Patents by Inventor Supratik Guha

Supratik Guha 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: 6255671
    Abstract: A structure includes a metal nitride film of the form MN, where M is selected from the group consisting of Ga, In, AlGa, AlIn, and AlGaIn. The structure has at least one electrically conductive metal region that is formed within and from the metal nitride film by a thermal process driven by absorption of light having a predetermined wavelength. Single films comprised of AlN are also within the scope of this invention, wherein an Al trace or interconnect is formed by laser radiation of wavelength 248 nm so as to contact circuitry that exists under the film. Multilayered stacks of films are also within the scope of the teachings of this invention.
    Type: Grant
    Filed: January 5, 1998
    Date of Patent: July 3, 2001
    Assignee: International Business Machines Corporation
    Inventors: Nestor Alexander Bojarczuk, Jr., Supratik Guha, Arunava Gupta, Sampath Purushothaman
  • Patent number: 6210479
    Abstract: A process for cheaply fabricating a substantially single crystal or a polycrystalline semiconductor structure on a host substrate. The process begins by depositing a layer of wide band gap nitride material 10, such as gallium nitride, aluminum nitride and/or indium nitride, on a sapphire substrate 11. The semiconductor structure 14 is then grown on the nitride layer. Next, the host substrate 15 is attached with a bonding agent to an exposed surface area of the semiconductor structure 14. The sapphire substrate is lifted off by irradiation in which nitrogen is dissociated from the nitride layer.
    Type: Grant
    Filed: February 26, 1999
    Date of Patent: April 3, 2001
    Assignee: International Business Machines Corporation
    Inventors: Nestor A. Bojarczuk, Supratik Guha, Arunava Gupta
  • Patent number: 6146755
    Abstract: A storage device and a method of forming a storage device, includes depositing a metal layer on a substrate, and oxidizing the metal layer to form an oxide with a rutile structure on which a ferromagnetic material is selectively grown. The substrate may be substantially formed of either SiO.sub.2, Si.sub.3 N.sub.4, or a compound of SiO.sub.2 and Si.sub.3 N.sub.4. In another method, a method of forming a magnetic device, includes one of seeding a surface with one of Ti, Sn, and Ru islands having nanometer dimensions, and by exposing nanometer scale areas of the one of Ti, Sn, and Ru on a substrate, and coating the one of Ti, Sn, and Ru, with a ferromagnetic material. The surface may be substantially formed of either SiO.sub.2, Si.sub.3 N.sub.4, or a compound of SiO.sub.2 and Si.sub.3 N.sub.4. Similarly, the substrate may be substantially formed of either SiO.sub.2, Si.sub.3 N.sub.4, or a compound of SiO.sub.2 and Si.sub.3 N.sub.4.
    Type: Grant
    Filed: October 15, 1998
    Date of Patent: November 14, 2000
    Assignee: International Business Machines Corporation
    Inventors: Supratik Guha, Arunava Gupta
  • Patent number: 6120909
    Abstract: A color display device which may be used as a gallium nitride (LED) light emitting diode based traffic light is disclosed. Unlike previous large GaN based display devices, which have been built up from numerous small display elements formed on sapphire substrates, the disclosed device preferably uses an entire monolithic silicon wafer as both a substrate and for connection as a whole as a conducting first electrode, a light emitting layered structure of GaN-based materials over the entire monolithic silicon substrate, and a substantially transparent metallic second electrode layer over the layered structure. In order to emit desired traffic light colors (e.g. yellow, red), a color conversion layer is disposed over the transparent metallic electrode layer.
    Type: Grant
    Filed: August 19, 1998
    Date of Patent: September 19, 2000
    Assignee: International Business Machines Corporation
    Inventors: Nestor A. Bojarczuk, Jr., Supratik Guha, Richard Alan Haight
  • Patent number: 5898185
    Abstract: This invention provides a novel hybrid organic-inorganic semiconductor light emitting diode. The device consists of an electroluminescent layer and a photoluminescent layer. The electroluminescent layer is an inorganic GaN light emitting diode structure that is electroluminescent in the blue or ultraviolet (uv) region of the electromagnetic spectrum when the device is operated. The photoluminescent layer is a photoluminescent organic thin film such as tris-(8-hydroxyquinoline) Al, Alq3, deposited onto the GaN LED and which has a high photoluminescence efficiency. The uv emission from the electroluminescent region excites the Alq3 which photoluminesces in the green. Such a photoconversion results in a light emitting diode that operates in the green (in the visible range). Other colors such as blue or red may be obtained by appropriately doping the Alq3. Furthermore, other luminescent organics in addition to Alq3 may be used to directly convert the uv or blue to other wavelengths of interest.
