Impact of External Perturbations on Carbon Nanotube Electronic Structure*

While single-walled carbon nanotubes (SWCNTs) can exhibit ballistic charge transport, their electronic behavior is highly sensitive to environmental effects. Environmental inhomgeneities, such as defects in the gate dielectric of a SWCNT transistor, can perturb the local electronic structure of the SWCNT, leading to localized states. These localized states may trap charge carriers, significantly degrading device performance. In this work, we use scanning tunneling microscopy and spectroscopy to investigate the impact of inhomegeneities in a dielectric on the local density of states (LDOS) of SWCNTs. We use a monolayer of RbI on Au(111) as our model dielectric, and find that anti-phase defects in the RbI lead to perturbations in the RbI LDOS, which generate spatially-confined mid-gap states in the SWCNT. We will also discuss recent density functional theory results examining the impact of external charges on SWCNT LDOS.