Fig. 5: As-transferred top-gated Hall device used to perform multi-terminal electrical measurements on air-sensitive black phosphorus (BP).
a Schematic diagram of one-step transfer process to fabricate the top-gated Hall bar of black phosphorus in the glove box. b Diagram of a fully encapsulated Hall-bar device that can effectively isolate water and oxygen in the air, thus allowing for the measurements of the intrinsic properties of the air-sensitive black phosphorus. c Typical OM image of the fabricated top-gated BP hall-bar device. The underlying BP sheet with the thickness of ~11.5 nm was marked out by the dash line. d The I-V curves of the device in (c), preserving linear ohmic contact even after exposed to air for one month. e Longitudinal resistance (Rxx) as a function of temperature (T) under different Vg from 0 to −1.5 V. f Hall resistance (Rxy) as a function of magnetic field (B) under various Vg from 0 to −1.4 V at 300 K. g Corresponding Vg-dependent Hall mobility extracted from (f). The inset is the schematic of the top-gated BP hall-bar device. h Temperature-dependent Rxy-B curves varied from 300 to 50 K under Vg = 0 V. i The extracted temperature-dependent Hall mobility and hole carrier density of black phosphorus before (filled points) and after (open points) exposure to air for 1 week. The red and blue shaded lines are the visual guide for the temperature-dependent mobility and carrier density, respectively.
