Field Effect Transistors using Carbon Nanotubes |
Slide 2 |
How a NTFET Works |
How a NTFET Works |
How a NTFET Works |
Nanotube FET transistor |
Effect of charge transfer on the device electronics |
Slide 8 |
Metallic vs. Semiconducting |
Metallic Tubes are the Enemy |
Deposition Techniques |
Want: Uniform Film of individually separated NT’s | |||
Direct Deposition | |||
Drop Casting -- Flocculation due to Van der Waals | |||
between tubes limits uniformity. | |||
Spin Coating – work in progress | |||
Langmuir-Blodgett/Quasi-Langmuir-Blodgett | |||
Separate Tubes using Solubilization Agents | |||
Starch/Enzymes | |||
PmPV | |||
Quasi-Langmuir-Blodgett Film |
Quasi-Langmuir-Blodgett Film |
Quasi-Langmuir-Blodgett Film |
Quasi-Langmuir-Blodgett Film |
Why 10:1 solvent mixture? |
Ortho-xylene:Dichlorobenzene solvent mixture used for 3 reasons | ||
1) High nanotube solubility ≈ 15 mg/L | ||
2) Specific Gravity < 1 (so rafts can float) | ||
3) Immiscibile in water |
Quasi-Langmuir-Blodgett Film |
Does water Immersion affect Films? |
Quasi-LB Film: Are They Uniform? |
Device Fabrication |
Measurement Setup |
Output (Vg ) ±100 V quasi-AC | |
Sawtooth Waveform. | |
Output bias voltage (100mV) | |
across SD, and measure Isd | |
Measure Voltage across Rprot to get Ileakage | |
Transistor Characteristics |
Transistor Characteristics |
Transistor Characteristics |
Vsd vs Isd |
Transistor Characteristics |
Exponentially Better with Film thinness |
Calculation of Mobility |
Quadratic Model of MOSFET: | |||
ISD = (μCoxW)[(VGS – VT)VDS – VDS2/2] for VDS << VGS – VT | |||
Slope of IVg curve = μCoxWVDS | |||
Plugging in the numbers yields mobility of 0.9 cm2/V*s | |||
Mobility's: Single Carbon NT = 105 | |||
Silicon = 102-103 | |||
NT Network = 101 | |||
Organic Semiconductor = 10-4 - 10-1 | |||
High Mobility means device can operate at Higher frequency!!! | |||
Liquid Gating |
Nanotube Reflux in Nitric Acid |
Slide 31 |
Did the Reflux Work? |
Future Work |
Improve Device Characteristics | ||
Thinner Films | ||
More Dispersed Tubes | ||
Separate Semiconducting and Metallic Tubes | ||
Mobility vs. applied pressure | ||
Improve Probe Station | ||
True AC Setup | ||
Gold Pogo Pin probe/Micrometer positioner | ||
Temperature/Humidity Control Chamber | ||
Characteristics vs. Network Density | ||
Photo-lithographic Mask for micro scale geometries | ||
Study 2-D Percolation problem of random array of semiconducting rods | ||
E-Beam Lithography for nano scale geometries | ||
Protein detection | ||
Conclusion |
Created NT network transistor using room temperature fabrication process | |
Film too thick to get good characteristics. |
Thanks |
The Gruner Group: Peter Armitage, M. Briman, Erika Artukovic, Liangbing Hu, George Gruner | |
The Chemists: Erik Richman, Will Molenkamp (Tolbert); Matt Spotnitz (Kaner). | |
Steve Franz (Nanolab). | |
MCTP |