A “Bottom-Up” Redefinition for Mobility and the Effect of Poor Tube–Tube Contact on the Performance of CNT Nanonet Thin-Film Transistors

Nanonet thin-film transistors (NN-TFTs) based on random or aligned networks of single-wall carbon nanotubes are often regarded as a promising high-performance alternative to amorphous-Si technology for various macroelectronics applications involving sensors and displays. The comparison of NN-TFTs with other competing technologies such as organic, a-Si, and p-Si TFTs, however, has proved difficult as the mobility of these devices (counterintuitively) depends on a host of geometrical parameters such as tube density
D
, tube length
LS
, channel length
LC
, tube-tube contact
C

_ij
, etc. In this letter, we redefine the mobility for NN-TFTs by generalizing the classical definition from a ldquobottom-uprdquo perspective based on a stick percolation model. This new definition would allow a direct comparison of NN-TFT mobilities across different laboratories and with other competing technologies. We also suggest a simple experimental measure of the critical tube-tube contact
C

_ij
parameter to allow design of optimized transistors.