Synthesis of III-V semiconductors by solid-state metathesis

Solid-state precursor reactions have been investigated as a general synthetic route to binary III-V (13-15) compounds. The generic reaction scheme MX[sub 3] + Na[sub 3]Pn [yields] MPn + 3 NaX (M = Al, Ga, In; X = F, Cl, I; Pn = pnictogen = P, As, Sb) has been used to prepare crystalline powders of the III-V semiconductors. The reaction mixtures can be either heated in sealed tubes or ignited with a hot filament, and the byproduct salts are simply removed by washing with an appropriate solvent. The ignited reactions are self-propagating and highly exothermic, owing to the formation of 3 mol of sodium halide. Products from both types of reactions have been characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and solid-state NMR. In some cases, the products of the ignited solid-state metathesis (SSM) reactions differ from those of the sustained heating reactions. These differences provide clues as to reaction pathways in the solid-state precursor reactions.