Fig. 3: Fundamental electrical transport properties of BP.

a Calculated (top) and ARPES-mapped (below) results regarding the band structure of bulk black phosphorus. b PL spectra for monolayer phosphorene and bulk black phosphorus samples. The bandgap of monolayer black phosphorene can be concluded to be ~1.45 eV accordingly. c, d Thickness (layer) and temperature dependence of the conductivity measured as a function of gate bias, respectively. e, f Carrier transport and exciton diffusion characteristic of 2-nm amorphous BP ultrathin film, respectively, demonstrating through FET transfer curve and spatiotemporal differential reflection signal. g Angular-dependent performance on drain current and transconductance of the eight-electrodes devices based on few-layer black phosphorus. The inset shows schematic of the new-designed device with eight electrodes in a circle for investigating the anisotropy transport features of BP. h Planar view of the squared electron wavefunction for the exciton at ground state in the single-layer black phosphorus. Images of a, c, and d used with permission from Springer Nature⁶³. Images of b and g adapted with permission from ref. ²⁷ copyright 2014, American Chemical Society. Image of e used with permission from John Wiley and Sons⁷⁴. Image of f © IOP Publishing. Reproduced with permission from ref. ⁷⁵. All rights reserved. Images of h used with permission from Springer Nature⁸¹.