Efficient and Dense Electron Emission from a SiO Tunneling Diode with Low Poisoning Sensitivity.

We report a tunneling diode enabling efficient and dense electron emission from SiO with low poisoning sensitivity. Benefiting from the shallow SiO channel exposed to vacuum and the low electron affinity of SiO (0.9 eV), hot electrons tunneling into the SiO channel from the cathode of the diode are efficiently emitted into vacuum with much less restriction in both space and energy than those in previous tunneling electron sources.

Interlayer electrical resistivity of rotated graphene layers studied by in-situ scanning electron microscopy.

Interlayer electrical transport between two-dimensional atomic crystals can be strongly modulated by the rotational misalignment between them. However, the experimental study on the interlayer electrical transport between rotated two-dimensional atomic crystals with variable rotation angles is challenging. Here, an in-situ scanning electron microscopy method is developed to study the interlayer electrical transport between rotated graphene layers.

Single-walled carbon nanotube thermionic electron emitters with dense, efficient and reproducible electron emission.

Thermionic electron emitters have recently been scaled down to the microscale using microfabrication technologies and graphene as the filament. While possessing several advantages over field emitters, graphene-based thermionic micro-emitters still exhibit low emission current density and efficiency. Here, we report nanoscale thermionic electron emitters (NTEEs) fabricated using microfabrication technologies and single-walled carbon nanotubes (SWCNTs), the thinnest conducting filament we can use.

Influence of water vapor on the electronic property of MoS field effect transistors.

The influence of water vapor on the electronic property of MoS field effect transistors (FETs) is studied through controlled experiments. We fabricate supported and suspended FETs on the same piece of MoS to figure out the role of SiO substrate on the water sensing property of MoS. The two kinds of devices show similar response to water vapor and to different treatments, such as pumping in the vacuum, annealing at 500 K and current annealing, indicating the substrate does not play an important role in the MoS water sensor.

Asymmetric Light Excitation for Photodetectors Based on Nanoscale Semiconductors.

A photodetector is a key device to extend the cognition fields of mankind and to enrich information transfer. With the advent of emerging nanomaterials and nanophotonic techniques, new explorations and designs for photodetection have been constantly put forward. Here, we report the asymmetric-light-excitation photoelectric detectors with symmetric electrical contacts working at zero external bias.

Whole-journey nanomaterial research in an electron microscope: from material synthesis, composition characterization, property measurements to device construction and tests.

The whole-journey nanomaterial research from material synthesis, composition and structure characterizations, property measurements to device construction and tests in one equipment chamber provides a quick and unambiguous way of establishing the relationships between synthesis conditions, composition and structures, physical properties and nanodevice performances of nanomaterials; however, it still proves challenging. Herein, we report the whole-journey research of tungsten oxide nanowires in an environmental scanning electron microscope (ESEM) equipped with an x-ray energy dispersive spectrometer (EDS) and a multifunctional nanoprobe system. Tungsten oxide nanowires are synthesized by irradiating a tungsten filament using a high-energy laser in O atmosphere with the dynamic growth processes of nanowires being directly visualized under ESEM observation.

Microcavity-Integrated Carbon Nanotube Photodetectors.

Carbon nanotubes (CNTs) are considered to be highly promising nanomaterials for multiwavelength, room-temperature infrared detection applications. Here, we demonstrate a single-tube diode photodetector monolithically integrated with a Fabry-Pérot microcavity. A ∼6-fold enhanced optical absorption can be achieved, because of the confined effect of the designed optical mode.

Tunable graphene micro-emitters with fast temporal response and controllable electron emission.

Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament.

Remarkable influence of slack on the vibration of a single-walled carbon nanotube resonator.

We for the first time quantitatively investigate experimentally the remarkable influence of slack on the vibration of a single-walled carbon nanotube (SWCNT) resonator with a changeable channel length fabricated in situ inside a scanning electron microscope, compare the experimental results with the theoretical predictions calculated from the measured geometric and mechanical parameters of the same SWCNT, and find the following novel points. We demonstrate experimentally that as the slack s is increased from about zero to 1.8%, the detected vibration transforms from single-mode to multimode vibration, and the gate-tuning ability gradually attenuates for all the vibration modes.

The intrinsic origin of hysteresis in MoS2 field effect transistors.

We investigate the hysteresis and gate voltage stress effect in MoS2 field effect transistors (FETs). We observe that both the suspended and the SiO2-supported FETs have large hysteresis in their transfer curves under vacuum which cannot be attributed to the traps at the interface between the MoS2 and the SiO2 or in the SiO2 substrate or the gas adsorption/desorption effect. Our findings indicate that the hysteresis we observe comes from the MoS2 itself, revealing an intrinsic origin of the hysteresis besides some extrinsic factors.