Size classification of Si nanoparticles formed by pulsed laser ablation in helium background gas

Abstract.

We have developed an integrated process system for the formation of nanoparticles by pulsed laser ablation (PLA) in helium background gas, size classification using a differential mobility analyzer (DMA), and deposition on a substrate. The DMA has been improved to operate at pressures of less than 10 Torr. The classification resolution of the low-pressure operating DMA (LP-DMA), transporting properties of nanoparticles under low pressure, have been investigated theoretically in order to evaluate the performance of the size classification for the integrated system. By operating the integrated system at less than 10 Torr, we have measured the size distribution of Si nanoparticles in the gas phase formation field by sweeping the applied voltage to the LP-DMA and counting the charged nanoparticle concentration with an electrometer. Moreover, we successfully deposited the classified Si nanoparticles on a substrate by fixing the voltage. We have verified that the integrated system can be applied to the clean physical vapor deposition process for accurately size-controlled nanoparticles.