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We demonstrate rectifying Schottky diodes fabricated using as-grown single-walled carbon nanotubes (SWNT) ensembles, without removing the metallic SWNTs, for optoelectronic device applications. The SWNTs are contact by a low work-function metal through a high-bandgap charge-blocking layer (ZnO) resulting in highly-nonlinear current-voltage properties compared to control ensemble SWNT devices, fabricated without a charge-blocking layer, which show resistive behaviour. This significant improvement in diode behaviour is obtained by reducing source-drain leakage from the metallic SWNTs using the charge-blocking layer which channels charge transport via the semiconducting SWNTs. Moreover, we explore an alternative method of creating the charge barrier layer via oxidizing a thin film of Zn deposited on directly on the SWNTs which could potentially reduce cost and increasing scalability of this technique to obtain highly rectifying diodes from as-grown ensemble SWNTs. [ABSTRACT FROM AUTHOR]

The low quality factor (Q) of single-walled carbon nanotube (SWNT) resonators has limited their sensitivity in sensing application. To this end, we employ the technique of parametric amplification by modulating the spring constant of SWNT resonators at twice the resonant frequency and achieve 10 times Q enhancement. The highest Q obtained at room temperature is around ∼700, which is 3-4 times better than previous Q record reported for doubly clamped SWNT resonators. Furthermore, efficient parametric amplification is found to only occur in the catenary vibration regime. Our results open up the possibility to employ light-weight and high-Q carbon nanotube resonators in single molecule and atomic mass sensing. [ABSTRACT FROM AUTHOR]

Examines the ferroelectricity of perovskite-type oxides with alkylamine interlayer. Observed ferroelectric hysteresis loop in synthesized powder crystals; Element analysis.

A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical conductivity of mono- and bilayer chemical-vapor-deposited graphene. We model graphene as a truly two-dimensional (2D) material with a sheet conductivity, rather than a phenomenological effective refractive index as has been used in the literature. This technique measures both the real and imaginary part of the optical conductivity, which is important for graphene optoelectronics and metamaterials. Using this method, we obtain broadband measurements of the complex optical conductivity for mono- and bilayer graphene from ultraviolet to mid-infrared wavelengths. We also study how chemical doping with nitric acid modifies the complex optical conductivity. [ABSTRACT FROM AUTHOR]