A Low-cost Planar Inkjet-printed Carbon Nanotube Field Effect Transistor for Sensor and Circuit Applications
[Thesis]
Islam, Md Toriqul
Haider, Mohammad Rafiqul
The University of Alabama at Birmingham
2019
114 p.
M.S.
The University of Alabama at Birmingham
2019
The semiconductor-based transistor is an essential building block of electronic components, computing applications, and sensors. However, the fabrication of this primary electronic element is complex and costly, especially when considering flexible electronics for bio-sensing applications. This thesis work proposes a new circuit manufacturing technique to print planar inkjet-printed carbon nanotube field effect transistor (CNTFET), sensor and circuits on paper and polyethylene terephthalate (PET) film substrate to reduce the complexity of the system and to lower the cost of conventional fabrication schemes. Single walled carbon nanotubes (SWCNTs) are being used as semiconductor ink for an inkjet-printer to facilitate and fabricate two types of transistors. Both thin (0.3 mm gate separation) and thick (0.5 mm gate separation) transistors with wide (4 mm) and narrow (2 mm) channel length have shown nearly linear characteristics of resistivity for a range of applied gate voltages. Though the experimental results are not similar compared to a real transistor, the mathematical model shows excellent usage of the proposed inkjet-printed CNTFET for various electronic applications including but not limited to biosensors, healthcare measurements, and circuits. CNTFET model was used in PSpice circuit to check its usability in practical applications. Also, printed sensor circuits were studied for the validity of the inkjet printing technologies being used in flexible electronics fabrication. Experimental results show that environmental factors play a significant role in the performance of the printed transistors and circuits.