Device design of vertical nanowire III-V heterojunction TFETs for performance enhancement

In this paper, we analyze the heterojunction GaAs _0.4 Sb _0.6 /In _0.65 Ga _0.35 As TFET with vertical nanowire structure and non-uniform diameter design (V-NW TFET with non-uniform diameter). A thin channel layer (Ti) is inserted between the gate and source regions for improving the on currents, and the non-uniform diameter thickness is used for suppressing the leakage current (I _min ). The bandgap widening induced by quantum confinement is considered in this work. The leakage current can be suppressed by using thinner diameter thickness of the drain/channel junction (T _DC ), and the gate-to-drain underlap design is used to further reduce the ambipolar leakage. The impacts of Ti, T _DC , source and drain doping concentrations, and gate-to-source overlap length (L _ovs ) on the V-NW TFET have been investigated. Compared with the ultra-thin body (UTB) TFET, the proposed V-NW TFET with non-uniform diameter (thin T _DC ) exhibits 2 times larger I _on (236 μA/μm) due to the increased line tunneling area, and 59.8 times lower leakage current (5.5×10 ^-10 μA/μm).