Ether-like Si–Ge hydrides for applications in synthesis of nanostructured semiconductors and dielectrics

Abstract

Hydrolysis reactions of silyl-germyl triflates are used to produce ether-like Si–Ge hydride compounds including H₃SiOSiH₃ and the previously unknown O(SiH₂GeH₃)₂. The structural, energetic and vibrational properties of the latter were investigated by experimental and quantum chemical simulation methods. A combined Raman, infrared and theoretical analysis indicated that the compound consists of an equal mixture of linear and gauche isomers in analogy to the butane-like H₃GeSiH₂SiH₂GeH₃ with an exceedingly small torsional barrier of ∼0.2 kcal mol⁻¹. This is also corroborated by thermochemistry simulations which indicate that the energy difference between the isomers is less than 1 kcal mol⁻¹. Proof-of-principle depositions of O(SiH₂GeH₃)₂ at 500 °C on Si(100) yielded nearly stoichiometric Si₂Ge₂O materials, closely reflecting the composition of the molecular core. A complete characterization of the film by RBS, XTEM, Raman and IR ellipsometry revealed the presence of Si_0.30Ge_0.70 quantum dots embedded within an amorphous matrix of Si–Ge–O suboxide, as required for the fabrication of high performance nonvolatile memory devices. The use of readily available starting materials coupled with facile purification and high yields also makes the above molecular approach an attractive synthesis route to H₃SiOSiH₃ with industrial applications in the formation of Si–O–N high-k gate materials in high-mobility SiGe based transistors.