Doo-Won Lee

Bio: Doo-Won Lee is an academic researcher from Sungkyunkwan University. The author has contributed to research in topics: Field-effect transistor & Biosensor. The author has an hindex of 3, co-authored 3 publications receiving 237 citations.

Ultrahigh Responsivity in Graphene–ZnO Nanorod Hybrid UV Photodetector

Abstract: Ultraviolet (UV) photodetectors based on ZnO nanostructure/graphene (Gr) hybrid-channel field-effect transistors (FETs) are investigated under illumination at various incident photon intensities and wavelengths. The time-dependent behaviors of hybrid-channel FETs reveal a high sensitivity and selectivity toward the near-UV region at the wavelength of 365 nm. The devices can operate at low voltage and show excellent selectivity, high responsivity (RI ), and high photoconductive gain (G). The change in the transfer characteristics of hybrid-channel FETs under UV light illumination allows to detect both photovoltage and photocurrent. The shift of the Dirac point (V Dirac ) observed during UV exposure leads to a clearer explanation of the response mechanism and carrier transport properties of Gr, and this phenomenon permits the calculation of electron concentration per UV power density transferred from ZnO nanorods and ZnO nanoparticles to Gr, which is 9 × 10(10) and 4 × 10(10) per mW, respectively. The maximum values of RI and G infer from the fitted curves of RI and G versus UV intensity are 3 × 10(5) A W(-1) and 10(6) , respectively. Therefore, the hybrid-channel FETs studied herein can be used as UV sensing devices with high performance and low power consumption, opening up new opportunities for future optoelectronic devices.

Field-effect transistor with a chemically synthesized MoS2 sensing channel for label-free and highly sensitive electrical detection of DNA hybridization

Abstract: A field-effect transistor (FET) with two-dimensional (2D) few-layer MoS2 as a sensing-channel material was investigated for label-free electrical detection of the hybridization of deoxyribonucleic acid (DNA) molecules. The high-quality MoS2-channel pattern was selectively formedthrough the chemical reaction of the Mo layer with H2S gas. The MoS2 FET was very stable in an electrolyte and inert to pH changes due to the lack of oxygen-containing functionalities on the MoS2 surface. Hybridization of single-stranded target DNA molecules with single-stranded probe DNA molecules physically adsorbed on the MoS2 channel resulted in a shift of the threshold voltage (V th) in the negative direction and an increase in the drain current. The negative shift in V th is attributed to electrostatic gating effects induced by the detachment of negatively charged probe DNA molecules from the channel surface after hybridization. A detection limit of 10 fM, high sensitivity of 17 mV/dec, and high dynamic range of 106 were achieved. The results showed that a bio-FET with an ultrathin 2D MoS2 channel can be used to detect very small concentrations of target DNA molecules specifically hybridized with the probe DNA molecules.

Ultrarapid and ultrasensitive electrical detection of proteins in a three-dimensional biosensor with high capture efficiency

Abstract: The realization of a high-throughput biosensor platform with ultrarapid detection of biomolecular interactions and an ultralow limit of detection in the femtomolar (fM) range or below has been retarded due to sluggish binding kinetics caused by the scarcity of probe molecules on the nanostructures and/or limited mass transport. Here, as a new method for the highly efficient capture of biomolecules at extremely low concentration, we tested a three-dimensional (3D) platform of a bioelectronic field-effect transistor (bio-FET) with vertically aligned and highly dense one-dimensional (1D) ZnO nanorods (NRs) as a sensing surface capped by an ultrathin TiO2 layer for improved electrolytic stability on a chemical-vapor-deposited graphene (Gr) channel. The ultrarapid detection capability with a very fast response time (∼1 min) at the fM level of proteins in the proposed 3D bio-FET is primarily attributed to the fast binding kinetics of the probe–target proteins due to the small diffusion length of the target molecules to reach the sensor surface and the substantial number of probe molecules available on the largely increased surface area of the vertical ZnO NRs. This new 3D electrical biosensor platform can be easily extended to other electrochemical nanobiosensors and has great potential for practical applications in miniaturized biosensor integrated systems.

