Radio-frequency carbon-nanotube field effect transistor devices with local backgates and methods for making same
A radio-frequency (RF) carbon-nanotube (CNT) field effect transistor (FET) device. The device includes a source contact, a drain contact, semi-conducting CNTs positioned between the source and drain contacts, high-κ gate dielectric, and a local backgate positioned below the semi-conducting CNTs, in which the local backgate is capable of RF performance and is capable of being used in a backgate burnout process used to enhance the semiconducting to metallic tube ratio of the device.
1. A method for making a radio-frequency (RF) carbon-nanotube (CNT) field effect transistor (FET) device comprising:
depositing a local backgate structure on a RF compatible substrate, wherein depositing the local backgate structure includes:
depositing a thin titanium layer;
depositing a platinum layer on top of the titanium layer;
depositing a gold layer on top of the platinum layer; and
depositing chrome on top of the gold layer;
depositing high-κ gate dielectric layer on top of the local backgate structure;
depositing CNTs on the high-κ gate dielectric layer, wherein the CNTs include metallic and semi-conducting CNTs;
depositing source and drain contacts adjacent to CNTs;
applying a voltage to the local backgate sufficient to deplete the semi-conducting CNTs; and
applying a voltage to the source and drain contacts sufficient to burn-out the metallic CNTs, wherein the metallic CNTs are removed.
2. A method for making a radio-frequency (RF) carbon-nanotube (CNT) field effect transistor (FET) device comprising:
depositing a local backgate structure on a RF compatible substrate, wherein depositing the local backgate structure includes patterning and depositing multiple gate stacks on substrate;
depositing high-κ gate dielectric layer on top of the local backgate structure;
depositing CNTs on the high-κ gate dielectric layer, wherein the CNTs include metallic and semi-conducting CNTs;
depositing source and drain contacts adjacent to CNTs;
applying a voltage to the local backgate sufficient to deplete the semi-conducting CNTs; and
applying a voltage to the source and drain contacts sufficient to burn-out the metallic CNTs, wherein the metallic CNTs are removed.
3. A method for making a radio-frequency (RF) carbon-nanotube (CNT) field effect transistor (FET) device comprising:
depositing a local backgate structure on a RF compatible substrate;
depositing high-κ gate dielectric layer on top of the local backgate structure;
depositing CNTs on the high-κ gate dielectric layer, wherein the CNTs include metallic and semi-conducting CNTs;
depositing source and drain contacts adjacent to CNTs;
applying a photomask to CNTs prior to depositing source and drain contacts;
applying a voltage to the local backgate sufficient to deplete the semi-conducting CNTs; and
applying a voltage to the source and drain contacts sufficient to burn-out the metallic CNTs, wherein the metallic CNTs are removed.
4. A method for making a radio-frequency (RF) carbon-nanotube (CNT) field effect transistor (FET) device comprising:
depositing a local backgate structure on a RF compatible substrate, wherein the RF compatible substrate is an amorphous quartz wafer, a high resistivity silicon wafer, a silicon carbide wafer, or a sapphire wafer;
depositing high-κ gate dielectric layer on top of the local backgate structure;
depositing CNTs on the high-κ gate dielectric layer, wherein the CNTs include metallic and semi-conducting CNTs;
depositing source and drain contacts adjacent to CNTs;
applying a voltage to the local backgate sufficient to deplete the semi-conducting CNTs; and
applying a voltage to the source and drain contacts sufficient to burn-out the metallic CNTs, wherein the metallic CNTs are removed.