Patents by Inventor Rajesh D. Rajavel

Rajesh D. Rajavel 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: 9064992
    Abstract: A dual-band infrared detector structure based on Type-II superlattices (T2SL) has been developed and experimentally validated. The structure according to the principles of the present invention is designed for a single Indium bump architecture and utilizes a T2SL barrier design that omits the traditional p-n junction region. The barrier design comprises multiple periods where each period comprises multiple monolayers doped P type. By selecting the composition, number of monolayers per period and number of periods, a transition region is created in the conduction band between a first absorber layer and a second absorber layer that allows operation at low biases (<100 mV for both bands) and exhibits a dark current density in the longer wavelength band comparable to that obtained with single-color detectors.
    Type: Grant
    Filed: August 14, 2014
    Date of Patent: June 23, 2015
    Assignee: HRL Laboratories, LLC
    Inventors: Brett Z Nosho, Rajesh D Rajavel, Hasan Sharifi, Sevag Terterian
  • Patent number: 8969986
    Abstract: An infrared photo-detector with multiple discrete regions of a first absorber material. These regions may have geometric shapes with sloped sidewalls. The detector also may include a second absorber region comprising a second absorber material that absorbs light of a shorter wavelength than the light absorbed by the multiple discrete absorber regions of the first absorber material. The geometric shapes may extend only through the first absorber material. Alternatively, the geometric shapes may extend partially into the second absorber region. The detector has a metal reflector coupled to the multiple discrete absorber regions. The detector also has a substrate containing the discrete absorber regions and the second absorber region. The substrate can further include geometric shaped features etched into the substrate, with those features formed on the side of the substrate opposite the side containing the discrete absorber regions and the second absorber region.
    Type: Grant
    Filed: February 28, 2011
    Date of Patent: March 3, 2015
    Assignee: HRL Laboratories, LLC
    Inventors: Daniel Yap, Rajesh D. Rajavel, Sarabjit Mehta, Hasan Sharifi
  • Patent number: 8946839
    Abstract: An absorber is disclosed. The disclosed absorber contains a base layer, and a plurality of pillars disposed above the base layer and composed of material configured to absorb an incident light and generate minority electrical carriers and majority electrical carrier, wherein the height of the pillars is predetermined to provide a common pyramidal outline shared by the pillars in the plurality of pillars.
    Type: Grant
    Filed: August 20, 2009
    Date of Patent: February 3, 2015
    Assignee: HRL Laboratories, LLC
    Inventors: Daniel Yap, Rajesh D. Rajavel, Sarabjit Mehta, James H. Schaffner
  • Publication number: 20150014537
    Abstract: A dual-band infrared detector is provided. The dual-band infrared detector includes a first absorption layer, a barrier layer coupled to the first absorption layer, and a second absorption layer coupled to the barrier layer. The first absorption layer is sensitive to only a first infrared wavelength band and the second absorption layer is sensitive to only a second infrared wavelength band that is different from the first infrared wavelength band. The dual-band infrared detector is capable of detecting the first wavelength band and the second wavelength band by applying a first bias voltage of a first polarity to the first absorption layer and by applying a second bias voltage of a second polarity that is opposite the first polarity to the second absorption layer, wherein the first bias voltage and the second bias voltage each have a magnitude of less than about 500 mV.
    Type: Application
    Filed: July 15, 2013
    Publication date: January 15, 2015
    Inventors: Rajesh D. Rajavel, Terence J. deLyon
  • Patent number: 8900896
    Abstract: Fabrication of a photonic integrated circuit (PIC) including active elements such as a semiconductor optical amplifier (SOA) and passive elements such as a floating rib waveguide. Selective area doping through ion implantation or thermal diffusion before semiconductor epitaxial growth is used in order to define the contact and lateral current transport layers for each active device, while leaving areas corresponding to the passive devices undoped. InP wafers are used as the substrate which may be selectively doped with silicon.
    Type: Grant
    Filed: February 17, 2011
    Date of Patent: December 2, 2014
    Assignee: HRL Laboratories, LLC
    Inventors: Yakov Royter, Rajesh D. Rajavel, Irina Ionova, Sophi Ionova
  • Patent number: 8847202
    Abstract: A dual-band infrared detector structure based on Type-II superlattices (T2SL) has been developed and experimentally validated. The structure according to the principles of the present invention is designed for a single Indium bump architecture and utilizes a T2SL barrier design that omits the traditional p-n junction region. The barrier design comprises multiple periods where each period comprises multiple monolayers doped P type. By selecting the composition, number of monolayers per period and number of periods, a transition region is created in the conduction band between a first absorber layer and a second absorber layer that allows operation at low biases (<100 mV for both bands) and exhibits a dark current density in the longer wavelength band comparable to that obtained with single-color detectors.
