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Abstract Internal photoemission of electrons from uncapped monolayer graphene to insulating SiO 2 has been observed in samples prepared by water-intercalation based graphene transfer. The barrier height between the graphene Fermi level and the oxide conduction band bottom was reproducibly found to be 4.1–4.2 eV. Moreover, this value was weakly sensitive to the contacting metal work function (Al, Cu, Au). This barrier height corresponds to an effective work function of graphene close to 5.0 eV, which is nearly 0.5 eV higher than the usually reported vacuum value. Highlights • Internal photoemission of electrons has been detected from uncapped monolayer graphene. • Effective work function (EWF) of graphene has been determined to be 5.0 eV. • EWF of graphene at the interface with SiO 2 is 0.5 eV higher than the vacuum value. [ABSTRACT FROM AUTHOR]

In the recent decade, there is a growing interest in Hf 0.5 Zr 0.5 O 2 (HZO) thin films owing to their well-behaved ferroelectricity and high compatibility with semiconductor integrated circuit technology. The ferroelectric properties of HZO are highly pertinent to the wake-up effect, which has been reported to be associated with the monoclinic (m-), orthorhombic (o-), and tetragonal (t-) phases. However, it is very challenging to distinguish the o- and t- phases by conventional X-ray diffraction. In this study, the HZO thin films with and without the need for the wake-up process to enhance the ferroelectricity were prepared, and the precession electron diffraction (PED) phase mapping technique was utilized to identify the crystalline phases in the HZO layers. The PED characterization reveals the correlation between the phase transformation and the wake-up effect in HZO. The absence of the t-phase is responsible for the wake-up-free property in the ferroelectric HZO thin film. The wake-up-free and pronounced ferroelectricity of the nanoscale HZO thin film in this study may bring a practical impact on a variety of ferroelectric applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Crystalline vanadium dioxide (VO2) thin films were prepared by annealing amorphous VO2 films which were deposited by atomic layer deposition on a SiO2 substrate. A large influence of the oxygen partial pressure in the annealing ambient was observed by means of in-situ X-ray diffraction. In the range between 1 and 10Pa of oxygen the interesting VO2(R) phase crystallized near 450°C. Between 2 and 10Pa of oxygen, metastable VO2(B) was observed as an intermediate crystalline phase before it transformed to VO2(R). Anneals in inert gas did not show any crystallization, while oxygen partial pressures above 10Pa resulted in oxidation into the higher oxide phase V6O13. Film thickness did not have much effect on the crystallization behavior, but thinner films suffered more from agglomeration during the high-temperature crystallization on the SiO2 substrate. Nevertheless, continuous polycrystalline VO2(R) films were obtained with thicknesses down to 11nm. In the case where VO2(R) was formed, the semiconductor–metal transition was observed by three complementary techniques. This transition near 68°C was characterized by X-ray diffraction, showing the transformation of the crystal structure, by spectroscopic ellipsometry, mapping optical changes, and by sheet resistance measurements, showing resistance changes larger than 2 orders of magnitude between the low-temperature semiconducting state and the high-temperature metallic state. [ABSTRACT FROM AUTHOR]

Abstract: We report the large area growth of highly conductive carbon nanosheets (CNS) composed of few layer graphene on 200mm diameter Si substrates using conventional radio frequency plasma-enhanced chemical vapour deposition. Raman spectroscopy is used to characterise the evolution of the CNS nucleation and growth with time in conjunction with TEM revealing the nano-sized graphene-like nature of these films and the intimate contact to the substrate. An individual sheet can have edges as thin as 3 graphene layers. The influence of the growth support layer is also discussed as film growth is compared on titanium nitride (TiN) and directly on Si. Electrochemical cyclic voltammogram (CV) measurements reveal these layers to form an excellent electrical contact to the underlying substrate with excellent stability towards oxidation whilst having a large electrochemical surface area. The resistance of a 150nm film was measured to be as low as 20μohmcm. The high percentage of narrow few layer graphene edge sites exposed allows for faster electrochemical reaction rates compared to carbon nanotubes (CNTs) and other electrode materials (glassy carbon and Pt). [Copyright &y& Elsevier]

• Dual gated WS 2 MOSCAP devices were fabricated to measure both n/p-branch C-V response. • Frequency/temperature dependent CV curves were correlated with WS 2 MOSCAP simulation. • Interface trap density across the bandgap (D IT (E)) is extracted for 2ML WS 2. Dual gated 2ML WS 2 MOS Capacitors have been fabricated with capacitance values as high as 2.7uF/cm2 (with single sheet charge centroid assumption for the WS 2 channel). Frequency and temperature dependent C-V measurements were correlated with simulations to extract the interface trap density-energy (D IT (E)) profile. We observe an exponentially decaying defect distribution from the conduction band (E C) edge with a magnitude of 8 × 1013 cm−2 eV−1 and an inverse slope of 0.12 eV and a similar distribution with a peak magnitude of 1.2 × 1014 cm−2 eV−1 from the valence band (E V) edge with an inverse slope of 0.12 eV. [ABSTRACT FROM AUTHOR]