Asymmetrically Encapsulated vertical ITO/MoS2/Cu2O photodetector with ultra-high sensitivity

TL;DR

This paper presents an ultra-high sensitivity vertical ITO/MoS2/Cu2O photodetector with encapsulation that achieves record detectivity and responsivity, overcoming persistent photocurrent issues for low-light detection.

Contribution

The study introduces an asymmetrically encapsulated vertical heterojunction photodetector with record-breaking detectivity and responsivity, addressing persistent photocurrent and stability challenges in 2D material photodetectors.

Findings

Achieved a specific detectivity of 3.2x10^14 Jones.

Responsivity of 5.77x10^4 AW-1 at low light levels.

Demonstrated stable operation over many cycles.

Abstract

Strong light absorption, coupled with moderate carrier transport properties, makes two-dimensional (2-D) layered transition metal dichalcogenide (TMD) semiconductors promising candidates for low intensity photodetection applications. However, the performance of these devices is severely bottlenecked by slow response with persistent photocurrent due to long lived charge trapping, and nonreliable characteristics due to undesirable ambience and substrate effects. Here we demonstrate ultra-high specific detectivity (D*) of 3.2x10^14 Jones and responsivity (R) of 5.77x10^4 AW-1 at an optical power density (P_op) of 0.26 Wm-2 and external bias (V_ext) of -0.5 V in an indium tin oxide (ITO)/MoS2/copper oxide (Cu2O)/Au vertical multi-heterojunction photodetector exhibiting small carrier transit time. The active MoS2 layer being encapsulated by carrier collection layers allows us to achieve negligible trap assisted persistent photocurrent and repeatable characteristics over large number of cycles. We also achieved a large D*>10^14 Jones at zero external bias due to the built-in field of the asymmetric photodetector. Benchmarking the performance against existing reports in literature shows a pathway for achieving reliable and highly sensitive photodetectors for ultra-low intensity photodetection applications.