  The discovery of graphene and the related fascinating capabilities have
triggered an unprecedented interest in inorganic two-dimensional (2D)
materials. Despite the impressive impact in a variety of photonic applications,
the absence of energy gap has hampered its broader applicability in many
optoelectronic devices. The recent advance of novel 2D materials, such as
transition-metal dichalcogenides or atomically thin elemental materials, (e.g.
silicene, germanene and phosphorene) promises a revolutionary step-change. Here
we devise the first room-temperature Terahertz (THz) frequency detector
exploiting few-layer phosphorene, e.g., a 10 nm thick flake of exfoliated
crystalline black phosphorus (BP), as active channel of a field-effect
transistor (FET). By exploiting the direct band gap of BP to fully switch
between insulating and conducting states and by engineering proper antennas for
efficient light harvesting, we reach detection performance comparable with
commercial detection technologies, providing the first technological
demonstration of a phosphorus-based active THz device.
