Figure 2: Bandgap tuning in a 4 nm-thick BP film.
From: Efficient electrical control of thin-film black phosphorus bandgap
(a) The 4 nm-thick BP film conductance as a function of top gate bias (VTG) at different static back gate biases (VBG) from −25 to 25 V. (b) The minimum conductance at the charge-neutrality point as a function of external displacement field. Inset: the top gate bias at which the minimum conductance occurs (VTM) as a function of the back gate bias (VBG). The linear relation indicates the effective doping compensation by the back and top biases, leading to an insulating state at the charge-neutrality. (c) Solid lines: The calculated bandgap tuning properties for BP films consisting of 4, 5, 6, 7, 16, 17, 18 and 19 layers using a tight-binding model built on the DFT. The BP films with different thicknesses exhibit distinctively different tuning properties. Purple dots: the measured bandgap tuning results for the 4 nm-thick BP film (∼7 layers).
