An all two-dimensional vertical heterostructure graphene/CuInP₂S₆/MoS₂for negative capacitance field effect transistor

As scaling down the size of metal oxide semiconductor field-effect transistors (FETs), power dissipation has become a major challenge. Lowering down the sub-threshold swing (SS) is known as an effective technique to decrease the operating voltage of FETs and hence lower down the power consumption. However, the Boltzmann distribution of electrons (so-called 'Boltzmann tyranny') implements a physical limit to the SS value. Use of negative capacitance (NC) effect has enabled a new path to achieve a low SS below the Boltzmann limit (60 mV dec-1 at room temperature). In this work, we have demonstrated a NC-FET from an all two-dimensional (2D) metal ferroelectric semiconductor (MFS) vertical heterostructure: Graphene/CuInP2S6/MoS2. The negative capacitance from the ferroelectric CuInP2S6 has enabled the breaking of the 'Boltzmann tyranny'. The heterostructure based device has shown steep slopes switching below 60 mV dec-1 (lowest to < 10 mV dec-1) over 3 orders of source-drain current, which provides an avenue for all 2D material based steep slope FETs.