Dielectric breakdown of 2D muscovite mica

Localized electrical breakdown (BD) measurements are performed on 2D muscovite mica flakes of ~ 2 to 15 nm thickness using Conduction Atomic Force Microscopy (CAFM). To obtain robust BD data by CAFM, the probed locations are spaced sufficiently far apart (> 1 µm) to avoid mutual interference and the maximum current is set to a low value (< 1 nA) to ensure severe damage does not occur to the sample. The analyses reveals that 2D muscovite mica has high electrical breakdown strength (12 MV/cm or more) and low leakage current, comparable to 2D hexagonal boron nitride (h-BN) of similar thickness. However, a significant difference compared to h-BN is the very low current necessary to avoid catastrophic damage during the BD event, even for very thin (2–3 nm) flakes. Further, for mica the BD transient always appear to be very abrupt, and no progressive BD process was definitively observed. These marked differences between mica and h-BN are attributed to the poor thermal conductivity of mica.