Synthesis, properties and applications of size selected metal nanoparticle-thin film composite
structures
B.R. Mehta
Schlumberger Chair Professor
Indian Institute of Technology Delhi, India
The unprecedented research interest in the area of nanotechnology stems from the potential to
fabricate devices at nano and micro scale with improved characteristics. In this presentation, results of the
experiments carried out in our laboratory on the growth and application of size selected nanoparticles-thin
film structures will be discussed.
For realizing size dependent properties of nanoparticles, it is important that the nanoparticles are
prepared using synthesis methods which can yield controllable nanoparticle size, narrow size distribution and
uncontaminated surface structure A nanoparticle deposition facility comprising of particle synthesis system,
particle charger facility, differential mobility analyzer, in-flight sintering, nanoparticle deposition in clean
vacuum conditions along with on-line size distribution measurements has been established. The integrated
deposition set up has been used to grow metal, alloy and core-shell nanoparticles. It is important to note that
the spherical, compact and crystalline nanoparticle are grown in the gas phase and can be deposited on a
desired substrate in the final step. The nanoparticle growth system has been integrated with the thin film
deposition systems for growing nanoparticle- thin film composite structures comprising of nanoparticle
deposited on thin films and nanoparticle dispersed in the thin film matrix.
The above deposition method has been applied to grow different nanoparticle-thin film structures for
a variety of applications. Pd - rare earth metal thin film structures have been used for switchable mirror
devices with improved characteristics. By carrying out detailed study on Pd, Ag, Cu, Pd-Ag and Pd-Cu
nanoparticle and thin films, important relationship between valence band spectra and hydrogenation
properties in Pd alloys is established. Ag nanoparticle-SiO2 thin films have been used for plasmonic
applications and deposition of the thin film containing nanoparticles on Si solar cell devices show improved
photovoltaic response. Si and Si-Sn alloy nanoparticle have been dispersed in the growing SiO2 thin films
and optical and electrical characteristics of these layer have been investigated.