Patents by Inventor Ashish Tandon

Ashish Tandon 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: 7358523
    Abstract: Subwells are added to quantum wells of light emitting semiconductor structures to shift their emission wavelengths to longer wavelengths. Typical applications of the invention are to InGaAs, InGaAsSb, InP and GaN material systems, for example.
    Type: Grant
    Filed: October 20, 2004
    Date of Patent: April 15, 2008
    Assignee: Avago Technologies Fiber IP Pte Ltd
    Inventors: Michael R. T. Tan, Ashish Tandon, David P. Bour
  • Publication number: 20070289853
    Abstract: Embodiments of the invention provide for improved separation of switching material by creating a diversion of the activating force. In one embodiment at least one structural element is positioned in close proximity to an inlet for the actuating force to influence the actuating force to fully separate the switching material. Structural elements may include protrusions, either adjacent to the inlet or approximately across the channel from the inlet, as well as at least one additional inlet. The diversion can be created, if desired, by forces coming from opposite sides. Embodiments of the invention make use of non-wettable surfaces lining the channel in regions where switching material is to break into separate volumes, and wettable surfaces away from such regions. Embodiments of the invention provide for multi-pole, multi-throw switching.
    Type: Application
    Filed: June 14, 2006
    Publication date: December 20, 2007
    Inventors: Timothy Beerling, Ashish Tandon, Atul Goel
  • Patent number: 7269196
    Abstract: The method comprises forming barrier layers of AlxGa1-xAs, forming a quantum well layer of InGaAs between the barrier layers, and forming an interfacial layer between the quantum well layer and each of the barrier layers.
    Type: Grant
    Filed: July 6, 2004
    Date of Patent: September 11, 2007
    Assignee: Avago Technologies Fiber IP (Singapore) Pte. Ltd.
    Inventors: Ashish Tandon, Michael R. T. Tan, Ying-Lan Chang
  • Publication number: 20060279828
    Abstract: Double well structures in electro-absorption modulators are created in quantum well active regions by embedding deep ultra thin quantum wells. The perturbation introduced by the embedded, deep ultra thin quantum well centered within a conventional quantum well lowers the confined energy state for the wavefunction in the surrounding larger well and typically results in the hole and electron distributions being more confined to the center of the conventional quantum well. The extinction ratio provided by the electro-absorption modulator is typically increased.
    Type: Application
    Filed: June 8, 2005
    Publication date: December 14, 2006
    Inventors: David Bour, Ashish Tandon, Michael Tan
  • Publication number: 20060274801
    Abstract: In accordance with the invention, increased maximum modulation speeds and improved hole distribution are obtained for light emitting devices. Barrier layers of a quantum well structure for a light emitting device are formed with varying barrier energy heights. Quantum well layers of the quantum well structure are formed between the barrier layers.
    Type: Application
    Filed: June 1, 2005
    Publication date: December 7, 2006
    Inventors: Ashish Tandon, Kostadin Djordjev, Chao-Kun Lin, Michael Tan
  • Patent number: 7142342
    Abstract: The electroabsorption modulator comprises a p-i-n junction structure that includes an active layer, a p-type cladding layer and an n-type cladding layer with the active layer sandwiched between the cladding layers. The electroabsorption modulator additionally comprises a quantum well structure located within the active layer. The p-type cladding layer comprises a layer of heavily-doped low-diffusivity p-type semiconductor material located adjacent the active layer that reduces the extension of the depletion region into the p-type cladding layer when a reverse bias is applied to the electroabsorption modulator. The reduced extension increases the strength of the electric field applied to the quantum well structure by a given reverse bias voltage. The increased field strength increases the extinction ratio of the electroabsorption modulator.
    Type: Grant
    Filed: June 2, 2003
    Date of Patent: November 28, 2006
    Assignee: Avago Technologies Fiber IP (Singapore) Pte. Ltd.
    Inventors: David P. Bour, Ashish Tandon, Scott W. Corzine, Chaokun Lin
  • Patent number: 7033938
    Abstract: The active region of a long-wavelength light emitting device is made by providing an organometallic vapor phase epitaxy (OMVPE) reactor, placing a substrate wafer capable of supporting growth of indium gallium arsenide nitride in the reactor, supplying a Group III–V precursor mixture comprising an arsenic precursor, a nitrogen precursor, a gallium precursor, an indium precursor and a carrier gas to the reactor and pressurizing the reactor to a sub-atmospheric elevated growth pressure no higher than that at which a layer of indium gallium arsenide layer having a nitrogen fraction commensurate with light emission at a wavelength longer than 1.2 ?m is deposited over the substrate wafer.
    Type: Grant
    Filed: February 23, 2004
    Date of Patent: April 25, 2006
    Inventors: David P. Bour, Tetsuya Takeuchi, Ashish Tandon, Ying-Lan Chang, Michael R. T. Tan, Scott W. Corzine
  • Patent number: 7034331
    Abstract: The tunnel junction structure comprises a p-type tunnel junction layer of a first semiconductor material, an n-type tunnel junction layer of a second semiconductor material and a tunnel junction between the tunnel junction layers. At least one of the semiconductor materials includes gallium (Ga), arsenic (As) and either nitrogen (N) or antimony (Sb). The probability of tunneling is significantly increased, and the voltage drop across the tunnel junction is consequently decreased, by forming the tunnel junction structure of materials having a reduced difference between the valence band energy of the material of the p-type tunnel junction layer and the conduction band energy of the n-type tunnel junction layer.
