Patents by Inventor Rajaram Bhat

Rajaram Bhat 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: 8897329
    Abstract: Group III nitride-based laser diodes comprise an n-side cladding layer formed of n-doped (Al,In)GaN, an n-side waveguide layer formed of n-doped (Al)InGaN, an active region, a p-side waveguide layer formed of p-doped (Al)InGaN, and a p-side cladding layer formed of p-doped (Al,In)GaN. Optical mode is shifted away from high acceptor concentrations in p-type layers through manipulation of indium concentration and thickness of the n-side waveguide layer. Dopant and compositional profiles of the p-side cladding layer and the p-side waveguide layer are tailored to reduce optical loss and increased wall plug efficiency.
    Type: Grant
    Filed: September 20, 2010
    Date of Patent: November 25, 2014
    Assignee: Corning Incorporated
    Inventors: Dmitry Sizov, Rajaram Bhat, Chung-En Zah
  • Publication number: 20130329760
    Abstract: An embodiment of semiconductor laser comprising: (a) a GaN, AlGaN, InGaN, or AlN substrate; (b) an n-doped cladding layer situated over the substrate; (c) a p-doped cladding layer situated over the n-doped; (d) at least one active layer situated between the n-doped and the p-doped cladding layer, and at least one of said cladding layers comprises a superstructure structure of AlInGaN/GaN, AlInGaN/AlGaN, AlInGaN//InGaN or AlInGaN/AlN with the composition such that the total of lattice mismatch strain of the whole structure does not exceed 40 nm %.
    Type: Application
    Filed: February 2, 2012
    Publication date: December 12, 2013
    Inventors: Rajaram Bhat, Dmitry Sergeevich Sizov, Chung-En Zah
  • Publication number: 20130322481
    Abstract: Laser diodes and methods of fabricating laser diodes are disclosed. A laser diode includes a substrate including (Al,In)GaN, an n-side cladding layer including (Al,In)GaN having an n-type conductivity, an n-side waveguide layer including (Al,In)GaN having an n-type conductivity, an active region, a p-side waveguide layer including (Al,In)GaN having a p-type conductivity, a p-side cladding layer including (Al,In)GaN having a p-type conductivity, and a laser cavity formed by cleaved facets. The substrate includes a crystal structure having a surface plane orientation within about 10 degrees of a 20 23 or a 20 23 crystallographic plane orientation. The laser cavity is formed by cleaved facets that have an orientation corresponding to a nonpolar plane of the crystal structure of the substrate.
    Type: Application
    Filed: May 31, 2012
    Publication date: December 5, 2013
    Inventors: Rajaram Bhat, Dmitry Sergeevich Sizov, Chung-En Zah
  • Publication number: 20130044783
    Abstract: Light emitting devices are provided comprising an active region interposed between n-type and p-type sides of the device and a hole blocking layer interposed between the active region and the n-type side of the device. The active region comprises an active MQW structure and is configured for electrically-pumped stimulated emission of photons in the green portion of the optical spectrum. The n-type side of the light emitting device comprises an n-doped semiconductor region. The p-type side of the light emitting device comprises a p-doped semiconductor region. The n-doped semiconductor region comprises an n-doped non-polar or n-doped semi-polar substrate. Hole blocking layers according to the present disclosure comprise an n-doped semiconductor material and are interposed between the non-polar or semi-polar substrate and the active region of the light emitting device. The hole blocking layer (HBL) composition is characterized by a wider bandgap than that of the quantum well barrier layers of the active region.
    Type: Application
    Filed: August 16, 2011
    Publication date: February 21, 2013
    Inventors: Rajaram Bhat, Dmitry S. Sizov, Chung-En Zah
  • Patent number: 8379684
    Abstract: Light emitting devices are provided comprising an active region interposed between n-type and p-type sides of the device and a hole blocking layer interposed between the active region and the n-type side of the device. The active region comprises an active MQW structure and is configured for electrically-pumped stimulated emission of photons in the green portion of the optical spectrum. The n-type side of the light emitting device comprises an n-doped semiconductor region. The p-type side of the light emitting device comprises a p-doped semiconductor region. The n-doped semiconductor region comprises an n-doped non-polar or n-doped semi-polar substrate. Hole blocking layers according to the present disclosure comprise an n-doped semiconductor material and are interposed between the non-polar or semi-polar substrate and the active region of the light emitting device. The hole blocking layer (HBL) composition is characterized by a wider bandgap than that of the quantum well barrier layers of the active region.
