Facile routes of manufacturing silicon quantum dots on a silicon wafer and their surface activation by esters of N-hydroxysuccinimide

Fluorescent silicon quantum dots (SiQDs) could be prepared by reduction of hydrogen silsesquioxane, etching of silicon powers with wetting chemistry techniques or electrolysis of a wafer catalyzed by polyoxometalates. Chemical modifications are indispensable for the stability of the SiQDs photoluminescence and wider applications of SiQDs. Facile routes of manufacturing SiQDs derived from a silicon wafer and its surface functionalization by N-hydroxysuccinimide (NHS) esters were described in this work in detail. Firstly, the porous silicon chip was prepared by nanosilver-assisted electroless chemical etching. Then the chip was etched successively with hydrofluoric acid/nitric acid solutions until it emitted dazzling red fluorescence which claimed the achieved SiQDs on silicon substrates (SiQDs/Si). Finally, surface NHS esters were fabricated on such an SiQDs/Si chipthrough stepwise modifications, which were tested by the amidation between the NHS esters and n-octylamine. The fluorescence emission of the SiQDs/Si chip almost remained unchanged during the successively chemical modifications, which indicated the SiQDs had capabilities of enduring the sustained high temperature and organic media. Meanwhile, the SiQDs did not leave from the silicon substrate during the surface tuning. The SiQDs obtained by ultrasonication of an SiQDs/Si chip in water were investigated by transmission electron and atomic force microscopies.