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: 10424608
    Abstract: Methods of fabrication and monolithic integration of a polycrystalline infrared detector structure deposit Group III-V compound semiconductor materials at a low deposition temperature within a range of about 300° C. to about 400° C. directly on an amorphous template. The methods provide wafer-level fabrication of polycrystalline infrared detectors and monolithic integration with a readout integrated circuit wafer for focal plane arrays.
    Type: Grant
    Filed: January 31, 2018
    Date of Patent: September 24, 2019
    Assignee: HRL Laboratories, LLC
    Inventors: Terence J. DeLyon, Rajesh D. Rajavel, Sevag Terterian, Minh B. Nguyen, Hasan Sharifi
  • Patent number: 10361333
    Abstract: A detector. The detector includes a first collector, a first interface layer on the first collector, a first absorber on the first interface layer, a second interface layer on the first absorber, and a second collector on the second interface layer. The first absorber is configured to absorb photons to generate electron-hole pairs. The first interface layer may include a barrier configured to impede the flow of majority carriers from the first absorber to the first collector. The second barrier may include a barrier configured to impede the flow of majority carriers from the first absorber, or from a second absorber, to the second collector.
    Type: Grant
    Filed: August 11, 2016
    Date of Patent: July 23, 2019
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D. Rajavel, Hasan Sharifi, Terence J. DeLyon
  • Patent number: 10269996
    Abstract: A position sensitive detector includes a substrate, an absorber layer on the substrate, a barrier layer on the absorber layer, a contact layer on the barrier layer, and a first contact and a second contact on the contact layer. The barrier layer prevents a flow of majority carriers from the absorber layer to the contact layer. The position sensitive detector is sensitive to a lateral position between the first contact and the second contact of incident light on the contact layer.
    Type: Grant
    Filed: July 28, 2016
    Date of Patent: April 23, 2019
    Assignee: HRL Laboratories, LLC
    Inventors: Hasan Sharifi, Rajesh D. Rajavel, Terence J. De Lyon, Daniel Yap
  • Patent number: 9748427
    Abstract: The invention describes a device which enables MWIR photodetectors to operate at zero bias and deliver low dark current performance. The performance is achieved by incorporating a p-n junction in the barrier. The device consists of a p-type contact layer, a p-n junction in the compound barrier (CB) with graded composition and/or doping profiles, and an n-type absorber (p-CB-n) device.
    Type: Grant
    Filed: October 31, 2013
    Date of Patent: August 29, 2017
    Assignee: HRL Laboratories, LLC
    Inventors: Rajesh D Rajavel, Hasan Sharifi, Terence J De Lyon, Pierre-Yves Delaunay, Brett Z Nosho
  • Patent number: 9709711
    Abstract: A wavelength-selective optical diffuser comprising a substrate of a first material having opposite first and second surfaces, wherein said first material is transparent to a first wavelength ?S and a second wavelength ?L, with ?L>4?S; at least a first surface of said substrate having a surface relief such that a beam of light having the first wavelength ?S is diffused, with a rms phase delay S>?/4, when traversing said substrate; and a beam of light having the second wavelength ?L is minimally diffused, with a rms phase delay S<?/4, when traversing said substrate.
    Type: Grant
    Filed: September 18, 2013
    Date of Patent: July 18, 2017
    Assignees: HRL Laboratories, LLC, The Boeing Company
    Inventors: Daniel Yap, Hasan Sharifi, Don F. Weston, Rajesh D. Rajavel
  • Patent number: 9520525
    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: January 9, 2015
    Date of Patent: December 13, 2016
    Assignee: HRL Laboratories, LLC
    Inventors: Daniel Yap, Rajesh D. Rajavel, Sarabjit Mehta, Hasan Sharifi
  • Patent number: 9490292
    Abstract: An infrared photo-detector array and a method for manufacturing it are disclosed. The infrared photo-detector array contains a collector layer, a first absorber layer that absorbs incident light of a first wavelength band and generates first electrons and first holes, a second absorber layer that absorbs incident light of a second wavelength band and generates second electrons and second holes, and wherein the wavelengths of the incident light in the first wavelength band are shorter than the wavelengths of the incident light in the second wavelength band, and wherein the second absorber layer is laterally contiguous across at least two photo-detectors. The method disclosed teaches how to manufacture the infrared photo-detector array.
    Type: Grant
    Filed: March 14, 2014
    Date of Patent: November 8, 2016
    Assignee: HRL Laboratories, LLC
    Inventors: Daniel Yap, Rajesh D. Rajavel
  • Patent number: 9466746
    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: February 12, 2016
    Date of Patent: October 11, 2016
    Assignee: HRL Laboratories, LLC
    Inventors: Terence J De Lyon, Rajesh D Rajavel, Hasan Sharifi
  • Patent number: 9444001
    Abstract: A position sensitive detector includes a substrate, an absorber layer on the substrate, a barrier layer on the absorber layer, a contact layer on the barrier layer, and a first contact and a second contact on the contact layer. The barrier layer prevents a flow of majority carriers from the absorber layer to the contact layer. The position sensitive detector is sensitive to a lateral position between the first contact and the second contact of incident light on the contact layer.
    Type: Grant
    Filed: June 28, 2013
    Date of Patent: September 13, 2016
    Assignee: HRL Laboratories, LLC
    Inventors: Hasan Sharifi, Rajesh D. Rajavel, Terence J. De Lyon, Daniel Yap
  • Patent number: 9293612
    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: August 7, 2014
    Date of Patent: March 22, 2016
    Assignee: HRL Laboratories, LLC
    Inventors: Terence J De Lyon, Rajesh D Rajavel, Hasan Sharifi
  • Patent number: 9231137
    Abstract: Using a highly doped Cap layer of the same composition as the Contact material in an nBn or pBp infrared photodetector allows engineering of the energy band diagram to facilitate minority carrier current flow in the contact region and block minority current flow outside the Contact region. The heavily doped Cap layer is disposed on the Barrier between the Contacts but electrically isolated from the Contact material.
    Type: Grant
    Filed: June 3, 2011
    Date of Patent: January 5, 2016
    Assignee: HRL Laboratories, LLC
    Inventors: Hasan Sharifi, Terence J. De Lyon, Rajesh D. Rajavel
  • Patent number: 9207120
    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: Grant
    Filed: July 15, 2013
    Date of Patent: December 8, 2015
    Assignee: The Boeing Company
    Inventors: Rajesh D. Rajavel, Terence J. deLyon
  • 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