    Type: Grant
    Filed: August 16, 2011
    Date of Patent: February 19, 2013
    Assignee: Corning Incorporated
    Inventors: Rajaram Bhat, Dmitry S. Sizov, Chung-En Zah
  • Patent number: 8358673
    Abstract: According to the concepts of the present disclosure, laser diode waveguide configurations are contemplated where the use of Al in the waveguide layers of the laser is presented in the form of InGaN/Al(In)GaN waveguiding superstructure comprising optical confining wells (InGaN) and strain compensating barriers (Al(In)GaN). The composition of the optical confining wells is chosen such that they provide strong optical confinement, even in the presence of the Al(In)GaN strain compensating barriers, but do not absorb lasing emission. The composition of the strain compensating barriers is chosen such that the Al(In)GaN exhibits tensile strain that compensates for the compressive strain of InGaN optical confinement wells but does not hinder the optical confinement.
    Type: Grant
    Filed: February 17, 2011
    Date of Patent: January 22, 2013
    Assignee: Corning Incorporated
    Inventors: Rajaram Bhat, Dmitry S. Sizov, Chung-En Zah
  • Patent number: 8355422
    Abstract: A GaN edge emitting laser is provided comprising a semi-polar GaN substrate, an active region, N-side and P-side waveguiding layers, and N-type and P-type cladding layers. The GaN substrate defines a 20 21 crystal growth plane and a glide plane. The N-side and P-side waveguiding layers comprise a GaInN/GaN or GaInN/GaInN superlattice (SL) waveguiding layers. The SL layers of the N-side and P-side SL waveguiding layers have layer thicknesses between approximately 1 nm and 5 nm that are optimized for waveguide planarity. In another embodiments, planarization is enhanced by ensuring that the N-side and P-side GaN-based waveguiding layers are grown at a growth rate that exceeds approximately 0.09 nm/s, regardless of whether the N-side and P-side GaN-based waveguiding layers are provided as a GaInN/GaN SL, GaInN/GaInN SL or as bulk layers. In further embodiments, planarization is enhanced by selecting optimal SL layer thicknesses and growth rates.
    Type: Grant
    Filed: June 11, 2012
    Date of Patent: January 15, 2013
    Assignee: Corning Incorporated
    Inventor: Rajaram Bhat
  • Patent number: 8318515
    Abstract: A method of manufacturing an optoelectronic light emitting semiconductor device is provided where a Multi-quantum Well (MQW) subassembly is subjected to reduced temperature vapor deposition processing to form one or more of n-type or p-type layers over the MQW subassembly utilizing a plurality of precursors and an indium surfactant. The precursors and the indium surfactant are introduced into the vapor deposition process at respective flow rates with the aid of one or more carrier gases, at least one of which comprises H2. The indium surfactant comprises an amount of indium sufficient to improve crystal quality of the p-type layers formed during the reduced temperature vapor deposition processing and the respective precursor flow rates and the H2 content of the carrier gas are selected to maintain a mole fraction of indium from the indium surfactant to be less than approximately 1% in the n-type or p-type layers.
    Type: Grant
    Filed: December 8, 2009
    Date of Patent: November 27, 2012
    Assignee: Corning Incorporated
    Inventor: Rajaram Bhat
  • Publication number: 20120252191
    Abstract: Methods and apparatus for producing a gallium nitride semiconductor on insulator structure include: bonding a single crystal silicon layer to a transparent substrate; and growing a single crystal gallium nitride layer on the single crystal silicon layer.
    Type: Application
    Filed: June 12, 2012
    Publication date: October 4, 2012
    Inventors: Rajaram Bhat, Kishor Purushottam Gadkaree, Jerome Napierala, Linda Ruth Pinckney, Chung-En Zah
  • Publication number: 20120244654
    Abstract: A GaN edge emitting laser is provided comprising a semi-polar GaN substrate, an active region, N-side and P-side waveguiding layers, and N-type and P-type cladding layers. The GaN substrate defines a 20 21 crystal growth plane and a glide plane. The N-side and P-side waveguiding layers comprise a GaInN/GaN or GaInN/GaInN superlattice (SL) waveguiding layers. The SL layers of the N-side and P-side SL waveguiding layers have layer thicknesses between approximately 1 nm and 5 nm that are optimized for waveguide planarity. In another embodiments, planarization is enhanced by ensuring that the N-side and P-side GaN-based waveguiding layers are grown at a growth rate that exceeds approximately 0.09 nm/s, regardless of whether the N-side and P-side GaN-based waveguiding layers are provided as a GaInN/GaN SL, GaInN/GaInN SL or as bulk layers. In further embodiments, planarization is enhanced by selecting optimal SL layer thicknesses and growth rates.
