Mass-limited growth in zeptoliter beakers: A general approach for the synthesis of nanocrystals

Nanoscale fabrication methods provide a unique approach to synthesize nanoscale materials. Laser-assisted embossing was used to generate close-packed arrays of hemispherical nanowells with zeptoliter (zL) volumes. The volumes of the nanowells were controlled by changing the fluence of the laser, by applying variable pressure between the mold and the substrate, and by growing an amorphous oxide on the patterned silicon. Nanowells with diameters as small as 50 nm were used as reaction vessels for the preparation of simple inorganic salts and semiconducting nanocrystals. Under most growth conditions, individual nanocrystals were formed in individual nanowells.