Ideal Photodetector Based on WS₂/CuInP₂S₆ Heterostructure by Combining Band Engineering and Ferroelectric Modulation

Abstract

Two-dimensional van der Waals (2D vdW) heterostructure photodetectors have garnered significant attention for their potential applications in next-generation optoelectronic systems. However, current 2D vdW photodetectors inevitably encounter compromises between responsivity, detectivity, and response time due to the absence of multilevel regulation for free and photoexcited carriers, thereby restricting their widespread applications. To address this challenge, we propose an efficient 2D WS 2 /CuInP 2 S 6 vdW heterostructure photodetector by combining band engineering and ferroelectric modulation. In this device, the asymmetric conduction and valence band offsets effectively block the majority carriers (free electrons), while photoexcited holes are efficiently tunneled and rapidly collected by the bottom electrode. Additionally, the ferroelectric CuInP 2 S 6 layer generates polarization states that reconfigure the built-in electric field, reducing dark current and facilitating the separation of photocarriers. Moreover, photoelectrons are trapped during long-distance lateral transport, resulting in a high photoconductivity gain. Consequently, the device achieves an impressive responsivity of 88 A W −1 , an outstanding specific detectivity of 3.4 × 10 13 Jones, and a fast response time of 37.6/371.3 μs. Moreover, the capability of high-resolution imaging under various wavelengths and fast optical communication has been successfully demonstrated using this device, highlighting its promising application prospects in future optoelectronic systems.

Activation of the Photosensitive Potential of 2D GaSe by Interfacial Engineering

“…Figure i presents the time-resolved photocurrent of the GaSe/MoSe 2 device at V ds = 2 V. The rise time (τ rise ) and fall time (τ fall ) are estimated as 112.4 and 426.8 μs, respectively, which is much faster than those of pure MoSe 2 device (Figure S13) and stands out among previously reported 2D photodetectors. − In principle, the τ rise is contingent upon the transport time of photocarriers, while the τ fall is mainly influenced by the recombination process of photocarriers. ,, Within the GaSe/MoSe 2 device, the variable transport and recombination times of the photocarriers result in distinct τ rise and τ fall . Similar observations have been documented in the literature concerning 2D photodetectors. , In addition, the underlying GaSe mitigates adverse effects on the SiO 2 substrate and substantially improves the carrier mobility, which accelerates the transportation of photocarriers. Moreover, E bi at the GaSe/MoSe 2 heterointerface separates photocarriers and diminishes their recombination.…”

Sandwiched WS2/MoTe2/WS2 Heterostructure with a Completely Depleted Interlayer for a Photodetector with Outstanding Detectivity

“…The thicknesses of top WS 2 , middle MoTe 2, and bottom WS 2 are 27.3, 23.5, and 33.1 nm, respectively. The selection of slightly thick 2D materials aims to better absorb the incident light. , Moreover, multilayered 2D materials can mitigate the adverse effects from the substrate and unleash the intrinsic photoresponse properties of 2D materials . The presence of the bottom electrode enables further photon absorption through reflection of incident light, thereby enhancing the interaction between light and the 2D heterostructure.…”