Our research focuses on both the understanding and application of heat created in nanoscale structures.
Heat is necessary for many physical, biological, and chemical processes. For example, chemical vapor deposition (CVD), which is a widely used method for material deposition, involves exposing a heated substrate to vaporized chemical precursors that react and deposit material. Typically, the entire process takes place inside an oven, but if the heat could be localized, so could the deposition.
At the nanoscale both the optical and thermal transport properties of nanostructures are much different than even the microscale. Certain metal nanoparticles have strong intereactions with visible light due to an electron resonane effect known as a plasmon resoance. At the resonant frequency, light is strongly absorbed and this energy is converted to heat in tens of nanoseconds. For nanoparticles on a substrate, the transfer of heat from the particle is reduced as the size of particle is smaller than the phonon mean-free path of the substrate. This makes it is possible to locally heat metal nanoparticles to very high tempereatures with low intensity laser.
If the nanopartlcies are in CVD. environment, material deposition can be localized. Consider an array of nanoparticles on suface, shown in the illustartion below (top to bottom). An array of noparticles is placed in a CVD environment . A focused laser heats the nanoparticles. Deposition occurs on the nanoparticles. We referr to this method as Plasmon Asssited CVD (PACVD) Shown below the schematic are SEM image of PACVD of PbO.
