Vacuum field effect transistors have been envisioned to hold the promise of replacing solid-state electronics when the ballistic transport of electrons in a nanoscale vacuum can enable significantly high switching speed and stability. However, it remains challenging to obtain high-performance and reliable field-emitter materials. In this work, we report a systematic study on the field emission of novel two-dimensional tin selenide (SnSe) with rational design of its structures and surface morphologies. SnSe in the form of atomically smooth single crystals and nanostructures (nanoflowers) is chemically synthesized and studied as field emitters with varying channel lengths from 6 μm to 100 nm. Our study shows that devices based on SnSe nanoflowers significantly improve the performance and enable field emission at a reduced voltage due to a surface-enhanced local electrostatic field, and further lead to nonlinear dependent channel scaling when the channel length is shorter than 600 nm. We measured a record-high short-channel field-enhancement factor of 50 600 for a 100 nm device. Moreover, we investigated the emission stability and measured the fluctuations of the emission current which are smaller than 5% for more than 20 hours. Our results demonstrated a high-performance and highly reliable field emitter based on 2D SnSe nanostructures and we developed an important building block for nanoscale vacuum field effect transistors.
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Effect of Tungsten Oxide Nanostructures on Sensitivity and Selectivity of Pollution Gases
We report on the different surface structures of tungsten oxides which have been synthesized using a simple post-annealing-free hot-filament CVD technique, including 0D nanoparticles (NPs), 1D nanorods (NRs), and 2D nanosheet assemblies of 3D hierarchical nanoflowers (NFs). The surface morphologies, crystalline structures, and material compositions have been characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy, respectively. The sensor performances based on the synthesized samples of various surface morphologies have been investigated, as well as the influences of operating temperature and applied bias. The sensing property depends closely on the surface morphology, and the 3D hierarchical nanoflowers-based gas sensor offers the best sensitivity and fastest response time to NH3 and CH3 gases when operated at room temperature.
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- PAR ID:
- 10202683
- Date Published:
- Journal Name:
- Sensors
- Volume:
- 20
- Issue:
- 17
- ISSN:
- 1424-8220
- Page Range / eLocation ID:
- 4801
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/s20174801