Electrically-Transduced Chemical Sensors Based on Two-Dimensional Nanomaterials

Abstract: Electrically–transduced sensors, with their simplicity and compatibility with standard electronic technologies, produce signals that can be efficiently acquired, processed, stored, and analyzed. Two dimensional (2D) nanomaterials, including graphene, phosphorene (BP), transition metal dichalcogenides (TMDCs), and others, have proven to be attractive for the fabrication of high–performance electrically-transduced chemical sensors due to their remarkable electronic and physical properties originating from their 2D structure. This review highlights the advances in electrically-transduced chemical sensing that rely on 2D materials. The structural components of such sensors are described, and the underlying operating principles for different types of architectures are discussed. The structural features, electronic properties, and surface chemistry of 2D nanostructures that dictate their sensing performance are reviewed. Key advances in the application of 2D materials, from both a historical and analytical pers...

Chemical sensing with 2D materials

Abstract: During the last decade, two-dimensional materials (2DMs) have attracted great attention due to their unique chemical and physical properties, which make them appealing platforms for diverse applications in opto-electronic devices, energy generation and storage, and sensing. Among their various extraordinary properties, 2DMs possess high surface area-to-volume ratios and ultra-high surface sensitivity to the environment, which are key characteristics for applications in chemical sensing. Furthermore, 2DMs’ superior electrical and optical properties, combined with their excellent mechanical characteristics such as robustness and flexibility, make these materials ideal components for the fabrication of a new generation of high-performance chemical sensors. Depending on the specific device, 2DMs can be tailored to interact with various chemical species at the non-covalent level, making them powerful platforms for fabricating devices exhibiting a high sensitivity towards detection of various analytes including gases, ions and small biomolecules. Here, we will review the most enlightening recent advances in the field of chemical sensors based on atomically-thin 2DMs and we will discuss the opportunities and the challenges towards the realization of novel hybrid materials and sensing devices.

Two-dimensional nanomaterial-based field-effect transistors for chemical and biological sensing

Abstract: Meeting the increasing demand for sensors with high sensitivity, high selectivity, and rapid detection presents many challenges In the last decade, electronic sensors based on field-effect transistors (FETs) have been widely studied due to their high sensitivity, rapid detection, and simple test procedure Among these sensors, two-dimensional (2D) nanomaterial-based FET sensors have been demonstrated with tremendous potential for the detection of a wide range of analytes which is attributed to the unique structural and electronic properties of 2D nanomaterials This comprehensive review discusses the recent progress in graphene-, 2D transition metal dichalcogenide-, and 2D black phosphorus-based FET sensors, with an emphasis on rapid and low-concentration detection of gases, biomolecules, and water contaminants

Biosensors Based on Two-Dimensional MoS2

Abstract: The unique properties of two-dimensional molybdenum disulfide (2D MoS2) have so far led to immense research regarding this material’s fundamentals, applications, and, more recently, its potential for biosensing. 2D MoS2 has properties that make it of great interest for developing biosensors. These properties include large surface area, tunable energy band diagrams, a comparatively high electron mobility, photoluminescence, liquid media stability, relatively low toxicity, and intercalatable morphologies. In this Review, the current progress on 2D MoS2 based biosensors is presented and the prospects for future possibilities of expanding its applications for a variety of biosensing applications are discussed.

The physics and chemistry of graphene-on-surfaces

Abstract: Graphene has demonstrated great potential in next-generation electronics due to its unique two-dimensional structure and properties including a zero-gap band structure, high electron mobility, and high electrical and thermal conductivity. The integration of atom-thick graphene into a device always involves its interaction with a supporting substrate by van der Waals forces and other intermolecular forces or even covalent bonding, and this is critical to its real applications. Graphene films on different surfaces are expected to exhibit significant differences in their properties, which lead to changes in their morphology, electronic structure, surface chemistry/physics, and surface/interface states. Therefore, a thorough understanding of the surface/interface properties is of great importance. In this review, we describe the major “graphene-on-surface” structures and examine the roles of their properties and related phenomena in governing the overall performance for specific applications including optoelectronics, surface catalysis, anti-friction and superlubricity, and coatings and composites. Finally, perspectives on the opportunities and challenges of graphene-on-surface systems are discussed.