Thickness-Dependent Carrier Transport Characteristics of a New 2D Elemental Semiconductor: Black Arsenic

2D elemental layered crystals, such as graphene and black phosphorus (B-P), have received tremendous attentions due to their rich physical and chemical properties. In the applications of nanoelectronic devices, graphene shows super high electronic mobility, but it lacks bandgap which impedes development in logical devices. As an alternative, B-P shows high mobility of up to about 1000 cm² V⁻¹ s⁻¹. However, B-P is very unstable and degrades rapidly in ambient conditions. Orthorhombic arsenic (black arsenic; b-As) is the “cousin” of B-P; theoretical prediction shows that b-As also has excellent physical and chemical properties, but there is almost no experimental report on b-As. Herein, it is reported on the unique transport characteristics and stability of monolayer and few-layer b-As crystals which are exfoliated from the natural mineral. The properties of field-effect transistors (FETs) strongly depend on the thickness of crystals. In the monolayer limit, the performance shows relatively high carrier mobilities and large on/off ratios. Moreover, the b-As crystals exhibit a relatively good ambient stability. The few-layer arsenic based FET still function after exposure to air for about one month. Therefore, b-As is expected to be a promising 2D material candidate in nanoelectronic devices.