Electrical contact properties between carbon nanotube ends and a conductive atomic force microscope tip

Abstract

Understanding the electrical contact properties of carbon nanotube (CNT) ends is important to use the high conductance of CNTs in the CNT on-axis direction in applications such as through-silicon via structures. In this study, we experimentally evaluated the contact resistivity between single-/multi-walled CNT ends and a metal nanoprobe using conductive atomic force microscopy (C-AFM). To validate the measured end contact resistivity, we compared our experimentally determined value with that obtained from numerical calculations and reported values for side contact resistivity. The contact resistivity normalized by the length of the CNT ends was 0.6–2.4 × 106 Ω nm for single-walled CNTs. This range is 1–2 orders of magnitude higher than that determined theoretically. The contact resistivity of a single-walled CNT end with metal normalized by the contact area was 2–3 orders of magnitude lower than that reported for the resistivity of a CNT sidewall/metal contact. For multi-walled CNTs, the measured contact resistivity was one order of magnitude higher than that of a CNT forest grown by remote plasma-enhanced chemical vapor deposition, whereas the contact resistivity of a top metal electrode was similar to that obtained for a single-walled CNT forest.