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The improvement of subthreshold slope due to impact ionization is compared between “standard” inversion-mode multigate silicon nanowire transistors and junctionless transistors. The length of the region over which impact ionization takes place, as well as the amplitude of the impact ionization rate are found to be larger in the junctionless devices, which reduces the drain voltage necessary to obtain a sharp subthreshold slope. [ABSTRACT FROM AUTHOR]

The electric field perpendicular to the current flow is found to be significantly lower in junctionless transistors than in regular inversion-mode or accumulation-mode field-effect transistors. Since inversion channel mobility in metal-oxide-semionductor transistors is reduced by this electric field, the low field in junctionless transistor may give them an advantage in terms of current drive for nanometer-scale complementary metal-oxide semiconductor applications. This observation still applies when quantum confinement is present. [ABSTRACT FROM AUTHOR]

• A new sensor in which ultrathin polypyrrole layer is synthesized on reduced graphene oxide (rGO) by electropolymerization. • The sensor exhibits an excellent performance for NH3 detection in the sensitivity, selectivity, response, and recovery. • The sensor operates at room temperature with good immunity to humidity. • The sensing material is based on cheap and easy-synthesis rGO. • The sensor fabrication is easy, low cost, mass production and compatible with CMOS technology. We report an ammonia (NH 3) sensor in which a ultrathin polypyrrole (PPy) layer is synthesized on reduced graphene oxide (rGO) by electropolymerization. The PPy/rGO composite is characterized by scanning electron microscopy, secondary ion mass spectrometry, Raman spectroscopy, and X-ray photoelectron spectroscopy. The sensor exhibits an excellent performance in the selective sensing of NH 3 at room temperature, having a high, fast, reversible and linear response. These performances are attributed to the synergistic effect of the ultrathin PPy layer and rGO. Specifically, NH 3 molecules are adsorbed on the ultrathin PPy layer, electrons transfer from NH 3 to the PPy layer, changing the PPy layer resistance. The ultrathin PPy layer over rGO allows NH 3 molecules to pass through and react with sp2-bonded carbon atoms, also changing the rGO resistance. Moreover, the rGO sheets are not only a support material for the ultrathin PPy electropolymerization but also provide an efficient pathway for electron transfer, thereby, accelerating the sensor response and recovery. Meanwhile, the ultrathin PPy layer plays an important role in the sensor selectivity and immunity to humidity. Our research indicates that the post-step PPy electropolymerization is very promising for sensor fabrication and compatible with CMOS technology. These make it possible to design and manufacture the PPy/rGO sensors with integrated circuits onto the same Si wafer for different applications. Importantly, the fabrication method of the present sensor is easy and low cost. Therefore it is regarded as being scalable for mass production of NH 3 sensors. [ABSTRACT FROM AUTHOR]