Ether-like Si-Ge hydrides for applications in synthesis of nanostructured semiconductors and dielectrics.
Hydrolysis reactions of silyl-germyl triflates are used to produce ether-like Si-Ge hydride compounds including H(3)SiOSiH(3) and the previously unknown O(SiH(2)GeH(3))(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 H(3)GeSiH(2)SiH(2)GeH(3) with an exceedingly small torsional barrier of approximately 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(SiH(2)GeH(3))(2) at 500 degrees C on Si(100) yielded nearly stoichiometric Si(2)Ge(2)O 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(0.30)Ge(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 H(3)SiOSiH(3) with industrial applications in the formation of Si-O-N high-k gate materials in high-mobility SiGe based transistors.
Molecular structures of digermyl ether and digermyl sulphide in the gas phase, studied by electron diffraction
The structures of digermyl ether and digermyl sulphide have been determined in the gas phase by the sector microphotometer method of electron diffraction. The principal parameters for digermyl ether are: r(Ge–O)= 1·766 ± 0·004 A, r(Ge–H)= 1·531 ± 0·011 A, ∠(Ge–O–Ge)= 126·5 ± 0·4°: for digermyl sulphide, r(Ge–S)= 2·209 ± 0·004 A, r(Ge–H)= 1·512 ± 0·016 A, ∠(Ge–S–Ge)= 98·9 ± 0·3°.
Nitrogen Concentration Dependence on Boron Diffusion in Thin Silicon Oxynitrides Used for Metal‐Oxide‐Semiconductor Devices
The effect of nitrogen concentration on boron diffusion in silicon oxides (oxynitride) used for metal-oxide-semiconductor structures was investigated. The oxynitrides, which were formed by oxidizing thin, thermally grown nitrides, contained uniform amounts of nitrogen. The boron diffusion coefficients in the oxynitrides were determined, and experimental and simulated results were compared. The diffusion coefficients have an Arrhenius relationship to each concentration of nitrogen, and are smaller in higher nitrogen concentrations. A 25% concentration of nitrogen exhibited an oxynitride diffusion coefficient at least two orders smaller than that of SiO 2 . The higher the nitrogen concentration was, the larger the activation energy was. The diffusion coefficient data is useful for evaluating the boron penetration of various types of oxynitrides, including nitrided oxides. An empirical diffusion model is proposed in order to explain the experimental data qualitatively.