A transverse tunnelling field-effect transistor made from a van der Waals heterostructure

Semiconductor devices that rely on quantum tunnelling could be of use in logic, memory and radiofrequency applications. Tunnel devices that exhibit negative differential resistance typically follow an operating principle in which the tunnelling current contributes directly to the drive current. Here, we report a tunnelling field-effect transistor made from a black phosphorus/Al2O3/black phosphorus van der Waals heterostructure in which the tunnelling current is in the transverse direction with respect to the drive current. Through an electrostatic effect, this tunnelling current can induce a drastic change in the output current, leading to a tunable negative differential resistance with a peak-to-valley ratio of more than 100 at room temperature. Our device also exhibits abrupt switching, with a body factor (the relative change in gate voltage with respect to that of the surface potential) that is one-tenth of the Boltzmann limit for conventional transistors across a wide temperature range. A black phosphorus/Al2O3/black phosphorus heterostructure can be used to create a tunnel field-effect transistor in which the tunnelling current is in the transverse direction with respect to the drive current, leading to abrupt switching and a negative differential resistance with a peak-to-valley ratio of more than 100 at room temperature.