Vertical-Tunnel Field-Effect Transistor Based on a Silicon–MoS₂ Three-Dimensional–Two-Dimensional Heterostructure

We present a tunneling field-effect transistor based on a vertical heterostructure of highly p-doped silicon and n-type MoS2. The resulting p–n heterojunction shows a staggered band alignment in which the quantum mechanical band-to-band tunneling probability is enhanced. The device functions in both tunneling transistor and conventional transistor modes, depending on whether the p–n junction is forward or reverse biased, and exhibits a minimum subthreshold swing of 15 mV/dec, an average of 77 mV/dec for four decades of the drain current, a high on/off current ratio of approximately 107 at a drain voltage of 1 V, and fully suppressed ambipolar behavior. Furthermore, low-temperature electrical measurements demonstrated that both trap-assisted and band-to-band tunneling contribute to the drain current. The presence of traps was attributed to defects within the interfacial oxide between silicon and MoS2