High frequency Scanning Gate Microscopy and local memory effect of carbon nanotube transistors

TL;DR

This study extends high frequency impedance spectroscopy and scanning gate microscopy to analyze single-walled carbon nanotube transistors, revealing their RC circuit behavior and local memory effects at nanometer scales.

Contribution

It introduces high frequency SGM imaging up to 15MHz and demonstrates the local memory effect in swCN-FETs, enabling potential miniaturization of nanotube-based memory.

Findings

swCN-FETs behave as simple RC circuits with a 0.3 ms time constant

SGM at 15MHz can image impedance changes in real-time

Memory effects are localized, allowing for nanoscale memory cells

Abstract

We use impedance spectroscopy to measure the high frequency properties of single-walled carbon nanotube field effect transistors (swCN-FETs). Furthermore, we extend Scanning Gate Microscopy (SGM) to frequencies up to 15MHz, and use it to image changes in the impedance of swCN-FET circuits induced by the SGM-tip gate. In contrast to earlier reports, the results of both experiments are consistent with a simple RC parallel circuit model of the swCN-FET, with a time constant of 0.3 ms. We also use the SGM tip to show the local nature of the memory effect normally observed in swCN-FETs, implying that nanotube-based memory cells can be miniaturized to dimensions of the order of tens of nm.