The gas-phase reaction products of silacyclobutane (SCB) and 1, 1-dideuterio-silacyclobutane (SCB-d(2)) from a hot-wire chemical vapor deposition (HWCVD) chamber were diagnosed in situ using vacuum ultraviolet (VUV) laser single-photon ionization (SPI) coupled with time-of-flight (TOF) mass spectrometry. The SCB molecule was found to decompose at a filament temperature as low as 900 degrees C. Both Si- (silylene, methylsilylene, and silene) and C-containing (ethene and propene) species were produced from the SCB decomposition on the filament. Ethene and propene were detected by the mass spectrometer. It is demonstrated that the formation of ethene is favored over that of propene. The experimental study of hot-wire decomposition of SCB-d(2) shows that propene is most likely produced by a process that is initiated by a 1,2-H(D) migration to form n-propylsilylene, followed by an equilibration with silacyclopropane, which then decomposes to propene. The detection of ethene in our experiment indicates that a competitive route of fragmentation exists for SCB decomposition on the filament. It has been shown that this competitive route occurs without H/D scrambling. The highly reactive silylene, silene, and methylsilylene species produced from SCB decomposition underwent either insertion reactions into the Si-H bonds of the parent molecule or pi-type addition reaction across the double and triple CC bonds. The dimerization product of silene, 1,3-disilacyclobutane, at m/z = 88 was also observed.

Non-polar (Zn, Mg)O/ZnO quantum wells (QWs) have been grown on a r-plane sapphire by molecular beam epitaxy. The heterostructures are fully oriented and show a single wurtzite phase at least up to 40% Mg content, as evidenced by means of the x-ray pole figures analysis. The microstructure is dominated by stacking faults and related partial dislocations as shown by the transmission electron microscopy analysis. A series of QWs with different widths has then been studied, showing the absence of the quantum confined Stark effect. The photoluminescence energies of the QWs are satisfactorily simulated when taking into account the variation of the exciton binding energy with the QW width. Different approaches for the calculation of the QW exciton ground state energies are proposed and compared.

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