Enhanced photoluminescence from ordered arrays of cadmium sulfide nanotubes synthesized using nanoscale chemical reactors.

We report enhanced room temperature photoluminescence from ordered arrays of few micrometers long cadmium sulfide nanotubes fabricated using 'nanoscale chemical reactors' of porous alumina by a unique two-chamber synthesis without using any surfactants. Photoluminescence from these nanotubes is -20 times larger than that of nanocrystalline cadmium sulfide particles prepared by bulk mixing of the same reactants. However, we rule out any quantum size effect as a source of enhanced photoluminescence from these intentionally un-passivated nanotubes. We identify sulfur deficiency in these nanotubes and directional orientation of these ordered nanotube arrays as the main reason for its superior photoluminescence as compared to agglomerated nanocrystallites of CdS prepared by bulk mixing.