Heekyeong Park

The unique electrical and optical properties of transition metal dichalcogenides (TMDs) make them attractive nanomaterials for optoelectronic applications, especially optical sensors. However, the optical characteristics of these materials are dependent on the number of layers. Monolayer TMDs have a direct bandgap that provides higher photoresponsivity compared to multilayer TMDs with an indirect bandgap. Nevertheless, multilayer TMDs are more appropriate for various photodetection applications

The ubiquitous field-effect transistor (FET) is widely used in modern digital integrated circuits, computers, communications, sensors, and other applications. However, reliable biological FET (bio-FET) is not available in real life due to the rigorous requirement for highly sensitive and selective bio-FET fabrication, which remains a challenging task. Here, we report an ultrasensitive and selective bio-FET created by the nanorings of molybdenum disulfide (MoS₂) nanopores inspired by n

Molybdenum disulfide (MoS₂) 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 MoS₂ FET biosensor in a nonaqueous environment by reducing nonspecific molecular binding events and realizing uniform chemisor

Two-dimensional molybdenum disulfide (MoS₂) has emerged as a promising material for optoelectronic applications because of its superior electrical and optical properties. However, the difficulty in synthesizing large-scale MoS₂ films has been recognized as a bottleneck in uniform and reproducible device fabrication and performance. Here, we proposed a radio-frequency magnetron sputter system, and post-treatments of electron beam irradiation and sulfurization to obtain large

The detection of circulating protein (CP) is very important for the diagnosis and therapeutics of cancer. Conventional techniques based on a specific antibody-antigen interaction are still lacking because of a shortage of cost effectiveness, complicated sandwich structure and tagging process, and inconsistent detection of CP due to the inherent instability of antibodies. Herein, we demonstrate a hybrid device consisting of two-dimensional (2D) nanoscale molybdenum disulfide (MoS₂) fie

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

Flexible sensors connected to cell phones are a promising technology that can aid in continuously monitoring signals in our daily lives, such as an individual's health status and information from buildings, farms, and industry. Among such signals, real-time humidity monitoring is crucial to a comfortable life, as human bodies, plants, and industrial environments require appropriate humidity to be maintained. We propose a hydrophilic polytetrafluoroethylene (H-PTFE)-based flexible humidity sensor

Abstract Indirect bandgap of multilayer molybdenum disulfide has been recognized as a major hindrance to high responsivity of MoS 2 phototransistors. Here, to overcome this fundamental limitation, we propose a structural engineering of MoS 2 via nano-patterning using block copolymer lithography. The fabricated nanoporous MoS 2 , consisting of periodic hexagonal arrays of hexagon nanoholes, includes abundant edges having a zigzag configuration of atomic columns with molybdenum and sulfur atoms. T

Molybdenum disulfide (MoS2), a transition metal dichalcogenide, has been demonstrated as a promising substitute for noble metal catalysts in the hydrogen evolution reaction (HER). However, its practical application is limited by the inert nature of the basal planes. In this study, we developed a highly active and robust MoS2 catalyst with uniform triangular nanoholes on its basal plane via nanoscale patterning. The process successfully created edge defects with a Mo-terminated zigzag configurati

Abstract Field‐effect transistors‐based biosensors (bio‐FETs) have been considered an important technology for label‐free and ultrasensitive point‐of‐care diagnostics. However, practical applications using bio‐FETs are limited due to the trade‐off between sensing reliability and sensitivity. This study suggests a reliable and sensitive bio‐FETs based on nanoporous molybdenum disulfide (MoS 2 ) channels encapsulated by a non‐planar high‐k aluminum oxide (Al 2 O 3 ) dielectric layer. Nanoporous Mo

Abstract Nanoporous patterning of two-dimensional materials using block copolymer lithography has drawn much attention. Lateral edge exposures made by the nanoporous patterning provide electrical and optical characteristics that are different from the original materials. However, nanopatterning processes inevitably generate edge exposure and surface defects that may result in poor reliability and reproducibility of the devices. In this study, we propose a reliable method to passivate nanoporous

<title>Abstract</title> Absence of functional groups on the basal plane of molybdenum disulfide (MoS₂) significantly hinders the performance of MoS₂ field-effect transistor-based biosensor (bio-FET). We present a novel method for creating nano-scale holes on a MoS₂ channel using block copolymer lithography, where the edge areas on the nanoholes were used to form covalent linkage between the capture molecules of cortisol aptamer and the MoS₂ channel. Th

Image Sensor Devices In article number 2210715, Luke P. Lee, Youngki Yoon, Sunkook Kim, and co-workers present a novel active pixel image sensor matrix using large-area nanoporous MoS2, which achieves ultrahigh sensitivity and fast switching ability. This study represents significant conceptual and practical advancements in image sensor devices based on 2D materials, including wafer-scale synthesis, nanoscale patterning, rigorous modeling, and optoelectrical analysis. These advancements could po