A Wafer‐Scale Nanoporous 2D Active Pixel Image Sensor Matrix with High Uniformity, High Sensitivity, and Rapid Switching

Abstract

2D transition‐metal dichalcogenides (TMDs) have been successfully developed as novel ubiquitous optoelectronics owing to their excellent electrical and optical characteristics. However, active‐matrix image sensors based on TMDs have limitations owing to the difficulty of fabricating large‐area integrated circuitry and achieving high optical sensitivity. Herein, a large‐area uniform, highly sensitive, and robust image sensor matrix with active pixels consisting of nanoporous molybdenum disulfide (MoS2) phototransistors and indium–gallium–zinc oxide (IGZO) switching transistors is reported. Large‐area uniform 4‐inch wafer‐scale bilayer MoS2 films are synthesized by radio‐frequency (RF) magnetron sputtering and sulfurization processes and patterned to be a nanoporous structure consisting of an array of periodic nanopores on the MoS2 surface via block copolymer lithography. Edge exposure on the nanoporous bilayer MoS2 induces the formation of subgap states, which promotes a photogating effect to obtain an exceptionally high photoresponsivity of 5.2 × 104 A W−1. A 4‐inch‐wafer‐scale image mapping is successively achieved using this active‐matrix image sensor by controlling the device sensing and switching states. The high‐performance active‐matrix image sensor is state‐of‐the‐art in 2D material‐based integrated circuitry and pixel image sensor applications.

Back-End-of-Line Compatible Large-Area Molybdenum Disulfide Grown on Flexible Substrate: Enabling High-Performance Low-Power Memristor Applications

“…Figure f,g shows high-resolution XPS spectra consisting of a core-level spin–orbit split of Mo 3d along with S 2s. The spin–orbit split of Mo 3d positioned at 229.42 and 232.57 eV corresponds to Mo 4+ 3d 5/2 and Mo 4+ 3d 3/2 , respectively . The doublet peaks from Mo oxidation states are observed at 232.09 and 236.07 eV, ascribed to Mo 6+ 3d 5/2 and Mo 6+ 3d 3/2 , respectively, which may arise from the atmosphere.…”

“…The spin−orbit split of Mo 3d positioned at 229.42 and 232.57 eV corresponds to Mo 4+ 3d 5/2 and Mo 4+ 3d 3/2 , respectively. 29 The doublet peaks from Mo oxidation states are observed at 232.09 and 236.07 eV, ascribed to Mo 6+ 3d 5/2 and Mo 6+ 3d 3/2 , respectively, which may arise from the atmosphere. The spectral signature of S 2p comprises doublet peaks of S 2− 2p 3/2 and S 2− 2p 1/2 centered at 162.31 and 163.51 eV, respectively.…”

“…The annular dark field (ADF) TEM micrograph presented in Figure h depicts the crystal structure of 2-H MoS 2 , and Mo and S atoms are colored according to their intensity profile. The dominant lattice spacings were calculated to be ∼0.27 and ∼0.16 nm for the respective (100) and (110) planes Figure i shows a low-magnification ADF TEM micrograph and corresponding fast Fourier transformation (FFT) pattern (inset of Figure i); transparent artificial shades of colors are used to visualize the nanograins.…”

“…The dominant lattice spacings were calculated to be ∼0.27 and ∼0.16 nm for the respective (100) and (110) planes. 29 Figure 2i shows a lowmagnification ADF TEM micrograph and corresponding fast Fourier transformation (FFT) pattern (inset of Figure 2i); transparent artificial shades of colors are used to visualize the nanograins. Moreover, an ADF-STEM micrograph depicts the multiple nanograins with varying sizes from 2 to 10 nm, which is in accord with the Raman analysis.…”

Synthesis Strategies and Nanoarchitectonics for High‐Performance Transition Metal Dichalcogenide Thin Film Field‐effect Transistors

“…This has enabled the functionalization of more aptamers on MoS 2 semiconductor layers, and the fabrication of ultra-high photoresponsivity (5.2 × 10 4 A • W À 1 ) active-matrix image sensor arrays based on nanoporous MoS 2 thin films. [63] The third strategy for improvement is low-temperature deposition methods that can be used to deposit TMDC thin films on flexible substrates to applicate on wearable devices. However, the process temperature required for TMDC deposition exceeds the melting point of flexible substrates such as polyethylene terephthalate, polyimide, and poly(methyl methacrylate) by 160 ~388 °C, which limits the potential application of TMDC as a semiconductor.…”