Built-in charges and photoluminescence stability of 3D surface-engineered silicon nanocrystals by a nanosecond laser and a direct current microplasma

Herein we report on three-dimensional (3D) surface engineering of silicon nanocrystals (Si-ncs) at the nanoscale by a combined nanosecond laser (ns-L) and atmospheric-pressure direct-current microplasma process which have allowed tailoring surface chemistries as well as surface charges. We demonstrate that ns-L and microplasma processing in ethanol can be efficiently used to form built-in charges and stabilize optoelectronic properties of Si-ncs with quantum confinement effects. These processing techniques are therefore capable of producing Si-ncs with varying surface chemical composition that allow easy dispersion in liquid, enhanced stability, and photoluminescence properties including the possibility of changing the polarity of the surface charges. Furthermore, we have been able to observe that the combined effect of ns-L and microplasma processing can lead to unusual formation of built-in charges within the subsurface layers which may present interesting opportunities for carrier dissociation/transport. Finally, we have studied the conduction properties of Si-ncs self-organized assemblies that resulted from surface engineered Si-ncs.