Hydrogen-terminated diamond field-effect transistor with AlOx dielectric layer formed by autoxidation

Large-Area Flexible Printed Thin-Film Transistors with Semiconducting Single-Walled Carbon Nanotubes for NO2 Sensors

Development of large-area, low-cost, low-voltage, low-power consumption, flexible high-performance printed carbon nanotube thin-film transistors (TFTs) is helpful to promote their future applications in sensors and biosensors, wearable electronics, and the Internet of things. In this work, low-voltage, flexible printed carbon nanotube TFTs with a large-area and low-cost fabrication process were successfully constructed using ultrathin (∼3.6 nm) AlO_x thin films formed by plasma oxidation of aluminum as dielectrics and screen-printed silver electrodes as contact electrodes. The as-prepared bottom-gate/bottom-contact carbon nanotube TFTs exhibit a low leakage current (∼10^-10 A), a high charge carrier mobility (up to 9.9 cm² V^-1 s^-1), high on/off ratios (higher than 10⁵), and small subthreshold swings (80-120 mV/dec) at low operation voltages (from -1.5 to 1 V). At the same time, printed carbon nanotube TFTs showed a high response (ΔR/R = 99.6%) to NO₂ gas even at 16 ppm with a faster response and recovery speed (∼8 s, exposure to 0.5 ppm NO₂), a lower detection limit (0.069 ppm NO₂), and a low power consumption (0.86 μW, exposure to 16 ppm NO₂) at a gate voltage of 0.2 V at room temperature. Moreover, the printed carbon nanotube devices exhibited excellent mechanical flexibility and bias stress stability after 12,000 bending cycles at a radius of 5 mm and a bias stress test for 7200 s at a gate voltage of ±1 V, which originated from the ultrathin and compact AlO_x dielectric and the super adhesion force between screen-printed silver electrodes and polyethylene terephthalate substrates.

Ohmic Contact of Pt/Au on Hydrogen-Terminated Single Crystal Diamond

In this study, contact properties of platinum/gold (Pt/Au) on the surface of hydrogen-terminated single crystal diamond (H-SCD) were studied with several treatment conditions. The electrodes of Pt (20 nm)/Au (100 nm) were deposited on H-SCD surface by electron beam evaporation technique. Then, the specific contact resistance (ρc) of the as-fabricated sample was measured by the circular transmission line model, which showed good ohmic properties with the value of 5.65 × 10−4 Ω·cm2. To identify the thermal stability of Pt/Au/H-SCD, the sample was annealed in hydrogen ambient from 200 to 700 °C for 20 min at each temperature. As the temperature increased, ρc demonstrated better thermal stability. In addition, the barrier height was evaluated to be −0.67 ± 0.12 eV by X-ray photoelectron spectroscopy (XPS) technique.