    Type: Grant
    Filed: January 24, 1997
    Date of Patent: April 27, 1999
    Assignee: International Business Machines Corporation
    Inventors: Nestor A. Bojarczuk, Jr., Supratik Guha, Richard Alan Haight
  • Patent number: 5895932
    Abstract: This invention provides a novel hybrid organic-inorganic semiconductor light emitting diode. The device consists of an electroluminescent layer and a photoluminescent layer. The electroluminescent layer is an inorganic GaN light emitting diode structure that is electroluminescent in the blue or ultraviolet (uv) region of the electromagnetic spectrum when the device is operated. The photoluminescent layer is a photoluminescent organic thin film such as tris-(8-hydroxyquinoline) Al, Alq3, deposited onto the GaN LED and which has a high photoluminescence efficiency. The uv emission from the electroluminescent region excites the Alq3 which photoluminesces in the green. Such a photoconversion results in a light emitting diode that operates in the green (in the visible range). Other colors such as blue or red may be obtained by appropriately doping the Alq3. Furthermore, other luminescent organics in addition to Alq3 may be used to directly convert the uv or blue to other wavelengths of interest.
    Type: Grant
    Filed: March 5, 1997
    Date of Patent: April 20, 1999
    Assignee: International Business Machines Corporation
    Inventors: Nestor A. Bojarczuk, Jr., Supratik Guha, Richard Alan Haight
  • Patent number: 5879962
    Abstract: A method for repeatably fabricating GaAs/ZnSe and other III-V/II-VI semiconductor interfaces with relatively low stacking fault densities in II-VI semiconductor devices such as laser diodes. The method includes providing a molecular beam epitaxy (MBE) system including at least a group III element source, a group II element source, a group V element source and a group VI element source. A semiconductor substrate having a III-V semiconductor surface on which the interface is to be fabricated is positioned within the MBE system. The substrate is then heated to a temperature suitable for III-V semiconductor growth, and a crystalline III-V semiconductor buffer layer grown on the III-V surface of the substrate. The temperature of the semiconductor substrate is then adjusted to a temperature suitable for II-VI semiconductor growth, and a crystalline II-VI semiconductor buffer layer grown on the III-V buffer layer by alternating beam epitaxy.
    Type: Grant
    Filed: December 13, 1995
    Date of Patent: March 9, 1999
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: James M. DePuydt, Michael A. Haase, Kwok-Keung Law, Thomas J. Miller, James M. Gaines, Supratik Guha, Bor-Jen Wu
  • Patent number: 5874147
    Abstract: This invention provides phase change media for optical storage based on semiconductors of nitrides of the column III metals. The surface of thin films of these wide bandgap semiconductors may be metallized (by desorption of the nitrogen) by irradiating with photons of energy equal to, or greater than the band gap of these materials, and with power densities beyond a critical threshold value. As a consequence of such writable metallization, these materials are excellent candidates for write once, read many times storage media since the differences in the reflectivity between the metal and its corresponding wide gap nitride are very large. Furthermore, once the nitrogen is desorbed, the written metallic phase can no longer revert back to the nitride phase and hence the media is stable and is truly a write-once system.
    Type: Grant
    Filed: July 15, 1997
    Date of Patent: February 23, 1999
    Assignee: International Business Machines Corporation
    Inventors: Nestor Alexander Bojarczuk, Jr., Supratik Guha, Arunava Gupta, Wade Wai-Chung Tang
  • Patent number: 5739545
    Abstract: Organic light emitting diodes having a transparent cathode structure is disclosed. The structure consists of a low work function metal in direct contact with the electron transport layer of the OLED covered by a layer of a wide bandgap semiconductor. Calcium is the preferred metal because of its relatively high optical transmissivity for a metal and because of its proven ability to form a good electron injecting contact to organic materials. ZnSe, ZnS or an alloy of these materials are the preferred semiconductors because of their good conductivity parallel to the direction of light emission, their ability to protect the underlying low work function metal and organic films and their transparency to the emitted light. Arrays of these diodes, appropriately wired, can be used to make a self-emissive display. When fabricated on a transparent substrate, such a display is at least partially transparent making it useful for heads-up display applications in airplanes and automobiles.
    Type: Grant
    Filed: February 4, 1997
    Date of Patent: April 14, 1998
    Assignee: International Business Machines Corporation
    Inventors: Supratik Guha, Richard Alan Haight, Joseph M. Karasinski, Ronald R. Troutman
  • Patent number: 5416337
    Abstract: The present invention is a hetero superlattice pn junction. In particular, the invention combines n and p type superlattices into a single pn junction having a bandgap sufficient to create high frequency (i.e. blue or higher) light emission. Individual superlattices are formed using a molecular beam epitaxy process. This process creates thin layers of well material separated by thin layers of barrier material. The well material is doped to create carrier concentrations and the barrier materials are chosen in combination with the thickness of the well materials to adjust the effective bandgap of the superlattice in order to create an effective wide bandgap material. The barrier material for the n and p type superlattices is different from the material used to form either of the two types of well layers.
    Type: Grant
    Filed: September 24, 1993
    Date of Patent: May 16, 1995
    Assignee: International Business Machines Corporation
    Inventors: Leroy L. Chang, Supratik Guha, Hiroo Munekata