Molybdenum disulfide (MoS) field-effect transistor (FET)-based biosensors have attracted significant attention as promising candidates for highly sensitive, label-free biomolecule detection devices. In this paper, toward practical applications of biosensors, we demonstrate reliable and quantitative detection of a prostate cancer biomarker using the MoS FET biosensor in a nonaqueous environment by reducing nonspecific molecular binding events and realizing uniform chemisorption of anti-PSA onto the MoS surface. A systematic and statistical study on the capability of the proposed device is presented, and the biological binding events are directly confirmed and characterized through intensive structural and electrical analysis. Our proposed biosensor can reliably detect various PSA concentrations with a limit of 100 fg/mL. Moreover, rigorous theoretical simulations provide a comprehensive understanding of the operating mechanism of the MoS FET biosensors, and further suggests the enhancement of the sensitivity through engineering device design parameters.
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.
PtSe 2 , a new family of transition metal dichalcogenides, has been explored for electronic device applications using density functional theory (DFT) and non-equilibrium Green's function (NEGF) within the third nearest neighbor tight-binding approximation. Interestingly, despite its small effective mass (m e * as low as 0.21m 0 ; m 0 being electron rest mass), PtSe 2 has large density of states (DOS) due to its unique six-valley conduction band within the first Brillouin zone, unlike MoX 2 family. This has direct impacts on the device characteristics of PtSe 2 field-effect transistors, resulting in superior on-state performance (30% higher on current and transconductance) as compared to the MoSe 2 counterpart. Our simulation shows that PtSe 2 device with a channel longer than 15 nm exhibits near-ideal subthreshold swing, and sub-100 mV/V of drain-induced barrier lowering can be achieved with an aggressively scaled gate oxide, demonstrating new opportunities for electronic devices with novel PtSe 2 .
Indirect bandgap of multilayer molybdenum disulfide has been recognized as a major hindrance to high responsivity of MoS2 phototransistors. Here, to overcome this fundamental limitation, we propose a structural engineering of MoS2 via nano-patterning using block copolymer lithography. The fabricated nanoporous MoS2, consisting of periodic hexagonal arrays of hexagon nanoholes, includes abundant edges having a zigzag configuration of atomic columns with molybdenum and sulfur atoms. These exposed zigzag edges are responsible for multiple trap states in the bandgap region, as confirmed by photo-excited charge-collection spectroscopy measurements on multilayer nanoporous MoS2 phototransistors, showing that in-gap states only near the valence band can result in a photogating effect. The effect of nano-patterning is therefore to significantly enhance the responsivity of multilayer nanoporous MoS2 phototransistors, exhibiting an ultra-high photoresponsivity of 622.2 A W−1. Our nano-patterning of MoS2 for photosensing application paves a route to structural engineering of two-dimensional materials for highly sensitive and responsive optoelectronic devices.
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