Polymer coating boosts carbon nanotube transistor performance
1 min read
The reliability and performance of transistors and circuits based on single walled carbon nanotubes can be improved by coating them with a fluoropolymer.
According to researchers from the University of Texas at Austin and Northwestern University, although circuits made with single walled carbon nanotubes are expected to be more energy efficient than those made from silicon, their drawbacks, such as high power dissipation and less stability, currently limit their application.
To overcome these drawbacks, the researchers inkjet printed PVDF-TrFE on the top of self fabricated single walled carbon nanotube transistors. The fluoropolymer coated film was then annealed in air at 140°C for three minutes.
"We attribute the improvements to the polar nature of PVDF-TrFE that mitigates the negative effect of impurities and defects on the performance of semiconductor single walled carbon nanotubes," said Professor Ananth Dodabalapur from UT Austin.
On the device level, significant improvements were seen in parameters such as off current magnitude, degree of hysteresis, variation in threshold voltage and bias stress degradation. According to Prof Dodabalapur, this means more energy efficient, stable and uniform transistors with longer life times. On the circuit level, improved uniformity in device characteristics improved the performance of a five stage complementary ring oscillator circuit.
"The oscillation frequency and amplitude of the single walled carbon nanotube ring oscillator circuit increased by 42% and 250% respectively," said Prof Dodabalapur. The parameters indicate a faster and better performing circuit with possibly reduced power consumption.
The researchers now plan to apply their findings to more complex circuits.
