Novel gate-recessed vertical InAs/GaSb TFETs with record high ION of 180 μA/μm at VDS = 0.5 V

Abstract

Vertical tunnel field-effect transistors (TFETs) in which the gate field is aligned with the tunneling direction have been fabricated using a novel gate-recess process, resulting in record on-current. The tunnel junction consists of InAs/GaSb with a broken band alignment. The gate-recess process results in low drain contact and access resistances; together with the favorable broken gap heterojunction, this leads to a record high I_ON of 180 μA/μm at V_DS = V_GS = 0.5 V with an I_ON/I_OFF ratio of 6 ×10³. Both SiN_x passivation and forming gas anneal (FGA) were found to improve the device subthreshold swing (SS), resulting in a SS_MIN of 200 mV/dec at 300 K and 50 mV/dec at 77 K. Capacitance-voltage (C-V) measurements indicate that the device SS performance is limited by interfacial trap density (D_it).