 |
Ernesto's Project Page - CAMP Summer 2007 |
 |
Intern: Ernesto Carrillo, Electrical Engineering
Mentor: Xihong Chen
Faculty Supervisor: Martin Moskovitz
Department: Chemistry and Biochemistry |
METAL NANOPARTICLES SEMICONDUCTOR NANOWIRES SYSTEMS
Metal-oxides were traditionally used as gas sensors. This principle is based
on the fact that the surface states which affect the electric properties of
material change under different target gases. In 1-D systems, like nanowires, the
high surface-to-volume ratio makes them natural contenders for sensors. Tin oxide
nanowires were synthesized using chemical vapor deposition (CVD) and then
transferred to a SiO2/Siwafer. Micropads of Titanium/Aluminum/Nickel/Gold
were vapor deposited which served as the source and the drain electrodes. The
electric properties of a single tin oxide nanowire device configured as a field
effect transistor were measured. It was found that oxygen decreases the
conductivity of nanowires while hydrogen does the opposite. This phenomenon
can be explained by the change of the carrier charge density in nanowires
caused by annihilation or creation of oxygen vacancies on the surface of
nanowires. Decorating the nonawires with transistor metal nanoparticles (like
Pd) is proven to enhance the sensibility of the SnO2 nanowires.
Also, supported metal particles form a Schottky junction with the semiconductor
nanowire. If the particle is small enough, catalytic processes on the surface of
the nanoparticle modulate the charge depletion region thereby modifying the
current through the nanowire. Reciprocally, the application of a gate potential
can in principle alter the surface chemistry taking place on the metal
nanoparticle. This points the way to the study of propertied (catalysis) on
single particles through the intermediacy of the charge transfer processes
involved in the reaction.
Return to the CAMP 2007 project list
