Low 3 volt operation of 2D MoTe2 ferroelectric memory transistors with ultrathin pinhole-free P(VDF-TrFE) crystalline film

Abstract

Organic ferroelectric crystalline polymer, P(VDF-TrFE) has attracted broad attentions due to its lead-free benefits and process convenience. However, it has a long-standing drawback, its process limit in crystalline film thickness, whose minimum is almost fixed as ∼100 nm. Hence, operation voltage of any P(VDF-TrFE)-based ferroelectric memory field-effect transistors (FeFETs) has always been over 10 V. Here, innovatively thinned ∼20 nm P(VDF-TrFE) crystalline layers are fabricated on Pt and Au gate, empowering FeFETs with two dimensional (2D) MoTe2 channel to operate under minimum 3 V pulse. Such thin crystalline layer is achieved through spin-coating after initial growth of 5 nm-thin crystalline seed layer, P(VDF-TrFE)-brush. This ultrathin P(VDF-TrFE)-brush effectively inhibits the de-wetting problem of P(VDF-TrFE)-solution during spin-coating, leading to good surface-energy matching and pinhole-free conformal coating of classical P(VDF-TrFE). As a result, 3–4 V pulse operations of p-MoTe2 nonvolatile memory FETs are nicely realized without leakage current loss. These numbers may be regarded as one of the lowest values in report.