Two- and four-probe electrical measurements on individual tin oxide (SnO(2)) nanowires were performed to evaluate their conductivity and contact resistance. Electrical contacts between the nanowires and the microelectrodes were achieved with the help of an electron- and ion-beam-assisted direct-write nanolithography process. High contact resistance values and the nonlinear current-bias (I-V) characteristics of some of these devices observed in two-probe measurements can be explained by the existence of back-to-back Schottky barriers arising from the platinum-nanowire contacts. The nanoscale devices described herein were characterized using impedance spectroscopy, enabling the development of an equivalent circuit. The proposed methodology of nanocontacting and measurements can be easily applied to other nanowires and nanometre-sized materials.

Selectivity and low power consumption are major challenges in the development of sophisticated gas sensor devices. A sensor system is presented that unifies selective sensor‐gas interactions and energy‐harvesting properties, using defined organic‐inorganic hybrid materials. Simulations of chemical‐binding interactions and the consequent electronic surface modulation give more insight into the complex sensing mechanism of selective gas detection.

A film of gas sensitive ZnO nanoparticles has been coupled with a low-power micro light plate (µLP) to achieve a NO2-parts-per-billion conductimetric gas sensor operating at room temperature. In this µLP configuration, an InGaN-based LED (emitting at 455 nm) is integrated at a few hundred nanometers distance from the sensor material, leading to sensor photoacti-vation with well controlled, uniform and high irradiance condi-tions, and very low electrical power needs. The response curves to different NO2 concentrations as a function of the irradiance displayed a bell‐like shape. Responses of 20% to 25 ppb of NO2 were already observed at irradiances of 5 mWatts·cm-2 (applying an electrical power as low as 30 µW). In the optimum illumination conditions (around 60 mWatts · cm-2, or 200 µW of electric power), responses of 94% to 25 ppb were achieved, corresponding to a lower detection limit of 1 ppb of NO2. High-er irradiance values worsened the sensor response in all the parts-per-billion range of NO2 concentrations. The responses to other gases such as NH3, CO and CH4 were much smaller, showing a certain selectivity towards NO2. The effects of hu-midity on the sensor response are also discussed.

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties (free electron concentration $n_d$, electrical mobility $\mu$, and conductivity $\sigma$) in individual nanowires has been developed. A combined model involving thermionic emission and tunneling through interface states is proposed to describe the electrical conduction through the platinum-nanowire contacts, fabricated by focused ion beam techniques. Current-voltage $\left(I\text{−}V\right)$ plots of single nanowires measured in both two- and four-probe configurations revealed high contact resistances and rectifying characteristics. The observed electrical behavior was modeled using an equivalent circuit constituted by a resistance placed between two back-to-back Schottky barriers, arising from the metal-semiconductor-metal $\left(M\text{−}S\text{−}M\right)$ junctions. Temperature-dependent $I\text{−}V$ measurements revealed effective Schottky barrier heights up to ${\Phi }_{BE}=0.4\mathrm{eV}$.