    Type: Application
    Filed: June 11, 2012
    Publication date: September 27, 2012
    Inventor: Rajaram Bhat
  • Publication number: 20120213240
    Abstract: According to the concepts of the present disclosure, laser diode waveguide configurations are contemplated where the use of Al in the waveguide layers of the laser is presented in the form of InGaN/Al(In)GaN waveguiding superstructure comprising optical confining wells (InGaN) and strain compensating barriers (Al(In)GaN). The composition of the optical confining wells is chosen such that they provide strong optical confinement, even in the presence of the Al(In)GaN strain compensating barriers, but do not absorb lasing emission. The composition of the strain compensating barriers is chosen such that the Al(In)GaN exhibits tensile strain that compensates for the compressive strain of InGaN optical confinement wells but does not hinder the optical confinement.
    Type: Application
    Filed: February 17, 2011
    Publication date: August 23, 2012
    Inventors: Rajaram Bhat, Dmitry S. Sizov, Chung-En Zah
  • Patent number: 8217498
    Abstract: Methods and apparatus for producing a gallium nitride semiconductor on insulator structure include: bonding a single crystal silicon layer to a transparent substrate; and growing a single crystal gallium nitride layer on the single crystal silicon layer.
    Type: Grant
    Filed: October 18, 2007
    Date of Patent: July 10, 2012
    Assignee: Corning Incorporated
    Inventors: Rajaram Bhat, Kishor Purushottam Gadkaree, Jerome Napierala, Linda Ruth Pinckney, Chung-En Zah
  • Patent number: 8218595
    Abstract: A GaN edge emitting laser is provided comprising a semi-polar GaN substrate, an active region, an N-side waveguiding layer, a P-side waveguiding layer, an N-type cladding layer, and a P-type cladding layer. The GaN substrate defines a 20 21 crystal growth plane and a glide plane. The N-side and P-side waveguiding layers comprise a GaInN/GaN or GaInN/GaInN superlattice (SL) waveguiding layers. The superlattice layers of the N-side and P-side SL waveguiding layers define respective layer thicknesses that are optimized for waveguide planarity, the layer thicknesses being between approximately 1 nm and approximately 5 nm. In accordance with another embodiment of the present disclosure, planarization can be enhanced by ensuring that the N-side and P-side GaN-based waveguiding layers are grown at a growth rate that exceeds approximately 0.09 nm/s, regardless of whether the N-side and P-side GaN-based waveguiding layers are provided as a GaInN/GaN or GaInN/GaInN SL or as bulk waveguiding layers.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: July 10, 2012
    Assignee: Corning Incorporated
    Inventor: Rajaram Bhat
  • Patent number: 8189639
    Abstract: A GaN-based edge emitting laser is provided comprising a semi-polar GaN substrate, an active region, an N-side waveguiding layer, a P-side waveguiding layer, an N-type cladding layer, and a P-type cladding layer. The GaN substrate is characterized by a threading dislocation density on the order of approximately 1×106/cm2. The strain-thickness product of the N-side waveguiding layer exceeds its strain relaxation critical value. In addition, the cumulative strain-thickness product of the active region calculated for the growth on a the relaxed N-side waveguiding layer is less than its strain relaxation critical value. As a result, the N-side interface between the N-type cladding layer and the N-side waveguiding layer comprises a set of N-side misfit dislocations and the P-side interface between the P-type cladding layer and the P-side waveguiding layer comprises a set of P-side misfit dislocations. Additional embodiments are disclosed and claimed.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: May 29, 2012
    Assignee: Corning Incorporated
    Inventors: Rajaram Bhat, Dmitry Sizov
  • Publication number: 20120069863
    Abstract: Group III nitride-based laser diodes comprise an n-side cladding layer formed of n-doped (Al,In)GaN, an n-side waveguide layer formed of n-doped (Al)InGaN, an active region, a p-side waveguide layer formed of p-doped (Al)InGaN, and a p-side cladding layer formed of p-doped (Al,In)GaN. Optical mode is shifted away from high acceptor concentrations in p-type layers through manipulation of indium concentration and thickness of the n-side waveguide layer. Dopant and compositional profiles of the p-side cladding layer and the p-side waveguide layer are tailored to reduce optical loss and increased wall plug efficiency.
