Gate controlled large resistance switching driven by charge density wave in 1T-TaS2/2H-MoS2 heterojunction

TL;DR

This paper demonstrates how a gate voltage can significantly modulate and amplify resistivity switching in a 1T-TaS2/2H-MoS2 heterojunction driven by charge density wave phase transitions, enabling advanced device functionalities.

Contribution

It reveals that external gating can control and enhance CDW-induced resistivity switching via Schottky barrier modulation in a heterojunction, a novel approach for device applications.

Findings

Gate voltage modulates Schottky barrier height at the interface.

Resistivity switching is amplified up to 17.3 times with gating.

Electrical Mott gap in TaS2 estimated at ~71 meV.

Abstract

1T-TaS2 is a layered material that exhibits charge density wave (CDW) induced distinct electrical resistivity phases and has attracted a lot of attention for interesting device applications. However, such resistivity switching effects are often weak, and cannot be modulated by an external gate voltage - limiting their widespread usage. Using a back-gated 1T-TaS2/2H-MoS2 heterojunction, here we show that the usual resistivity switching in TaS2 due to different phase transitions is accompanied with a surprisingly strong modulation in the Schottky barrier height (SBH) at the TaS2/MoS2 interface - providing an additional knob to control the degree of the phase-transition-driven resistivity switching by an external gate voltage. In particular, the commensurate (C) to triclinic (T) phase transition results in an increase in the SBH owing to a collapse of the Mott gap in TaS2. The change in SBH allows us to estimate an electrical Mott gap opening of ~71 +/- 7 meV in the C phase of TaS2. On the other hand, the nearly-commensurate (NC) to incommensurate (IC) phase transition results in a suppression in the SBH, and the heterojunction shows a gate-controlled resistivity switching up to 17.3, which is ~14.5 times higher than that of standalone TaS2. The findings mark an important step forward showing a promising pathway to externally control as well as amplify the CDW induced resistivity switching. This will boost device applications that exploit these phase transitions, such as ultra-broadband photodetection, negative differential conductance, fast oscillator and threshold switching in neuromorphic circuits.