    Type: Grant
    Filed: June 4, 2004
    Date of Patent: April 25, 2006
    Assignee: Agilent Technologies, Inc.
    Inventors: Ying-Lan Chang, Ashish Tandon, Michael H. Leary, Michael R. T. Tan
  • Publication number: 20060083278
    Abstract: Subwells are added to quantum wells of light emitting semiconductor structures to shift their emission wavelengths to longer wavelengths. Typical applications of the invention are to InGaAs, InGaAsSb, InP and GaN material systems, for example.
    Type: Application
    Filed: October 20, 2004
    Publication date: April 20, 2006
    Inventors: Michael Tan, Ashish Tandon, David Bour
  • Patent number: 7016392
    Abstract: The light-emitting device comprises a substrate, an active region and a tunnel junction structure. The substrate comprises gallium arsenide. The active region comprises an n-type spacing layer and a p-type spacing layer. The tunnel junction structure comprises a p-type tunnel junction layer adjacent the p-type spacing layer, an n-type tunnel junction layer and a tunnel junction between the p-type tunnel junction layer and the n-type tunnel junction layer. The p-type tunnel junction layer comprises a layer of a p-type first semiconductor material that includes gallium and arsenic. The n-type tunnel junction layer comprises a layer of an n-type second semiconductor material that includes indium, gallium and phosphorus. The high dopant concentration attainable in the second semiconductor material reduces the width of the depletion region at the tunnel junction and increases the electrostatic field across the tunnel junction, so that the reverse bias at which tunneling occurs is reduced.
    Type: Grant
    Filed: April 30, 2003
    Date of Patent: March 21, 2006
    Inventors: Ashish Tandon, Michael H. Leary, Ying-Lan Chang
  • Publication number: 20060007974
    Abstract: The method comprises forming barrier layers of AlxGa1-xAs, forming a quantum well layer of InGaAs between the barrier layers, and forming an interfacial layer between the quantum well layer and each of the barrier layers.
    Type: Application
    Filed: July 6, 2004
    Publication date: January 12, 2006
    Inventors: Ashish Tandon, Michael Tan, Ying-Lan Chang
  • Publication number: 20050184303
    Abstract: A strain compensating structure comprises a strain compensating layer adjacent an oxide-forming layer. The strain compensating layer compensates for the change in the lattice parameter due to oxidation of at least part of the oxide-forming layer.
    Type: Application
    Filed: February 25, 2004
    Publication date: August 25, 2005
    Inventors: Ashish Tandon, Michael Leary, Michael Tan, Ying-Lan Chang
  • Patent number: 6876686
    Abstract: A laser and method for making the same are disclosed. The laser includes a p-layer, an n-layer, and an active region located between the p-layer and the n-layer. The active region includes a quantum well layer sandwiched between first and second barrier layers. The quantum well layer includes an InP-based material. The first and second barrier layers also include an InP-based material. The barrier layers are homogeneous layers of the InP-based material. The barrier layers are preferably deposited by chemical vapor deposition from precursors that include a surfactant element that inhibits the formation of P—P dimers on a surface of the barrier layer during the deposition process. In one embodiment, the surfactant element is chosen from the group consisting of Sb, Si, and Te, and the barrier material includes InGaP or AlInP.
    Type: Grant
    Filed: February 24, 2003
    Date of Patent: April 5, 2005
    Assignee: Agilent Technologies, Inc.
    Inventors: Ashish Tandon, Ying-Lan Chang
  • Publication number: 20040240025
    Abstract: The electroabsorption modulator comprises a p-i-n junction structure that includes an active layer, a p-type cladding layer and an n-type cladding layer with the active layer sandwiched between the cladding layers. The electroabsorption modulator additionally comprises a quantum well structure located within the active layer. The p-type cladding layer comprises a layer of heavily-doped low-diffusivity p-type semiconductor material located adjacent the active layer that reduces the extension of the depletion region into the p-type cladding layer when a reverse bias is applied to the electroabsorption modulator. The reduced extension increases the strength of the electric field applied to the quantum well structure by a given reverse bias voltage. The increased field strength increases the extinction ratio of the electroabsorption modulator.
    Type: Application
    Filed: June 2, 2003
    Publication date: December 2, 2004
    Inventors: David P. Bour, Ashish Tandon, Scott W. Corzine, Chaokun Lin
  • Publication number: 20040219703
    Abstract: The active region of a long-wavelength light emitting device is made by providing an organometallic vapor phase epitaxy (OMVPE) reactor, placing a substrate wafer capable of supporting growth of indium gallium arsenide nitride in the reactor, supplying a Group III-V precursor mixture comprising an arsenic precursor, a nitrogen precursor, a gallium precursor, an indium precursor and a carrier gas to the reactor and pressurizing the reactor to a sub-atmospheric elevated growth pressure no higher than that at which a layer of indium gallium arsenide layer having a nitrogen fraction commensurate with light emission at a wavelength longer than 1.2 &mgr;m is deposited over the substrate wafer.
