Highly sensitive and system integrable gas sensors play a significant role in industry and daily life, and MoS2 has emerged as one of the most promising two-dimensional nanomaterials for gas sensor technology. In this study, we demonstrate a scalable and monolithically integrated active-matrix gas sensor array based on large-area bilayer MoS2 films synthesized via two-successive steps: radio-frequency magnetron sputtering and thermal sulfurization. The fabricated thin-film transistors exhibit consistent electrical performance over a few centimeters area and resulting gas sensors detect NO2 with ultra-high sensitivity across a wide detection range, from 1 to 256 ppm. This is due to the abundant grain boundaries of the sputtered MoS2 channel, which perform as active sites for absorption of NO2 gas molecules. The demonstrated active-matrix gas sensor arrays display good switching capabilities and are anticipated to be readily integrated with additional circuitry for different gas sensing and monitoring applications.

The size of the advanced Cu interconnects has been significantly reduced, reaching the current 7.0 nm node technology and below. With the relentless scaling-down of microelectronic devices, the advanced Cu interconnects thus requires an ultrathin and reliable diffusion barrier layer to prevent Cu diffusion into the surrounding dielectric. In this paper, amorphous carbon (a-C) layers of 0.75–2.5 nm thickness have been studied for use as copper diffusion barriers. The barrier performance and thermal stability of the a-C layers were evaluated by annealing Cu/SiO2/Si metal-oxide-semiconductor (MOS) samples with and without an a-C diffusion barrier at 400 °C for 10 h. Microstructure and elemental analysis performed by transmission electron microscopy (TEM) and secondary ion mass spectroscopy showed that no Cu diffusion into the SiO2 layer occurred in the presence of the a-C barrier layer. However, current density-electric field and capacitance–voltage measurements showed that 0.75 and 2.5 nm thick a-C barriers behave differently because of different microstructures being formed in each thickness after annealing. The presence of the 0.75 nm thick a-C barrier layer considerably improved the reliability of the fabricated MOS samples. In contrast, the reliability of MOS samples with a 2.5 nm thick a-C barrier was degraded by sp2 clustering and microstructural change from amorphous phase to nanocrystalline state during annealing. These results were confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy and TEM analysis. This study provides evidence that an 0.75 nm thick a-C layer is a reliable diffusion barrier.

Rapid growth of high-crystalline MoSe2 nanosheets with grain size of up to ∼100 μm and yield of milligrams per hour.