METALLOORGANIC ROUTES TO PHOSPHIDE SEMICONDUCTORS

Solution-phase metallo-organic routes to the semiconductors Zn3P2, Cd3P2, AlP, GaP, InP, and the ternary compounds M(II)M(IV)P2 (M(II) = Zn, Cd and M(IV) = Ge, Sn), in both bulk and nanoparticulate form, are reviewed. The syntheses fall into three classifications: (1) reactions between metallo-organics and PH3, which are termed phosphinolysis reactions; (2) alcoholysis and thermolysis reactions of silylated single-source precursors; and (3) reactions between metallo-organics and P(SiMe3)3. The reaction types are shown to have substantial mechanistic parallels, and all are elimination-condensation processes. Three stages in the elimination-condensation processes are identified: (1) the early formation of oligomers and polymers; (2) the later formation of semiconductor nanoparticles; and (3) the formation of bulk-like materials in the limit. The conditions required to form nanoparticles are close to those required for the formation of bulk semiconductors. Factors that likely influence the elimination-condensation stages achieved in solution are analysed. Although the scope of the review is limited to phosphide semiconductors, the conclusions reached are likely valid for all solution-phase metallo-organic syntheses of semiconductor compounds.