Blue luminescent silicon nanocrystals prepared by ns pulsed laser ablation in water

Here the authors report on a simple and cost-effective procedure to prepare blue luminescent colloidal silicon nanocrystals (Si-ncs) in de-ionized water at room temperature and atmospheric pressure by nanosecond pulsed laser ablation. At low laser fluences well-separated and spherical Si-ncs aggregates are formed. The fluence increase leads to fragmentation of spherical aggregates and the generation of finer Si-ncs with quantum confinement size effect. After aging in de-ionized water, such irregular Si-ncs fragments get stabilized into quite regular spheres and ovals. During the aging process the increase of blue room temperature photoluminescence centered around 2.9 eV is recorded. (c) 2006 American Institute of Physics.