Patents by Inventor George Stojan Tulevski
George Stojan Tulevski 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).
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Patent number: 9273004Abstract: A method of forming a structure having selectively placed carbon nanotubes, a method of making charged carbon nanotubes, a bi-functional precursor, and a structure having a high density carbon nanotube layer with minimal bundling. Carbon nanotubes are selectively placed on a substrate having two regions. The first region has an isoelectric point exceeding the second region's isoelectric point. The substrate is immersed in a solution of a bi-functional precursor having anchoring and charged ends. The anchoring end bonds to the first region to form a self-assembled monolayer having a charged end. The substrate with charged monolayer is immersed in a solution of carbon nanotubes having an opposite charge to form a carbon nanotube layer on the self-assembled monolayer. The charged carbon nanotubes are made by functionalization or coating with an ionic surfactant.Type: GrantFiled: September 29, 2011Date of Patent: March 1, 2016Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Hongsik Park, George Stojan Tulevski
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Patent number: 9105853Abstract: A composition and method for forming a field effect transistor with a stable n-doped nano-component. The method includes forming a gate dielectric on a gate, forming a channel comprising a nano-component on the gate dielectric, forming a source over a first region of the nano-component, forming a drain over a second region of the nano-component to form a field effect transistor, and exposing a portion of a nano-component of a field effect transistor to dihydrotetraazapentacene, wherein dihydrotetraazapentacene is represented by the formula: wherein each of R1, R2, R3, and R4 comprises one of hydrogen, an alkyl group of C1 to C16 carbons, an alkoxy group, an alkylthio group, a trialkylsilane group, a hydroxymethyl group, a carboxylic acid group and a carboxylic ester group.Type: GrantFiled: October 11, 2013Date of Patent: August 11, 2015Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Bhupesh Chandra, George Stojan Tulevski
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Patent number: 8895417Abstract: A method and an apparatus for doping at least one of a graphene and a nanotube thin-film transistor field-effect transistor device to decrease contact resistance with a metal electrode. The method includes selectively applying a dopant to a metal contact region of at least one of a graphene and a nanotube field-effect transistor device to decrease the contact resistance of the field-effect transistor device.Type: GrantFiled: November 29, 2011Date of Patent: November 25, 2014Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Bhupesh Chandra, George Stojan Tulevski, Fengnian Xia
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Patent number: 8853034Abstract: Techniques for increasing conductivity of graphene films by chemical doping are provided. In one aspect, a method for increasing conductivity of a graphene film includes the following steps. The graphene film is formed from one or more graphene sheets. The graphene sheets are exposed to a solution having a one-electron oxidant configured to dope the graphene sheets to increase a conductivity thereof, thereby increasing the overall conductivity of the film. The graphene film can be formed prior to the graphene sheets being exposed to the one-electron oxidant solution. Alternatively, the graphene sheets can be exposed to the one-electron oxidant solution prior to the graphene film being formed. A method of fabricating a transparent electrode on a photovoltaic device from a graphene film is also provided.Type: GrantFiled: September 14, 2012Date of Patent: October 7, 2014Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Ageeth Anke Bol, George Stojan Tulevski
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Patent number: 8785911Abstract: Transistor devices having nanoscale material-based channels (e.g., carbon nanotube or graphene channels) and techniques for the fabrication thereof are provided. In one aspect, a transistor device is provided. The transistor device includes a substrate; an insulator on the substrate; a local bottom gate embedded in the insulator, wherein a top surface of the gate is substantially coplanar with a surface of the insulator; a local gate dielectric on the bottom gate; a carbon-based nanostructure material over at least a portion of the local gate dielectric, wherein a portion of the carbon-based nanostructure material serves as a channel of the device; and conductive source and drain contacts to one or more portions of the carbon-based nanostructure material on opposing sides of the channel that serve as source and drain regions of the device.Type: GrantFiled: June 23, 2011Date of Patent: July 22, 2014Assignee: International Business Machines CorporationInventors: Zhihong Chen, Aaron Daniel Franklin, Shu-Jen Han, James Bowler Hannon, Katherine L. Saenger, George Stojan Tulevski
