Impact of Morphology on Printed Contact Performance in Carbon Nanotube Thin‐Film Transistors

Abstract

Silver nanoparticles (NPs) are the most widely used conductive material throughout the printed electronics space due to their high conductivity and low cost. However, when interfacing with other prominent printed materials, such as semiconducting carbon nanotubes (CNTs) in thin-film transistors (TFTs), silver is suboptimal when compared to more expensive or less conductive materials. Consequently, there would be significant value to improving the interface of printed silver to CNT films. In this work, the impact of nanostructure morphology on the electrical properties of printed silver and nanotube junctions in CNT-TFTs is investigated. Three distinct silver morphologies (NPs, nanoflakes -NFs, and nanowires -NWs) are explored with top-and bottom-contact configurations for each. The NF morphology in a top-contact configuration is found to yield the best electrical interface to CNTs, resulting in an average contact resistance of 1.2 MΩ ⋅ µm. Beyond electrical performance, several trade-offs in morphology selection are revealed, including print resolution and process temperature. While NF inks produce the best interfaces, NP inks produce the smallest features, and NW inks are compatible with low processing temperatures (<80 °C). These results outline the trade-offs between silver contact morphologies in CNT-TFTs and show that contact morphology selection can be tailored for specific applications.

Retracted: Combined Printing of Highly Aligned Single‐Walled Carbon Nanotube Thin Films with Liquid Metal for Direct Fabrication of Functional Electronic Devices

“…We next examine the principal performance parameters of flexible CNT TFTs in the context of previously reported CNT TFT design trade-off relation-ships. [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] Figure 7a-c shows on/off ratios plotted as a function of normalized g m , V th , and parallel-plate field-effect mobility (µ), respectively. It can be clearly seen that the performance of our LM-CNT device exhibit R e t r a c t e d significantly higher transconductance and low-voltage operation while maintaining a large on/off ratio of >10 5 due to the combined high-conductance and flexibility.…”

Silver Nanoparticles Based Ink with Moderate Sintering in Flexible and Printed Electronics

“…The requirement of printed Ag NPs based electrodes is not only low resistance but also good contact with semiconductor and good morphology. Printed Ag NPs based source/drain electrodes have been commonly reported in p-type organic and carbon-nanotube TFT [118,119,120,121,122,123], though the intrinsic work function of Ag is as low as 4.26 eV [124]. It may be due to the formation of Ag 2 O on a surface that is a high-doped degenerate p-type semiconductor with high work function and moderate electric conductivity.…”

“…Metallic Ag NPs undergo undesirable electrical/thermal migration [115,132], which would result in unpredictable degradation of the device performance [115,122]. Hong et al reported high-performance oxide thin-film transistors, by surrounding Ag nanoparticles firmly with oleic acid to suppress the migration of Ag inside adjacent oxide semiconductors.…”

Recent Progress in Photonic Synapses for Neuromorphic Systems

“…Carbon nanotubes have been considered as one of the emerging 1D materials that present high charge carrier mobility, excellent physical and chemical stability, and proper operating temperature . In addition to combining with semiconductors, carbon nanotubes assisted in lightly n‐doped Si transistor can also realize the emulation of synaptic behaviors.…”