second dopant non-uniform over the volume of the semiconductor material.Type: ApplicationFiled: June 4, 2002Publication date: October 17, 2002Inventors: Alistair Henderson Kean, Haruhisa Takiguchi
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Patent number: 6440214Abstract: A method of growing a nitride semiconductor layer, such as a GaN layer, by molecular beam epitaxy comprises the step of growing a GaAlN nucleation layer on a substrate by molecular beam epitaxy. The nucleation layer is annealed, and a nitride semiconductor layer is then grown over the nucleation layer by molecular beam epitaxy. The nitride semiconductor layer is grown at a V/III molar ratio of 100 or greater, and this enables a high substrate temperature to be used so that a good quality semiconductor layer is obtained. Ammonia gas is supplied during the growth process, to provide the nitrogen required for the MBE growth process.Type: GrantFiled: June 9, 2000Date of Patent: August 27, 2002Assignee: Sharp Kabushiki KaishaInventors: Stewart Edward Hooper, Jennifer Mary Barnes, Jonathan Heffernan, Alistair Henderson Kean
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Patent number: 6426522Abstract: A semiconductor layer is co-doped with two dopants. The first dopant is to generate charge carriers in the semiconductor material, and the second dopant is to promote atomic disorder within the material. When the semiconductor material is annealed, the second dopant becomes mobile and moves through the lattice so as to promote atomic disorder. This eliminates unwanted effects such as, for example, a reduction in the forbidden bandgap that can otherwise arise as a result of atomic ordering. The amount of diffusion of the second dopant during the annealing can be increased by making the initial concentration of the second dopant non-uniform over the volume of the semiconductor material.Type: GrantFiled: June 14, 2000Date of Patent: July 30, 2002Assignee: Sharp Kabushiki KaishaInventors: Alistair Henderson Kean, Haruhisa Takiguchi
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Publication number: 20020093730Abstract: A semiconductor optical amplifier comprising an active gain region of the (In, Ga)(As, N) system is proposed, together with the use of (Ga, In)(As, N) as the base material for the fabrication of an SOA, and a semiconductor optical amplifier comprising (Ga, In)(As, N) as the base material. The N content of the (In, Ga)(As, N) can be varied along a dimension of the active region in the direction of propagation of light signals therein, to create a varying bandgap such as for mode expanders. The active region can be supplied by a source of electrical bias which is applied in segments along the dimension of the active region, the segments being capable of independent variation. This should allow channel equalisation of WDM signals to be performed dynamically. This scheme could also be used to equalise device parameters such as differential gain, saturation output power and linewidth enhancement factor across the amplification bandwidth.Type: ApplicationFiled: January 11, 2002Publication date: July 18, 2002Applicant: Kamelian LimitedInventors: Craig Tombling, Alistair Henderson Kean, Martin David Dawson, Anthony Edward Kelly
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Publication number: 20020093731Abstract: A semiconductor optical amplifier comprising an active gain region of the (In, Ga)(As, N) system is proposed, together with the use of (Ga,In)(As,N) as the base material for the fabrication of an SOA, and a semiconductor optical amplifier comprising (Ga,In)(As,N) as the base material. The N content of the (In,Ga)(As,N) can be varied along a dimension of the active region in the direction of propagation of light signals therein, to create a varying bandgap such as for mode expanders. The active region can be supplied by a source of electrical bias which is applied in segments along the dimension of the active region, the segments being capable of independent variation. This should allow channel equalisation of WDM signals to be performed dynamically. This scheme could also be used to equalise device parameters such as differential gain, saturation output power and linewidth enhancement factor across the amplification bandwidth.Type: ApplicationFiled: January 11, 2002Publication date: July 18, 2002Applicant: Kamelian LimitedInventors: Craig Tombling, Alistair Henderson Kean, Martin David Dawson, Anthony Edward Kelly
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Publication number: 20020080844Abstract: A lasing structure comprises a distributed feedback grating associated with the active region, the grating defined by a periodic structure of quantum well intermixing. This quantum well intermixing (QWI) can be caused by focussed ion beam (FIB) implantation to the quantum well (QW) or multi-quantum well (MQW) active area. Subsequent annealing of the FIB damage will leave local periodic adjustments to the energy levels in the active region, providing the necessary DFB/DBR grating. Alternatively, or in addition, this periodic QWI structure or another periodic variation can be separated from the active region but associated therewith. For example, a QW or MQW structure which overlies the active region will carry the evanescent part of the waveform that is propagating in the active region. A periodic QWI structure in this region will thus affect the waveform.Type: ApplicationFiled: November 28, 2001Publication date: June 27, 2002Applicant: KAMELIAN LIMITEDInventors: Craig Tombling, Alistair Henderson Kean, Martin David Dawson, Anthony Edward Kelly
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Publication number: 20020015866Abstract: This invention relates to a method of growing a nitride semiconductor layer by molecular beam epitaxy comprising the steps of: a) heating a GaN substrate (S) disposed in a growth chamber (10) to a substrate temperature of at least 850° C.; and b) growing a nitride semiconductor layer on the GaN substrate by molecular beam epitaxy at a substrate temperature of at least 850° C., ammonia gas being supplied to the growth chamber (10) during the growth of the nitride semiconductor layer; wherein the method comprises the further step of commencing the supply ammonia gas to the growth chamber during step (a), before the substrate temperature has reached 800° C.Type: ApplicationFiled: June 18, 2001Publication date: February 7, 2002Inventors: Stewart Edward Hooper, Jonathan Heffernan, Jennifer Mary Barnes, Alistair Henderson Kean
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Patent number: 6146458Abstract: A method of growing a layer of Group III nitride material on a substrate by molecular beam epitaxy includes the steps of (i) disposing a substrate in a vacuum chamber, (ii) reducing the pressure in the vacuum chamber to a pressure suitable for epitaxial growth by molecular beam epitaxy, (iii) supplying ammonia through an outlet of a first supply conduit into the vacuum chamber so that the ammonia flows towards the substrate; and (iv) supplying a Group III element in elemental form through an outlet of a second supply conduit into the vacuum chamber so that said Group III element flows towards the substrate. The method causes a layer containing Group III nitride to be grown on the substrate by molecular beam epitaxy. In the method, the outlet of the first supply conduit is disposed nearer to the substrate than the outlet of the second supply conduit.Type: GrantFiled: March 12, 1998Date of Patent: November 14, 2000Assignee: Sharp Kabushiki KaishaInventors: Stewart Edward Hooper, Alistair Henderson Kean, Geoffrey Duggan