No abstract

Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ∼200,000 cm2 V−1 s−1 is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW−1 with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz−1/2. Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization.

Zinc nitride nanowires can be synthesized by nitridation reaction of zinc powder with ammonia gas in 500ml∕min at the nitridation temperature of 600 °C for 120 min. Studies by using x-ray diffraction indicate that zinc nitride nanowires are cubic in structure with the lattice constant a=0.9788nm. Observations by using scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy show that zinc nitride is of nanowire structure. Typical room temperature photoluminescence spectrum of zinc nitride nanowires exhibits an ultraviolet emission peak at 385 nm (3.22 eV) and a blue emission band centered at 450 nm (2.76 eV).

The use of amorphous InGaZnO (IGZO) has become more and more popular especially in display technologies because of its high mobility, excellent large area uniformity, and low-temperature processability. However, unlike Si-based thin-film transistors (TFTs), the top channel surface of IGZO TFTs is extremely sensitive to air, resulting in a degraded device performance, particularly when a very-thin channel layer is used. To avoid such detrimental effects and improve the device performance, a top surface treatment such as encapsulation is necessary. In this work, very thin, 1 V IGZO TFTs with top surface modified by a self-assembled monolayer (SAM) were studied. The electrical performance of the presented TFTs was significantly enhanced after the SAM modification because of a much reduced desorption–adsorption effect on the IGZO surface. The importance of top surface condition on TFTs with ultrathin channel layers was discussed. TFTs with a 5 nm thick IGZO channel layer showed a carrier mobility almost tripled plus an 18% decrease of total trap density after the SAM treatment. The treated devices also showed a superb air stability with negligible change of electrical performance after being stored in ambient air for a year. Considering the high cost of indium, this approach has a high potential to significantly reduce the manufacturing cost of IGZO-based electronics.