Blocking transition of SrTiO$_3$ surface dipoles in MoS$_2$/SrTiO$_3$ field effect transistors with counterclockwise hysteresis

TL;DR

This study investigates counterclockwise hysteresis in MoS₂/SrTiO₃ FETs caused by bistable surface dipoles, revealing a temperature-dependent blocking transition that enables heat-assisted memory functionality.

Contribution

It uncovers the role of surface dipole blocking transitions in hysteresis behavior and demonstrates control over threshold voltage for memory applications.

Findings

Hysteresis increases with larger sweep range and slower rate.

Peak hysteresis occurs near 350 K, with transconductance rising above room temperature.

Blocking transition enables threshold voltage control, demonstrating heat-assisted memory.

Abstract

A counterclockwise hysteresis is observed at room temperature in the transfer characteristics of SrTiO$_3$ (STO) gated MoS$_2$ field effect transistor (FET) and attributed to bistable dipoles on the STO surface. The hysteresis is expectedly found to increase with increasing range, as well as decreasing rate, of the gate-voltage sweep. The hysteresis peaks near 350 K while the transconductance rises with rising temperature above the room temperature. This is attributed to a blocking transition arising from an interplay of thermal energy and an energy-barrier that separates the two dipole states. The dipoles are discussed in terms of the displacement of the puckered oxygen ions at the STO surface. Finally, the blocking enables a control on the threshold gate-voltage of the FET over a wide range at low temperature which demonstrates it as a heat assisted memory device.