Monodispersed Nanoparticle Synthesis Using Pulsed Laser Ablation and Application to Opto-electronic Devices

We report silicon (Si) nanoparticles prepared by pulsed laser ablation in constant pressure inert background gas (PLA-IBG). We demonstrate the synthesis of monodispersed, nonagglomerated Si nanocrystallites, using a novel integrated process system where a classification unit of a low-pressure-operating differential mobility analyzer (LP-DMA) was combined to the PLA-IBG unit. The LP-DMA has been designed to operate under pressures less than 5.0 Torr. We have successfully synthesized and deposited the nonagglomerated Si nanocrystallites of 3.8 nm mean diameter and 1.2 geometrical standard deviation. On the other hand, properties of indium oxide (In₂O₃) thin films prepared by pulsed laser deposition (PLD) in background gases were characterized in relation to the background gas pressures. Transparent crystalline In₂O₃ thin films could be obtained at background gas pressures above 1.0 Torr on unheated glass substrates. To develop a near-infrared-light-emitting diode with active materials of monodispersed Si nanocrystallites and with passivation layer of the In₂O₃ thin films that are highly compatible with ULSI technology. The near-infrared emission was sharp and showed a peak above the band-gap region (position: 1.17 eV, width: 0.15 eV); therefore, it presumably originates from spatial quantum confinement effects of the carriers.