    Type: Grant
    Filed: January 17, 2012
    Date of Patent: September 30, 2014
    Assignee: HRL Laboratories, LLC
    Inventors: Brett Z. Nosho, Rajesh D. Rajavel, Hasan Sharifi, Sevag Terterian
  • Patent number: 8835979
    Abstract: Using a multiple layer, varied composition barrier layer in place of the typical single layer barrier layer of an infrared photodetector results in a device with increased sensitivity and reduced dark current. A first barrier is adjacent the semiconductor contact; a second barrier layer is between the first barrier layer and the absorber layer. The barrier layers may be doped N type or P type with Beryllium, Carbon, Silicon or Tellurium. The energy bandgap is designed to facilitate minority carrier current flow in the contact region and block minority current flow outside the contact region.
    Type: Grant
    Filed: June 3, 2011
    Date of Patent: September 16, 2014
    Assignee: HRL Laboratories, LLC
    Inventors: Terence J De Lyon, Rajesh D Rajavel, Hasan Sharifi
  • Patent number: 8692295
    Abstract: A double heterojunction bipolar transistor on a substrate comprises a collector formed of InGaAsP, a base in contact with the collector, an emitter in contact with the base, and electrodes forming separate electrical contacts with each of the collector, base, and emitter, respectively. A device incorporates this transistor and an opto-electronic device optically coupled with the collector of the transistor to interact with light transmitted therethrough.
    Type: Grant
    Filed: September 25, 2009
    Date of Patent: April 8, 2014
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, Stephen Thomas, III
  • Patent number: 8093559
    Abstract: The present invention provides a two-terminal infrared detector capable of detecting a plurality of bands, such as three bands, over the visible and short-wave infrared bands. Detection of three colors enables one to construct composite imagery that provide significantly added contract in comparison to typical grayscale images. In some variations, the device includes multiple absorber and barrier layers that consist of distinct engineered semiconductor alloys which are closely lattice matched to InP.
    Type: Grant
    Filed: December 2, 2008
    Date of Patent: January 10, 2012
    Assignee: HRL Laboratories, LLC
    Inventor: Rajesh D. Rajavel
  • Patent number: 7932512
    Abstract: Fabrication of a photonic integrated circuit (PIC) including active elements such as a semiconductor optical amplifier (SOA) and passive elements such as a floating rib waveguide. Selective area doping through ion implantation or thermal diffusion before semiconductor epitaxial growth is used in order to define the contact and lateral current transport layers for each active device, while leaving areas corresponding to the passive devices undoped. InP wafers are used as the substrate which may be selectively doped with silicon.
    Type: Grant
    Filed: September 27, 2006
    Date of Patent: April 26, 2011
    Assignee: HRL Laboratories, LLC
    Inventors: Yakov I. Royter, Rajesh D. Rajavel, Stanislav I. Ionov, Irina Ionova, legal representative, Sophi Ionova, legal representative
  • Patent number: 7928389
    Abstract: An apparatus and method for a detector are disclosed. The apparatus disclosed contains an extractor layer, an absorber layer disposed adjacent to the extractor layer, a first electrical contact and a second electrical contact. The absorber layer is configured to absorb photons of incident light and generate minority electrical carriers and majority electrical carriers. In the disclosed apparatus, the top surface of the absorber layer is shaped as a pyramid, the extractor layer is electrically connected with the absorber layer and with the first electrical contact for extracting the minority electrical carriers, and the absorber layer is electrically connected with the extractor layer and with the second electrical contact to extract the majority electrical carriers.
    Type: Grant
    Filed: August 20, 2009
    Date of Patent: April 19, 2011
    Assignee: HRL Laboratories, LLC
    Inventors: Daniel Yap, Rajesh D. Rajavel, Sarabjit Mehta, Joseph S. Colburn
  • Patent number: 7800067
    Abstract: Electronically tunable and reconfigurable hyperspectral IR detectors and methods for making the same are presented. In one embodiment, a reconfigurable hyperspectral sensor (or detector) detects radiation from about 0.4 ?m to about 2 ?m and beyond. This sensor is configured to be compact, and lightweight and offers hyperspectral imaging capability while providing wavelength agility and tunability at the chip-level. That is, the sensor is used to rapidly image across diverse terrain to identify man-made objects and other anomalies in cluttered environments.
    Type: Grant
    Filed: December 1, 2009
    Date of Patent: September 21, 2010
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, David H. Chow, Andrew T. Hunter
  • Patent number: 7755023
    Abstract: Electronically tunable and reconfigurable hyperspectral IR detectors and methods for making the same are presented. In one embodiment, a reconfigurable hyperspectral sensor (or detector) detects radiation from about 0.4 ?m to about 2 ?m and beyond. This sensor is configured to be compact, and lightweight and offers hyperspectral imaging capability while providing wavelength agility and tunability at the chip-level. That is, the sensor is used to rapidly image across diverse terrain to identify man-made objects and other anomalies in cluttered environments.
