Synthesis of Silicon Nanocrystals with Erbium-Rich Surface Layers

Abstract

A route to silicon nanocrystals with erbium-rich surface layers is described involving the initial pyrolysis of disilane to produce nucleation and growth of the Si core followed by a second thermal annealing step in the presence of the volatile complex Er(tmhd)3 (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionato). These nanoparticles were structurally characterized by transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray analysis, and extended X-ray absorption fine structure methods, while spectroscopic characterization was achieved via photoluminescence and UV−visible absorption spectroscopies. The effects of altering the length of the pyrolysis oven and its temperature, the disilane flow rate, and the Er(tmhd)3/helium carrier gas flow rate on the mean nanoparticle feature size are noted. Interestingly, the characteristic Er3+ near-infrared photoluminescence at 1540 nm is not detected in the as-formed nanoparticles but can be observed after a brief vacuum anneal at 800 °C.