SYNTHESIS OF III-V SEMICONDUCTORS BY SOLID-STATE METATHESIS

Solid-state precursor reactions have been investigated as a general sy nthetic route to binary III-V (13-15) compounds. The generic reaction scheme MX3 + Na3Pn --> MPn + 3 NaX (M = Al, Ga, In; X = F, Cl, I; Pn = pnictogen = P, As, Sb) has been used to prepare crystalline powders o f the III-V semiconductors. The reaction mixtures can be either heated in sealed tubes or ignited with a hot filament, and the byproduct sal ts are simply removed by washing with an appropriate solvent. The igni ted reactions are self-propagating and highly exothermic, owing to the formation of 3 mol of sodium halide. Products from both types of reac tions have been characterized by powder X-ray diffraction, scanning el ectron microscopy, energy dispersive spectroscopy, and solid-state NMR . In some cases, the products of the ignited solid-state metathesis (S SM) reactions differ from those of the sustained heating reactions. Th ese differences provide clues as to reaction pathways in the solid-sta te precursor reactions.