Approaching the Robust Linearity in Dual‐Floating van der Waals Photodiode

Abstract

Two‐dimensional (2D) material photodetectors have gained great attention as potential elements for optoelectronic applications. However, the linearity of the photoresponse is often compromised by the carrier interaction, even in 2D photodiodes. In this study, a new device concept of dual‐floating van der Waals heterostructures (vdWHs) photodiode is presented by employing ambipolar MoTe2 and n‐type MoS2 2D semiconductors. The presence of type II heterojunctions on both sides of channel layers effectively depletes carriers and restricts the photocarrier trapping within the channel layers. As a result, the device exhibits robust linear photoresponse under photovoltaic mode from the visible (405 nm) to near‐infrared (1600 nm) band. With the built‐in electric field of the vdWHs, a linear dynamic range of ≈100 dB, responsivity of ≈1.57 A W−1, detectivity of ≈4.28 × 1011 Jones, and response speed of ≈30 µs are achieved. The results showcase a promising device concept with excellent linearity toward fast and low‐loss detection, high‐resolution imaging, and logic optoelectronics.

Significantly Enhanced Photoresponse of Self-Powered 2D MoS2/WS2 Heterojunction Photodiode via F4-TCNQ Doping

“…Therefore, the doped heterojunction enhances the heterojunction photocurrent. The mechanism of this structure is similar to the work reported by Wei Huang et al to enhance photogenerated carriers in heterojunction by double floating grids and Xia Congxin et al to enhance photogenerated carriers in double van der Waals heterojunctions. , …”

“…Under illumination, photogenerated carriers are formed in both WS 2 and MoS 2 . For the doped heterojunction, under two opposite built-in electric fields, the photogenerated electrons in both WS 2 and the upper layer of MoS 2 enter the lower MoS 2 layer, forming an “electron valley” in the MoS 2 conducting channels . Therefore, the doped heterojunction enhances the heterojunction photocurrent.…”

“…For the doped heterojunction, under two opposite built-in electric fields, the photogenerated electrons in both WS 2 and the upper layer of MoS 2 enter the lower MoS 2 layer, forming an "electron valley" in the MoS 2 conducting channels. 17 Therefore, the doped heterojunction enhances the heterojunction photocurrent. The mechanism of this structure is similar to the work reported by Wei Huang et al to enhance photogenerated carriers in heterojunction by double floating grids and Xia Congxin et al to enhance photogenerated carriers in double van der Waals heterojunctions.…”

“…18 Wei Huang et al reported a dual-floating van der Waals photodiode that achieves robust linearity with a linear dynamic range of 100 dB, a high responsivity of up to 1.57 A W −1 , and a fast response speed of 30 μs. 17 Surface charge transfer doping (SCTD) is a novel doping technique with the advantages of convenience and effectiveness, no damage to the material lattice, and a wide range of dopants. The Fermi energy level difference between the SCTD T h i s c o n t e n t i s dopant and the material determines the direction of the charge transfer.…”

“…However, since such self-powered heterojunction photodetectors usually lack gain and have strong carrier recombination induced by defect states, quantum efficiency is relatively low. Currently, in order to improve the quantum efficiency of self-powered heterojunction photodetectors, researchers have reduced the carrier recombination probability by stacking multilayers of 2D materials to broaden the depletion region and by shortening the photogenerated carrier transport distance through the bottom and top electrodes. , For example, Weida Hu et al reported a fully depleted self-aligned heterosandwiched van der Waals photodetector with a high blackbody peak responsivity of 0.77 A W –1 , a low noise equivalent power of 2.0 × 10 –14 W Hz –1/2 , and an ultrafast response of 4 μs . Wei Huang et al reported a dual-floating van der Waals photodiode that achieves robust linearity with a linear dynamic range of 100 dB, a high responsivity of up to 1.57 A W –1 , and a fast response speed of 30 μs …”