    Type: Application
    Filed: September 20, 2010
    Publication date: March 22, 2012
    Inventors: Dmitry Sizov, Rajaram Bhat, Chung-En Zah
  • Patent number: 8121165
    Abstract: Multi-quantum well laser structures are provided comprising active and/or passive MQW regions. Each of the MQW regions comprises a plurality of quantum wells and intervening barrier layers. Adjacent MQW regions are separated by a spacer layer that is thicker than the intervening barrier layers. The bandgap of the quantum wells is lower than the bandgap of the intervening barrier layers and the spacer layer. The active region may comprise active and passive MQWs and be configured for electrically-pumped stimulated emission of photons or it may comprises active MQW regions configured for optically-pumped stimulated emission of photons.
    Type: Grant
    Filed: June 16, 2011
    Date of Patent: February 21, 2012
    Assignee: Corning Incorporated
    Inventors: Rajaram Bhat, Jerome Napierala, Dmitry Sizov, Chung-En Zah
  • Publication number: 20110292958
    Abstract: A GaN edge emitting laser is provided comprising a semi-polar GaN substrate, an active region, an N-side waveguiding layer, a P-side waveguiding layer, an N-type cladding layer, and a P-type cladding layer. The GaN substrate defines a 20 21 crystal growth plane and a glide plane. The N-side and P-side waveguiding layers comprise a GaInN/GaN or GaInN/GaInN superlattice (SL) waveguiding layers. The superlattice layers of the N-side and P-side SL waveguiding layers define respective layer thicknesses that are optimized for waveguide planarity, the layer thicknesses being between approximately 1 nm and approximately 5 nm. In accordance with another embodiment of the present disclosure, planarization can be enhanced by ensuring that the N-side and P-side GaN-based waveguiding layers are grown at a growth rate that exceeds approximately 0.09 nm/s, regardless of whether the N-side and P-side GaN-based waveguiding layers are provided as a GaInN/GaN or GaInN/GaInN SL or as bulk waveguiding layers.
    Type: Application
    Filed: May 28, 2010
    Publication date: December 1, 2011
    Inventor: Rajaram Bhat
  • Publication number: 20110292957
    Abstract: A GaN-based edge emitting laser is provided comprising a semi-polar GaN substrate, an active region, an N-side waveguiding layer, a P-side waveguiding layer, an N-type cladding layer, and a P-type cladding layer. The GaN substrate is characterized by a threading dislocation density on the order of approximately 1×106/cm2. The strain-thickness product of the N-side waveguiding layer exceeds its strain relaxation critical value. In addition, the cumulative strain-thickness product of the active region calculated for the growth on a the relaxed N-side waveguiding layer is less than its strain relaxation critical value. As a result, the N-side interface between the N-type cladding layer and the N-side waveguiding layer comprises a set of N-side misfit dislocations and the P-side interface between the P-type cladding layer and the P-side waveguiding layer comprises a set of P-side misfit dislocations. Additional embodiments are disclosed and claimed.
    Type: Application
    Filed: May 28, 2010
    Publication date: December 1, 2011
    Inventors: Rajaram Bhat, Dmitry Sizov
  • Publication number: 20110243173
    Abstract: Multi-quantum well laser structures are provided comprising active and/or passive MQW regions. Each of the MQW regions comprises a plurality of quantum wells and intervening barrier layers. Adjacent MQW regions are separated by a spacer layer that is thicker than the intervening barrier layers. The bandgap of the quantum wells is lower than the bandgap of the intervening barrier layers and the spacer layer. The active region may comprise active and passive MQWs and be configured for electrically-pumped stimulated emission of photons or it may comprises active MQW regions configured for optically-pumped stimulated emission of photons.
    Type: Application
    Filed: June 16, 2011
    Publication date: October 6, 2011
    Inventors: Rajaram Bhat, Jerome Napierala, Dmitry Sizov, Chung-En Zah
  • Patent number: 7983317
    Abstract: Multi-quantum well laser structures are provided comprising active and/or passive MQW regions. Each of the MQW regions comprises a plurality of quantum wells and intervening barrier layers. Adjacent MQW regions are separated by a spacer layer that is thicker than the intervening barrier layers. The bandgap of the quantum wells is lower than the bandgap of the intervening barrier layers and the spacer layer. The active region may comprise active and passive MQWs and be configured for electrically-pumped stimulated emission of photons or it may comprises active MQW regions configured for optically-pumped stimulated emission of photons.
    Type: Grant
    Filed: December 16, 2008
    Date of Patent: July 19, 2011
    Assignee: Corning Incorporated
    Inventors: Rajaram Bhat, Jerome Napierala, Dmitry Sizov, Chung-En Zah