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Patent number: 8772910Abstract: A method and an apparatus for doping a graphene or nanotube thin-film field-effect transistor device to improve electronic mobility. The method includes selectively applying a dopant to a channel region of a graphene or nanotube thin-film field-effect transistor device to improve electronic mobility of the field-effect transistor device.Type: GrantFiled: November 29, 2011Date of Patent: July 8, 2014Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Bhupesh Chandra, George Stojan Tulevski
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Patent number: 8772141Abstract: A method for doping a graphene or nanotube thin-film field-effect transistor device to improve electronic mobility. The method includes selectively applying a dopant to a channel region of a graphene or nanotube thin-film field-effect transistor device to improve electronic mobility of the field-effect transistor device.Type: GrantFiled: September 26, 2012Date of Patent: July 8, 2014Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Bhupesh Chandra, George Stojan Tulevski
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Publication number: 20140038350Abstract: A composition and method for forming a field effect transistor with a stable n-doped nano-component. The method includes forming a gate dielectric on a gate, forming a channel comprising a nano-component on the gate dielectric, forming a source over a first region of the nano-component, forming a drain over a second region of the nano-component to form a field effect transistor, and exposing a portion of a nano-component of a field effect transistor to dihydrotetraazapentacene, wherein dihydrotetraazapentacene is represented by the formula: wherein each of R1, R2, R3, and R4 comprises one of hydrogen, an alkyl group of C1 to C16 carbons, an alkoxy group, an alkylthio group, a trialkylsilane group, a hydroxymethyl group, a carboxylic acid group and a carboxylic ester group.Type: ApplicationFiled: October 11, 2013Publication date: February 6, 2014Applicant: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Bhupesh Chandra, George Stojan Tulevski
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Patent number: 8642432Abstract: A composition and method for forming a field effect transistor with a stable n-doped nano-component. The method includes forming a gate dielectric on a gate, forming a channel comprising a nano-component on the gate dielectric, forming a source over a first region of the nano-component, forming a drain over a second region of the nano-component to form a field effect transistor, and exposing a portion of a nano-component of a field effect transistor to dihydrotetraazapentacene to produce a stable n-doped nano-component, wherein dihydrotetraazapentacene is represented by the formula: wherein in the dihydrotetraazapentacene chemical structure, each of R1, R2, R3, and R4 can be hydrogen, an alkyl group of C1 to C16 carbons, an alkoxy group, an alkylthio group, a trialkylsilane group, a hydroxymethyl group, a carboxylic acid group or a carboxylic ester group.Type: GrantFiled: December 1, 2011Date of Patent: February 4, 2014Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Bhupesh Chandra, George Stojan Tulevski
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Publication number: 20130082233Abstract: A method of forming a structure having selectively placed carbon nanotubes, a method of making charged carbon nanotubes, a bi-functional precursor, and a structure having a high density carbon nanotube layer with minimal bundling. Carbon nanotubes are selectively placed on a substrate having two regions. The first region has an isoelectric point exceeding the second region's isoelectric point. The substrate is immersed in a solution of a bi-functional precursor having anchoring and charged ends. The anchoring end bonds to the first region to form a self-assembled monolayer having a charged end. The substrate with charged monolayer is immersed in a solution of carbon nanotubes having an opposite charge to form a carbon nanotube layer on the self-assembled monolayer. The charged carbon nanotubes are made by functionalization or coating with an ionic surfactant.Type: ApplicationFiled: September 29, 2011Publication date: April 4, 2013Applicant: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Hongsik Park, George Stojan Tulevski
