Highly sensitive electrolyte-insulator-semiconductor (EIS) sensors were realized by the integration of Si nanowires (NWs), which were fabricated by using a simple and economic electroless wet etching technique. EIS sensors with NWs longer than 1 μm were observed to have considerably increased capacitance and high pH sensitivity. The pH sensitivity of the EIS sensor with 3.8 μm long NWs was 60.2 mV/pH, which is higher than the theoretical Nernstian of 59 mV/pH. The EIS sensors with NWs exhibited slightly worse pH hysteresis and drift properties than that of the conventional planar type EIS sensor. The increases in pH sensitivity, hysteresis and drift are attributable to the extended surface area of the EIS sensors enabled by the NWs.

Polycrystalline silicon nanowires are synthesized using a classical fabrication method commonly used in microelectronic industry: the sidewall spacer formation technique. Assets of this technological process rest on low cost lithographic tools use, classical silicon planar technology compatibility and the possibility to get by direct patterning numerous parallel nanowires with precise location on the substrate. Grounded and suspended polycrystalline silicon nanowires with a curvature radius as low as 150nm are integrated into resistors and used as gas (ammonia) sensors. Results show potential use of these nanowires for charged chemical species detection with an increase of the sensitivity with the increase of SiNWs exchange surface with the environment.

Zinc oxide (ZnO) nanowires (NW) are grown on both silicon and sapphire substrates using conventional chemical vapor deposition (CVD) system. As-grown nanostructures are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) as well as energy dispersive spectroscopy (EDS) and the results confirm high-quality c-axis growth of single-crystalline zinc oxide nanowires. Nanowire are dispersed in solvent and then placed between micro-patterned gold electrodes fabricated on silicon wafers using low cost and scalable dielectrophoresis (DEP) process for fabrication of oxygen and humidity sensors. These sensors are characterized in a vacuum chamber connected to a semiconductor analyzer. Current-voltage characteristics of each device are systematically investigated under different hydrostatic pressure of various gaseous environments such as nitrogen, argon, dry and humid air. It is observed that the electrical conductivity of the nanowires is significantly dependent on the number of oxygen and water molecules adsorbed to the surface of the metal oxide nanowire. These results are critical for development of low cost metal oxide sensors for high performance ubiquitous environmental sensors of oxygen and humidity.

The electrical characteristics of silicon nanowire (SiNW) solar cells with p-type hydrogenated amorphous silicon oxide (Eg=1.9 eV)/n-type SiNWs embedded in SiO2/n-type hydrogenated amorphous silicon (Eg=1.7 eV) structure have been investigated using a two-dimensional device simulator with taking the quantum size effects into account. The average bandgap of a SiNW embedded in SiO2 increased from 1.15 eV to 2.71 eV with decreasing the diameter from 10 nm to 1 nm due to the quantum size effect. It should be noted that under the sunlight with AM1.5G the open-circuit voltage (Voc) of SiNW solar cells also increased to 1.54 V with decreasing the diameter of the SiNWs to 1 nm. This result suggests that it is possible to enhance the Voc by the quantum size effect and a SiNW is a promising material for the all silicon tandem solar cells.

ZnO nanorods grown on plastic substrates by chemical methods are combined with both inorganic and organic p-type materials to make flexible p-n junction devices. When bent the devices generate both voltage and current peaks, which is attributed to the piezoelectric effect in the ZnO nanorods. The best device produces a maximum possible power density of 100 nWcm‑2. When vibrated at a constant frequency the voltage output by the devices scales linearly with vibration amplitude. Also, when illuminated the output of the devices drops. These effects are consistent with a piezoelectric source of the voltage.

Single wall carbon nanotubes (SWCNTs) were incorporated into lithium ion battery anodes as conductive additives in mesocarbon microbead (MCMB) composites and as a free-standing support for silicon active materials. In the traditional MCMB composite, 0.5% w/w SWCNTs were used to replace 0.5% w/w SuperP conductive additives. The composite with 0.5% SWCNTs had nearly three times the conductivity which leads to improved electrochemical performance at higher discharge rates with a 20% increase in capacity at greater than a C/2 rate. The thermal stability and safety was measured using differential scanning calorimetry (DSC), and a 35% reduction in exothermic energy released was measured using the highly thermally conductive SWCNTs as an additive. Alternatively, free-standing SWCNT papers were coated with increasing amounts of silicon using a low pressure chemical vapor deposition technique and a silane precursor. Increasing the amount of silicon deposited led to a significant increase in specific capacity (>2000 mAh/g) and coulombic efficiency (>90%). At the highest silicon loading, the surface area of the electrode was reduced by over an order of magnitude which leads to lower solid electrolyte interface formation and improved safety as measured by DSC.