Effects of the thickness and laser irradiation on the electrical properties of e-beam evaporated 2D bismuth

Two-dimensional (2D) bismuth is expected to yield exotic electrical properties for various nanoelectronics, despite the difficulty in large-area preparation and property tuning directly on a device substrate. This work reports electron beam (e-beam) evaporation of large-area 2D bismuth directly on SiO 2 /Si with an electrical conductivity of ∼10 5 S m −1 and a field effect carrier mobility of ∼235 cm 2 V −1 s −1 at room temperature, comparable to those of the molecular beam epitaxy (MBE) counterparts with a similar thickness. Interestingly, the electrical conductivity of 2D bismuth changes when exposed to laser irradiation that possibly induced an increase of the defect concentration, indicating a potential photo-sensor application. The electrical response of 2D bismuth can be modified either by laser irradiation or by varying the layer thickness. Due to the dimension and surface state effects in 2D bismuth, the layer thickness has a strong influence on the carrier concentration and mobility. Inspiringly, a simultaneous increase of the electrical conductivity and the Seebeck coefficient was achieved in 2D bismuth, which is preferred for thermoelectric performance but rarely reported. Our results provided a more accessible platform than MBE to produce decent quality 2D bismuth and similar Xenes with tunable electrical properties for various nanoelectronics. E-beam evaporated uniform 2D bismuth exhibits (thermo)electrical response tunable by either laser irradiation or the layer thickness.