    Type: Application
    Filed: February 23, 2004
    Publication date: November 4, 2004
    Inventors: David P. Bour, Tetsuya Takeuchi, Ashish Tandon, Ying-Lan Chang, Michael R. T. Tan, Scott W. Corzine
  • Publication number: 20040217343
    Abstract: The tunnel junction structure comprises a p-type tunnel junction layer of a first semiconductor material, an n-type tunnel junction layer of a second semiconductor material and a tunnel junction between the tunnel junction layers. At least one of the semiconductor materials includes gallium (Ga), arsenic (As) and either nitrogen (N) or antimony (Sb). The probability of tunneling is significantly increased, and the voltage drop across the tunnel junction is consequently decreased, by forming the tunnel junction structure of materials having a reduced difference between the valence band energy of the material of the p-type tunnel junction layer and the conduction band energy of the n-type tunnel junction layer.
    Type: Application
    Filed: June 4, 2004
    Publication date: November 4, 2004
    Inventors: Ying-Lan Chang, Ashish Tandon, Michael H. Leary, Michael R. T. Tan
  • Publication number: 20040218655
    Abstract: The light-emitting device comprises a substrate, an active region and a tunnel junction structure. The substrate comprises gallium arsenide. The active region comprises an n-type spacing layer and a p-type spacing layer. The tunnel junction structure comprises a p-type tunnel junction layer adjacent the p-type spacing layer, an n-type tunnel junction layer and a tunnel junction between the p-type tunnel junction layer and the n-type tunnel junction layer. The p-type tunnel junction layer comprises a layer of a p-type first semiconductor material that includes gallium and arsenic. The n-type tunnel junction layer comprises a layer of an n-type second semiconductor material that includes indium, gallium and phosphorus. The high dopant concentration attainable in the second semiconductor material reduces the width of the depletion region at the tunnel junction and increases the electrostatic field across the tunnel junction, so that the reverse bias at which tunneling occurs is reduced.
    Type: Application
    Filed: April 30, 2003
    Publication date: November 4, 2004
    Inventors: Ashish Tandon, Michael H. Leary, Ying-Lan Chang
  • Publication number: 20040165631
    Abstract: A laser and method for making the same are disclosed. The laser includes a p-layer, an n-layer, and an active region located between the p-layer and the n-layer. The active region includes a quantum well layer sandwiched between first and second barrier layers. The quantum well layer includes an InP-based material. The first and second barrier layers also include an InP-based material. The barrier layers are homogeneous layers of the InP-based material. The barrier layers are preferably deposited by chemical vapor deposition from precursors that include a surfactant element that inhibits the formation of P-P dimers on a surface of the barrier layer during the deposition process. In one embodiment, the surfactant element is chosen from the group consisting of Sb, Si, and Te, and the barrier material includes InGaP or AlInP.
    Type: Application
    Filed: February 24, 2003
    Publication date: August 26, 2004
    Inventors: Ashish Tandon, Ying-Lan Chang
  • Patent number: 6765238
    Abstract: The tunnel junction structure comprises a p-type tunnel junction layer of a first semiconductor material, an n-type tunnel junction layer of a second semiconductor material and a tunnel junction between the tunnel junction layers. At least one of the semiconductor materials includes gallium (Ga), arsenic (As) and either nitrogen (N) or antimony (Sb). The probability of tunneling is significantly increased, and the voltage drop across the tunnel junction is consequently decreased, by forming the tunnel junction structure of materials having a reduced difference between the valence band energy of the material of the p-type tunnel junction layer and the conduction band energy of the n-type tunnel junction layer.
    Type: Grant
    Filed: September 12, 2002
    Date of Patent: July 20, 2004
    Assignee: Agilent Technologies, Inc.
    Inventors: Yin-Lan Chang, Ashish Tandon, Michael H. Leary, Michael R. T. Tan
  • Patent number: 6756325
    Abstract: Several methods for producing an active region for a long wavelength light emitting device are disclosed. In one embodiment, the method comprises placing a substrate in an organometallic vapor phase epitaxy (OMVPE) reactor, the substrate for supporting growth of an indium gallium arsenide nitride (InGaAsN) film, supplying to the reactor a group-III-V precursor mixture comprising arsine, dimethylhydrazine, alkyl-gallium, alkyl-indium and a carrier gas, where the arsine and the dimethylhydrazine are the group-V precursor materials and where the percentage of dimethylhydrazine substantially exceeds the percentage of arsine, and pressurizing the reactor to a pressure at which a concentration of nitrogen commensurate with light emission at a wavelength longer than 1.2 um is extracted from the dimethylhydrazine and deposited on the substrate.
    Type: Grant
    Filed: May 7, 2002
    Date of Patent: June 29, 2004
    Assignee: Agilent Technologies, Inc.
    Inventors: David P. Bour, Tetsuya Takeuchi, Ashish Tandon, Ying-Lan Chang, Michael R. T. Tan, Scott Corzine