Complementary trilayer−bulk black phosphorus heterojunction tunnel field-effect transistor with subthermionic subthreshold swing

Reductions in transistor size have improved functionality of transistors and lowered costs of electronic processors. However, as transistors decrease in size, quantum tunneling causes increased leakage currents and power consumption. To resolve power consumption issues, tunnel field-effect transistors (TFETs) utilizing band-to-band tunneling (BTBT) have been suggested. Such devices can overcome the 60 mV/dec subthreshold swing (SS) limit that is a disadvantage of conventional metal-oxide-semiconductor field-effect transistors (MOSFETs), but only a limited number of TFETs have achieved this at 300 K. Here, we report complementary trilayer−bulk black phosphorus (BP) heterojunction TFETs with an SS_min of 17.7 mV/dec (21.3 mV/dec) for p-type (n-type) operation. In the same devices, SS ≫ 60 mV/dec is exhibited when BTBT occurs within the trilayer BP, indicating that BTBT between the heterojunction of a trilayer−bulk BP is the key to achieving a subthermionic SS. Our work demonstrates the utility of BP heterojunctions in developing energy-efficient switches.