Synthesis and characterization of Na-containing amorphous and nanocrystalline Si from the reaction of NaSi with AlCl3

Abstract

Amorphous silicon (a-Si) and nanocrystalline silicon (nc-Si) have been prepared through a new solid-state reaction route using NaSi and AlCl3. a-Si was obtained by heating the mixed precursors at 90°C in a sealed Pyrex tube. nc-Si was prepared by annealing the a-Si at 600°C under vacuum for 2h. 23Na MAS NMR signal of the a-Si appears at a chemical shift different from those of silicon clathrates and NaSi, which indicates the presence of sodium in the structure of a-Si. 23Na MAS NMR spectroscopy indicates less Na element is contained in the lattice of nc-Si.