    Type: Grant
    Filed: October 9, 2007
    Date of Patent: July 13, 2010
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, David H. Chow, Andrew T. Hunter
  • Patent number: 7692212
    Abstract: A double heterojunction bipolar transistor on a substrate comprises a collector formed of InGaAsP, a base in contact with the collector, an emitter in contact with the base, and electrodes forming separate electrical contacts with each of the collector, base, and emitter, respectively. A device incorporates this transistor and an opto-electronic device optically coupled with the collector of the transistor to interact with light transmitted therethrough.
    Type: Grant
    Filed: December 7, 2004
    Date of Patent: April 6, 2010
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, Stephen Thomas, III
  • Patent number: 7652252
    Abstract: Electronically tunable and reconfigurable hyperspectral IR detectors and methods for making the same are presented. In one embodiment, a reconfigurable hyperspectral sensor (or detector) detects radiation from about 0.4 ?m to about 2 ?m and beyond. This sensor is configured to be compact, and lightweight and offers hyperspectral imaging capability while providing wavelength agility and tunability at the chip-level. That is, the sensor is used to rapidly image across diverse terrain to identify man-made objects and other anomalies in cluttered environments.
    Type: Grant
    Filed: October 8, 2007
    Date of Patent: January 26, 2010
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, David H. Chow, Andrew T. Hunter
  • Patent number: 7582536
    Abstract: An electronic device contains a substrate, a sub-collector supported by the substrate, an un-doped layer having a selectively implanted buried sub-collector and supported by the sub-collector, an As-based nucleation layer partially supported by the un-doped layer, a collector layer supported by the As-based nucleation layer, a base layer supported by the collector layer, an emitter layer and a base contact supported by the base layer, an emitter cap layer supported by the emitter layer, an emitter contact supported by the emitter cap layer, and a collector contact supported by the sub-collector. A method provides for selecting a first InP layer, forming an As-based nucleation layer on the first InP layer, and epitaxially growing a second InP layer on the As-based nucleation layer.
    Type: Grant
    Filed: August 14, 2008
    Date of Patent: September 1, 2009
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, Mary Y. Chen, Steven S. Bui, David H. Chow, James Chingwei Li, Mehran Mokhtari, Marko Sokolich
  • Patent number: 7569872
    Abstract: Bipolar junction transistors (BJTs) and single or double heterojunction bipolar transistors with low parasitics, and methods for making the same is presented. A transistor is fabricated such that the collector region underneath a base contact area is deactivated. This results in a drastic reduction of the base-collector parasitic capacitance, Cbc. An embodiment of the present invention provides a transistor architecture for which the base contact area can be decoupled from the collector and hence allows for dramatic reduction in the parasitics of transistors.
    Type: Grant
    Filed: December 20, 2005
    Date of Patent: August 4, 2009
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, David H. Chow, Tahir Hussain, Yakov Royter
  • Patent number: 7531851
    Abstract: An electronic device contains a substrate, a sub-collector supported by the substrate, an un-doped layer having a selectively implanted buried sub-collector and supported by the sub-collector, an As-based nucleation layer partially supported by the un-doped layer, a collector layer supported by the As-based nucleation layer, a base layer supported by the collector layer, an emitter layer and a base contact supported by the base layer, an emitter cap layer supported by the emitter layer, an emitter contact supported by the emitter cap layer, and a collector contact supported by the sub-collector. A method provides for selecting a first InP layer, forming an As-based nucleation layer on the first InP layer, and epitaxially growing a second InP layer on the As-based nucleation layer.
    Type: Grant
    Filed: February 28, 2007
    Date of Patent: May 12, 2009
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, Mary Y. Chen, Steven S. Bui, David H. Chow, James Chingwei Li, Mehran Mokhtari, Marko Sokolich
  • Patent number: 7372084
    Abstract: Low power double heterojunction bipolar transistors with low parasitics, and methods for making the same is presented. A transistor is fabricated such that the collector region underneath a base contact area is deactivated. This results in a drastic reduction of the base-collector parasitic capacitance, Cbc. An embodiment of the present invention provides a transistor architecture for which the base contact area can be decoupled from the collector and hence allows for dramatic reduction in the parasitics of transistors.
    Type: Grant
    Filed: December 20, 2005
    Date of Patent: May 13, 2008
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, Kenneth Elliott, David H. Chow
  • Patent number: 7368765
    Abstract: Bipolar junction transistors (BJTs) and single or double heterojunction bipolar transistors with low parasitics, and methods for making the same is presented. A transistor is fabricated such that the collector region underneath a base contact area is deactivated. This results in a drastic reduction of the base-collector parasitic capacitance, Cbc. An embodiment of the present invention provides a transistor architecture for which the base contact area can be decoupled from the collector and hence allows for dramatic reduction in the parasitics of transistors.
    Type: Grant
    Filed: December 20, 2005
    Date of Patent: May 6, 2008
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, David H. Chow, Tahir Hussain, Yakov Royter