Abstract
The electronic properties of black and blue phosphorus nanoribbons are investigated, which enables the proposal of junction-free field-effect transistors that comprise metallic armchair nanoribbons as electrodes and, in between, a semiconducting zigzag nanoribbon as channel material (cut out of a single sheet of monolayer black or blue phosphorus). Using first-principles calculations and the nonequilibrium Green's function method, the proposed field-effect transistors are characterized. It is found that it is possible to achieve outstanding performance, with high on/off ratios, low subthreshold swings, and high transconductances.