Vertically Stacked Broadband GNIF‐MoS2/p‐Ge Photodetector for Dark Current Suppression, High Photoresponse, and Ultrafast Transient Response

The proposed model structure, featuring a gold (Au) nano‐island film (GNIF) integrated with a vertically stacked van der Waals heterojunction and offering an elegant platform for high‐performance, efficient, and sensitive photodetection across a broad spectral range, is designated as GNIF‐MoS₂/p‐Ge(...

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Published in:Advanced optical materials 2024-11, Vol.12 (31), p.n/a
Main Authors: Pandey, Rajiv Kumar, Choi, Hwayong, Kim, Young‐Hoon, Jeong, Subin, Kim, Yeji, Heo, Junseok
Format: Article
Language:English
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Summary:The proposed model structure, featuring a gold (Au) nano‐island film (GNIF) integrated with a vertically stacked van der Waals heterojunction and offering an elegant platform for high‐performance, efficient, and sensitive photodetection across a broad spectral range, is designated as GNIF‐MoS₂/p‐Ge(MoS2 = Molybdenum disulfide, p‐Ge = p type germanium). The GNIF is fabricated via ultrathin film deposition, based on the surface dewetting properties of MoS2. The as‐fabricated photodetector (PD), offering ≈20 times reduction in dark current and characterized by wavelength‐dependent high responsivity (R(λ)), photoconductive gain (G(λ)), and detectivity (D(λ)), respond to a broad spectral range from visible light (400 nm) to short wave infrared (SWIR) (1600 nm). The ultrahigh transient response (τr) is found to be ≈2.5 and 16 µs for the 470 (visible light) and 1550 (SWIR) nm wavelengths, respectively, resulting in 3‐dB bandwidths of up to ≈48 kHz, which is considered high for such devices. To understand the inherent mechanisms of broadband detection and the high photoresponse and ultrafast transient response of PDs, a meticulous investigation is conducted on the wavelength‐dependent behaviors, depletion width changes, and material properties. The results provide valuable insights and a basis for the construction of suitable PDs based on nanometer‐thin metal films, 2D semiconductors, and a 3D hybrid structure. In this work, the successful fabrication and exploration of a GNIF‐MoS2/p‐Ge vertically stacked van der Waals heterojunction (vdWH) device, aimed at understanding the broadband detection capabilities and the effect of GNIF on crucial parameters of photodetectors (PDs), including dark current (Id), photoconducting gain (G(λ)), responsivity (R(λ)), and detectivity (D(λ)), transient response(ττr) under different wavelengths of light, is presented.
ISSN:2195-1071
2195-1071
DOI:10.1002/adom.202401363