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Publication number: 20130025662Abstract: Techniques for reducing the resistivity of carbon nanotube and graphene materials are provided. In one aspect, a method of producing a doped carbon film having reduced resistivity is provided. The method includes the following steps. A carbon material selected from the group consisting of: a nanotube, graphene, fullerene and pentacene is provided. The carbon material and a dopant solution comprising an oxidized form of ruthenium bipyridyl are contacted, wherein the contacting is carried out under conditions sufficient to produce the doped carbon film having reduced resistivity.Type: ApplicationFiled: July 25, 2011Publication date: January 31, 2013Applicant: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Ageeth Anke Bol, Bhupesh Chandra, George Stojan Tulevski
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Publication number: 20130011960Abstract: Techniques for increasing conductivity of graphene films by chemical doping are provided. In one aspect, a method for increasing conductivity of a graphene film includes the following steps. The graphene film is formed from one or more graphene sheets. The graphene sheets are exposed to a solution having a one-electron oxidant configured to dope the graphene sheets to increase a conductivity thereof, thereby increasing the overall conductivity of the film. The graphene film can be formed prior to the graphene sheets being exposed to the one-electron oxidant solution. Alternatively, the graphene sheets can be exposed to the one-electron oxidant solution prior to the graphene film being formed. A method of fabricating a transparent electrode on a photovoltaic device from a graphene film is also provided.Type: ApplicationFiled: September 14, 2012Publication date: January 10, 2013Applicant: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Ageeth Anke Bol, George Stojan Tulevski
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Publication number: 20120326126Abstract: Transistor devices having nanoscale material-based channels (e.g., carbon nanotube or graphene channels) and techniques for the fabrication thereof are provided. In one aspect, a transistor device is provided. The transistor device includes a substrate; an insulator on the substrate; a local bottom gate embedded in the insulator, wherein a top surface of the gate is substantially coplanar with a surface of the insulator; a local gate dielectric on the bottom gate; a carbon-based nanostructure material over at least a portion of the local gate dielectric, wherein a portion of the carbon-based nanostructure material serves as a channel of the device; and conductive source and drain contacts to one or more portions of the carbon-based nanostructure material on opposing sides of the channel that serve as source and drain regions of the device.Type: ApplicationFiled: June 23, 2011Publication date: December 27, 2012Applicant: International Business Machines CorporationInventors: Zhihong Chen, Aaron Daniel Franklin, Shu-Jen Han, James Bowler Hannon, Katherine L. Saenger, George Stojan Tulevski
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Patent number: 8293607Abstract: Techniques for increasing conductivity of graphene films by chemical doping are provided. In one aspect, a method for increasing conductivity of a graphene film includes the following steps. The graphene film is formed from one or more graphene sheets. The graphene sheets are exposed to a solution having a one-electron oxidant configured to dope the graphene sheets to increase a conductivity thereof, thereby increasing the overall conductivity of the film. The graphene film can be formed prior to the graphene sheets being exposed to the one-electron oxidant solution. Alternatively, the graphene sheets can be exposed to the one-electron oxidant solution prior to the graphene film being formed. A method of fabricating a transparent electrode on a photovoltaic device from a graphene film is also provided.Type: GrantFiled: August 19, 2010Date of Patent: October 23, 2012Assignee: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Ageeth Anke Bol, George Stojan Tulevski
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Publication number: 20120045865Abstract: Techniques for increasing conductivity of graphene films by chemical doping are provided. In one aspect, a method for increasing conductivity of a graphene film includes the following steps. The graphene film is formed from one or more graphene sheets. The graphene sheets are exposed to a solution having a one-electron oxidant configured to dope the graphene sheets to increase a conductivity thereof, thereby increasing the overall conductivity of the film. The graphene film can be formed prior to the graphene sheets being exposed to the one-electron oxidant solution. Alternatively, the graphene sheets can be exposed to the one-electron oxidant solution prior to the graphene film being formed. A method of fabricating a transparent electrode on a photovoltaic device from a graphene film is also provided.Type: ApplicationFiled: August 19, 2010Publication date: February 23, 2012Applicant: International Business Machines CorporationInventors: Ali Afzali-Ardakani, Ageeth Anke Bol, George Stojan Tulevski