The emergence of rapidly expanding infectious diseases such as coronavirus (COVID-19) demands effective biosensors that can promptly detect and recognize the pathogens. Field-effect transistors based on semiconducting two-dimensional (2D) materials (2D-FETs) have been identified as potential candidates for rapid and label-free sensing applications. This is because any perturbation of such atomically thin 2D channels can significantly impact their electronic transport properties. Here, we report the use of FET based on semiconducting transition metal dichalcogenide (TMDC) WSe 2 as a promising biosensor for the rapid and sensitive detection of SARS-CoV-2 in vitro . The sensor is created by functionalizing the WSe 2 monolayers with a monoclonal antibody against the SARS-CoV-2 spike protein and exhibits a detection limit of down to 25 fg/μL in 0.01X phosphate-buffered saline (PBS). Comprehensive theoretical and experimental studies, including density functional theory, atomic force microscopy, Raman and photoluminescence spectroscopies, and electronic transport properties, were performed to characterize and explain the device performance. The results demonstrate that TMDC-based 2D-FETs can potentially serve as sensitive and selective biosensors for the rapid detection of infectious diseases.

Two-dimensional (2D) layered materials including transition metal dichalcogenides (TMDCs) have recently been at the heart of the quantum materials and information sciences research due to unusual properties associated with their firmly defined dimensionalities. Many efforts have focused on developing new methods for the accelerated growth and discovery of 2D materials, including physical and chemical vapor deposition techniques. However, the synthesis of these multi-component crystals in the gas phase has been extremely challenging due to complex and uncontrolled gas-phase reactions and flow dynamics. Here, we demonstrate a novel laser-assisted synthesis technique (LAST), which significantly reduces the existing growth complexities and notably accelerates the growth of 2D materials. This approach facilitates the growth of various 2D materials directly from stoichiometric powders by laser vaporization process. We show that directed laser heating allows pressure-independent decoupling of the growth and evaporation kinetics enabling the use of stoichiometric powder as precursors for the growth of high-quality 2D materials including MoS 2 , MoSe 2 , WSe 2 , and WS 2 . A comprehensive experimental study was conducted to identify the system behavior, including the evaporation and growth parameters as well as the processproperty relationships. This method presents a general yet simple approach for accelerating the discovery of emerging quantum materials.

This work reports the interfacial thermal conductance (G) and radiative recombination efficiency (β), also known as photoluminescence quantum yield (PL QY), of monolayer WSe2 flakes supported by fused silica substrates via energy-transport state-resolved Raman (ET-Raman). This is the first known work to consider the effect of radiative electron–hole recombination on the thermal transport characteristics of single-layer transition-metal dichalcogenides (TMDs). ET-Raman uses a continuous-wave laser for steady-state heating as well as nanosecond and picosecond lasers for transient energy transport to simultaneously heat the monolayer flakes and extract the Raman signal. The three lasers induce distinct heating phenomena that distinguish the interfacial thermal conductance and radiative recombination efficiency, which can then be determined in tandem with three-dimensional (3D) numerical modeling of the temperature rise from respective laser irradiation. For the five samples measured, G is found to range from 2.10 ± 0.14 to 15.9 ± 5.0 MW m–2 K–1 and β ranges from 36 ± 6 to 65 ± 7%. These values support the claim that interfacial phenomena such as surface roughness and two-dimensional (2D) material–substrate bonding strength play critical roles in interfacial thermal transport and electron–hole recombination mechanisms in TMD monolayers. It is also determined that low-level defect density enhances the radiative recombination efficiency of single-layer WSe2.

Excitons in two-dimensional transition metal dichalcogenide monolayers (2D-TMDs) are of essential importance due to their key involvement in 2D-TMD-based applications. For instance, exciton dissociation and exciton radiative recombination are indisponsable...