The Influence of Dimensionality on the Charge Density Wave Transition and Its Application on Mid-infrared Photodetection

TL;DR

This paper demonstrates a high-performance mid-infrared photodetector based on a quasi-1D charge density wave material, revealing the critical influence of dimensionality on CDW phase transition and device efficiency.

Contribution

It introduces a novel application of quasi-1D (TaSe4)2I for broadband photodetection, highlighting the role of dimensionality in enhancing device performance.

Findings

Achieved high photo responsivity of 1.18e3 A/W in mid-infrared.

Observed lower dark current density due to pseudo gap from 1D Luttinger liquid state.

Demonstrated ultrasensitive switching linked to Frohlich superconductivity.

Abstract

Two-dimensional charge density wave (CDW) materials received much attention for high responsivity and broadband photodetection in recent years, due to their collective electron transport and narrow bandgap. However, the high dark current density problem hinders their real application. Here we report a sharp CDW transition in quasi-1D (TaSe4)2I, and apply it for broadband photodetection. Especially at mid-infrared region, the device shows both high photo responsivity of 1.18e3 A/W and large light on-off ratio of 80, which is superior than 2D CDW TaS2 and most reported low-dimensional materials. The fact for such high performance lies on two aspects. One is the much lower dark current density resulted from the pseudo gap associated with 1D Luttinger liquid state, which is supported by finite size scaling of nonlinear I-V at variable temperatures and occurrence of 1D structural phase transition consolidated by In-situ Raman spectroscopy. The other is the high photocurrent associated with the Frohlich superconductivity state, manifested by an ultrasensitive switching, which can be only accessible in 1D CDW materials, in agreement with our density functional theory calculation. Our work thus reveals the pivotal role of dimensionality in CDW phase transition, and paves a way for implementing highly sensitive broadband photodetector.