Current crowding in two-dimensional black-phosphorus field-effect transistors

By combining electrical measurements, scanning Kelvin probe microscopy, and numerical electrical simulations, we find significant current crowding in two-dimensional (2D) black phosphorus field-effect transistors. This current crowding can lead to localized Joule heating close to the metal contacts, and it is consistent with the features of the device failure observed in this study. Importantly, by considering both Schottky and resistive Ohmic contact models, we find that the commonly used transmission-line model, in general, significantly underestimates the extent of the current crowding. These findings, which are likely to be relevant in other 2D materials, suggest the need to take into account the current crowding effect in designing 2D devices. (C) 2016 AIP Publishing LLC.