Patents by Inventor Valeri F. Tsvetkov

Valeri F. Tsvetkov 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).

  • Semi-insulating silicon carbide without vanadium domination
    Patent number: 6639247
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Grant
    Filed: March 16, 2001
    Date of Patent: October 28, 2003
    Assignee: Cree, Inc.
    Inventors: Calvin H. Carter, Jr., Mark Brady, Valeri F. Tsvetkov
  • Semi-insulating silicon carbide without vanadium domination
    Patent number: 6403982
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Grant
    Filed: January 10, 2001
    Date of Patent: June 11, 2002
    Assignee: Cree, Inc.
    Inventors: Calvin H. Carter, Jr., Mark Brady, Valeri F. Tsvetkov
  • Semi-insulating silicon carbide without vanadium domination
    Patent number: 6396080
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of trapping elements that create states at least 700 meV from the valence or conduction band that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Grant
    Filed: May 25, 2001
    Date of Patent: May 28, 2002
    Assignee: Cree, Inc
    Inventors: Calvin H. Carter, Jr., Mark Brady, Valeri F. Tsvetkov
  • Semi-insulating silicon carbide without vanadium domination
    Publication number: 20010023945
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of trapping elements that create states at least 700 meV from the valence or conduction band that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Application
    Filed: May 25, 2001
    Publication date: September 27, 2001
    Inventors: Calvin H. Carter, Mark Brady, Valeri F. Tsvetkov
  • Semi-insulating silicon carbide without vanadium domination
    Publication number: 20010019132
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Application
    Filed: January 10, 2001
    Publication date: September 6, 2001
    Inventors: Calvin H. Carter, Mark Brady, Valeri F. Tsvetkov
  • Semi-insulating silicon carbide without vanadium domination
    Publication number: 20010017374
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Application
    Filed: March 16, 2001
    Publication date: August 30, 2001
    Inventors: Calvin H. Carter, Mark Brady, Valeri F. Tsvetkov
  • Semi-insulating silicon carbide without vanadium domination
    Patent number: 6218680
    Abstract: A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 &OHgr;-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.
    Type: Grant
    Filed: May 18, 1999
    Date of Patent: April 17, 2001
    Assignee: Cree, Inc.
    Inventors: Calvin H. Carter, Jr., Mark Brady, Valeri F. Tsvetkov
  • Colorless silicon carbide gemstones
    Patent number: 6200917
    Abstract: Large single crystals of silicon carbide are grown in a furnace sublimation system. The crystals are grown with compensating levels of p-type and n-type dopants (i.e., roughly equal levels of the two dopants) in order to produce a crystal that is essentially colorless. The crystal may be cut and fashioned into synthetic gemstones having extraordinary toughness and hardness, and a brilliance meeting or exceeding that of diamond.
    Type: Grant
    Filed: February 14, 2000
    Date of Patent: March 13, 2001
    Assignee: Cree, Inc.
    Inventors: Calvin H. Carter, Valeri F. Tsvetkov, Robert C. Glass
  • Colorless silicon carbide crystals
    Patent number: 6025289
    Abstract: Large single crystals of silicon carbide are grown in a furnace sublimation system. The crystals are grown with compensating levels of p-type and n-type dopants (i.e., roughly equal levels of the two dopants) in order to produce a crystal that is essentially colorless. The crystal may be cut and fashioned into synthetic gemstones having extraordinary toughness and hardness, and a brilliance meeting or exceeding that of diamond.
    Type: Grant
    Filed: December 4, 1997
    Date of Patent: February 15, 2000
    Assignee: Cree Research, Inc.
    Inventors: Calvin H. Carter, Valeri F. Tsvetkov, Robert C. Glass
  • Growth of colorless silicon carbide crystals
    Patent number: 5718760
    Abstract: Large single crystals of silicon carbide are grown in a furnace sublimation system. The crystals are grown with compensating levels of p-type and n-type dopants (i.e., roughly equal to levels of the two dopants) in order to produce a crystal that is essentially colorless. The crystal may be cut and fashioned into synthetic gemstones having extraordinary toughness and hardness, and a brilliance meeting or exceeding that of diamond.
    Type: Grant
    Filed: February 5, 1996
    Date of Patent: February 17, 1998
    Assignee: Cree Research, Inc.
    Inventors: Calvin H. Carter, Valeri F. Tsvetkov, Robert C. Glass