Promoting the Performance of 2D Material Photodetectors by Dielectric Engineering

Abstract

Taking advantages of the dangling-bondfree surface, excellent in-plane carrier mobility, pronounced quantum confinement effect, thickness/strain-sensitive physical properties, outstanding mechanical flexibility, and strong light-matter interactions, 2DMs have demonstrated enormous potential in the realm of photo detection. [2][3][4][5] For example, in 2016, Koppens et al. prepared an ultrafast photodetector based on a vertical graphene/ MoSe 2 /graphene sandwich structure. [6] Since the transport path of photocarriers is down to a few molecule layers, the transit time is extremely limited. As a result, the response time of the device with a MoSe 2 channel thickness of 2.2 nm is merely 5.5 ps. In 2020, Maiti et al. achieved the expansion of effective wavelength range of 2DM photodetectors by leveraging strain engineering. [7] The bandgap of 4%-strained 2D MoTe 2 markedly shrinks by ≈0.24 eV as compared to unstrained MoTe 2 (from 1.04 to 0.8 eV). As a result, the strained 2D MoTe 2 photodetector demonstrates distinct photoresponse to illumination of telecommunication wavelengths. Recently, by exploiting graphene as electrodes, connecting lines as well as photosensitive channels, Norris et al. have fabricated "all-graphene" photo detectors, which simultaneously enable light detection and high transparency. [8] Based on such functional units distributed along the optical path, a proof-of-concept single-pixel focal stack light field camera is successfully built and the key operating principle to perform optical ranging is demonstrated.In spite of remarkable progress, the atomic-scale thicknessinduced low light absorption and limited carrier lifetime have been two ever-present limiting factors hindering the effective accumulation of photocarriers and thus curtailing the further breakthrough of the performance of 2DM photodetectors. Various strategies have been developed to address these predicaments. On the one hand, a variety of optical micro-/nanostructures, including plasmonic antenna, [9] optical waveguide, [10] and optical cavity, [11] have been designed to enhance the light harvesting. However, noble metal micro-/nanostructures suffer from high material cost and limited resonant range, while the Low light absorption and limited carrier lifetime are two limiting factors hampering the further breakthrough of the performance of 2D materials (2DMs)-based photodetectors. This study proposes an ingenious dielectric engineering strategy toward boosting the photosensitivity. Periodic dielectric structures (PDSs), including SiO 2 /h-BN, SiO 2 /Al 2 O 3 , and SiO 2 /SrTiO 3 (STO), are exploited to couple with 2D photosensitive channels (denoted as PDS- 2DMs). The responsivity, external quantum efficiency, and detectivity of an optimized SiO 2 /STO (300 nm) -WSe 2 photodetector reach 89081 A W −1 , 2.7 × 10 7 %, and 1.8 × 10 13 Jones, respectively. These performance metrics are orders of magnitude higher than a pristine WSe 2 photodetector, enabling reliable sub-1 pW weak light detection. Based on systematic characterizatio...

High-performance hierarchical O-SnS/I-ZnIn2S4 photodetectors by leveraging the synergy of optical regulation and band tailoring

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Pulsed‐Laser‐Deposition Fabricated ZnIn2S4 Photodetectors with Excellent ON/OFF Switching Characteristics toward High‐Temperature‐Resistant Photodetection Applications

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In situ integration of Te/Si 2D/3D heterojunction photodetectors toward UV-vis-IR ultra-broadband photoelectric technologies

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