Gate-thickness-dependent nonvolatile modulation of monolayer MoS2 channels by epitaxial Al0.7Sc0.3N ferroelectric gates

Ferroelectric wurtzite AlScN has emerged as a non-oxide ferroelectric compatible with nitride and semiconductor device processing, but how epitaxial AlScN ferroelectric-gate thickness affects nonvolatile electrostatic modulation and reliability in two-dimensional semiconductor channels remains to be clarified. Here, nonvolatile field-effect control is demonstrated in monolayer MoS2 transistors gated by epitaxial Al0.7Sc0.3N (ASN) thin films with different gate thicknesses. The ASN layers used in this work were previously shown to exhibit c-axis-oriented epitaxial growth and robust ferroelectric polarization, whereas the present study focuses on their device-level integration with MoS2 channels. Raman spectroscopy verifies the monolayer nature of the MoS2 channel. Depending on the remanent polarization direction of the ASN gate, the MoS2 channel is modulated between depletion- and electron-accumulation-type conductance states, producing a clear hysteretic field-effect response. The devices exhibit a large zero-gate-field ON/OFF current ratio, reaching approximately 2.2 × 108 for the 50 nm ASN gate, together with stable retention up to 105 s. These results identify epitaxial ASN ferroelectric-gate thickness as a key device-physics parameter that controls the balance between nonvolatile electrostatic channel modulation and cycling reliability in non-oxide ferroelectric/2D semiconductor memory devices.