The electric field emission behavior of vertically aligned few-layer graphene was studied in a parallel plate–type setup. Few-layer graphene was synthesized in the absence of any metallic catalyst by microwave plasma enhanced chemical vapor deposition with gas mixtures of methane and hydrogen. The deposit consists of nanostructures that are several micrometers wide, highly crystalline stacks of four to six atomic layers of graphene, aligned vertically to the substrate surface in a high density network. The few-layer graphene is found to be a good field emitter, characterized by turn-on fields as low as 1 V/μm and field amplification factors up to several thousands. We observe a clear dependence of the few-layer graphene field emission behavior on the synthesis parameters: Hydrogen is identified as an efficient etchant to improve field emission, and samples grown on titanium show lower turn-on field values and higher amplification factors when compared to samples grown on silicon.

Carbon nanotube field-effect transistors (CNT FETs) have many possible applications in future nanoelectronics due to their excellent properties. However, one of the major challenges regarding their performance is the noticeable gate hysteresis which is often displayed in their transfer characteristics. The hysteresis phenomenon is often attributed to water-mediated charge transfer between the CNT and the dielectric layer or the CNT and the water layer itself. In this study, we implement the usage of current versus time measurements in addition to the traditional transfer characteristics to accurately extract the time constants of the hysteresis of suspended and on-surface CNT FETs. Following a thorough study, we provide experimental evidence that the hysteresis phenomenon of suspended CNT FETs, as well as of on-surface CNT FETs which operate at low gate voltage regimes (|V g | < 3 V), is based on gate-induced, water-assisted redistribution of mobile charge on the SiO 2 surface, and is not related to charge injection from the CNT itself. Our model is confirmed by an electronic-force-microscopy-based measurement technique which enables us to quantify the temporal surface charge distribution while measuring CNT currents.

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The static and dynamic properties of magnetization have been investigated for polymer-coated magnetite nanoparticles with sizes from 5 to 15 nm. The analysis of the temperature dependence of zero-field-cooled magnetization indicates that the effective anisotropy constant is found to increase with the decrease of particle size, which is ascribed to the increase of surface anisotropy. The relaxation of the remanent magnetization clearly shows the signature of dominant dipolar interparticle interaction. The dynamics of magnetization also indicates the signature of glassy magnetic behaviour. The memory effect in the temperature dependence of field-cooled magnetization is noticed, which is inconsistent with the glassy magnetic behaviour.