Novel Strategy for One-Pot Synthesis of Gold Nanoplates on Carbon Nanotube Sheet As an Effective Flexible SERS Substrate

In this work, we demonstrate a novel route for one-pot synthesis of two-dimensional gold nanoplates (2-D AuNPLs) on carbon nanotube (CNT) sheet. Well-defined AuNPLs are grafted onto CNT sheet via a facile hydrothermal reduction process, during which bromine ions are employed as the surfactant for gold anisotropic growth. Scanning electron microscopy (SEM) shows large-scale AuNPLs with micrometer-scaled length and sub-100 nm thickness are deposited uniformly on the CNT sheet. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results confirm the synthesized AuNPLs are single-crystalline with preferential {111} orientation. Based on the CNT sheet/AuNPLs hybrid, we have fabricated a flexible surface-enhanced Raman scattering (SERS) substrate, which can effectively detect the analyte Rhodamine 6G (Rh6G) at the concentration as low as 1 × 10^–7 M. The excellent SERS performance of this novel flexible substrate is mainly attributed to nanoscaled gaps between the neighbors, large surface area with roughness, and their sharp edges and corners

Quasi-Two-Dimensional Metal Oxide Semiconductors Based Ultrasensitive Potentiometric Biosensors

Ultrasensitive field-effect transistor-based biosensors using quasi-two-dimensional metal oxide semiconductors were demonstrated. Quasi-two-dimensional low-dimensional metal oxide semiconductors were highly sensitive to electrical perturbations at the semiconductor–bio interface and showed competitive sensitivity compared with other nanomaterial-based biosensors. Also, the solution process made our platform simple and highly reproducible, which was favorable compared with other nanobioelectronics. A quasi-two-dimensional In₂O₃-based pH sensor showed a small detection limit of 0.0005 pH and detected the glucose concentration at femtomolar levels. Detailed electrical characterization unveiled how the device’s parameters affect the biosensor sensitivity, and lowest detectable charge was extrapolated, which was consistent with the experimental data

Low Thermal Boundary Resistance Interfaces for GaN-on-Diamond Devices

The development of GaN-on-diamond devices holds much promise for the creation of high-power density electronics. Inherent to the growth of these devices, a dielectric layer is placed between the GaN and diamond, which can contribute significantly to the overall thermal resistance of the structure. In this work, we explore the role of different interfaces in contributing to the thermal resistance of the interface of GaN/diamond layers, specifically using 5 nm layers of AlN, SiN, or no interlayer at all. Using time-domain thermoreflectance along with electron energy loss spectroscopy, we were able to determine that a SiN interfacial layer provided the lowest thermal boundary resistance (<10 m²K/GW) because of the formation of an Si–C–N layer at the interface. The AlN and no interlayer samples were observed to have TBRs greater than 20 m²K/GW as a result of a harsh growth environment that roughened the interface (enhancing phonon scattering) when the GaN was not properly protected